A Window in Time: The Effect of Temporal Reconsolidation …€¦ · · 2018-04-10Word count:...

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Temporal Reconsolidation of Appetitive Behaviour

A Window in Time: The Effect of Temporal Reconsolidation Boundaries on the Persistence of Appetitive Behaviour

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Candidate number: 11510

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Abstract

There is ample evidence that the loss of operant behaviour seen in extinction does not reflect

a loss of memory or even behaviour (Bouton 1984, 1988, 2002; Bouton & Bolles, 1979;

Acosta, Boynton, Kirschner & Neisewander, 2005). However, reconsolidation provides a

means of updating the original conditioning memory, altering the pervasiveness of previously

reward-paired cues (Nader, 2003). Previous research has implicated context in incentive

motivation for appetitive behaviours (Crombag & Shaham, 2002). We used the

extinction/reinstatement model to examine the effects of reconsolidation on reinstatement of

extinguished sucrose-seeking behaviour in 32 mice. Animals were trained to self-administer

sucrose and subsequently underwent extinction. The conditioning memory was then

reactivated either 30 minutes or 6 hours before they were tested twice for cue and context-

primed reinstatement of the extinguished appetitive behaviour. The results of the study

indicated the renewal of behaviour as a function of context but reconsolidation was not

shown. The potential explanations for this, such as boundary conditions, are explored.

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Nomenclature:

NCSPP: non-conditioned stimuli period; CSPP: conditioned stimulus presentation period;

CS: conditioned stimulus; US: unconditioned stimulus; RET30min: conditioned group

reactivated thirty minutes before test; RET6hr: conditioned group reactivated six hours before

test.

Acknowledgements:

With particular thanks to Dr. Hans Crombag; firstly, for his initial suggestion of this subject

as an area for experimentation and secondly, for his continued help and support throughout

this project‟s completion.. I would like to thank the support technicians in the animal research

facility at University of Sussex for their help and David Mawer for supervising us within that

facility. Finally, I would like to thank Thomas Ridley-Siegert, with whom I jointly collected

the data for this project, for being a superb dissertation partner.

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A Window in Time: The Effect of Temporal Reconsolidation Boundaries on the Persistence of Appetitive Behaviour.

Consolidation is a time-dependent stabilization process through which short-term memories

(STM) are converted into persistent or long-term memories (LTM) (McGaugh, 1966, 2000;

Glickman, 1961). There is evidence to suggest that, once consolidated, memories cannot be

disrupted using amnestic agents such as protein-synthesis inhibitors or hypoxia (Dudai,

2004). However, consolidated memory traces can be altered when reactivation returns them

to a transient state (Nader, 2003; Sara, 2000; Gordon & Spear, 1973). This instigates memory

processes similar to those seen in new learning: the memory is briefly labile before being

merged back into the long term memory (LTM); this phenomenon is called “reconsolidation”

(Nader & Hardt, 2009). This brief period when the memory is mutable means that

reconsolidation can disrupt the initial memory trace, permanently altering it (Nader, 2003).

Reconsolidation research has been conducted in several classes of animals including

Insecta (honeybees: Eisenhardt, Menzel, & Stollhoff, 2008), Nematodes (round worms: Rose

and Rankin, 2006) Malacotraca (crabs: Pedreira, Pérez-Cuest, & Maldonado, 2002), and

Mammalia (rats: Nader et al, 2000) (mice: Chevere, et al., 2002) (humans: Gomez, Hardt,

Hupbach & Nadel, 2007). The fact that reconsolidation has been illustrated in an array of

species suggests that it is vitally important for updating learnt behaviours and memories.

Reconsolidation may do this by integrating common elements from related memories,

thereupon, reducing cognitive load (Walker, Brakefield, Hobson, & Stickgold, 2003).

A number of studies have used instrumental fear conditioning to study reconsolidation

of associative memories (Dębiec, Doyére, Nader & LeDoux, 2005; Schiller, Levy, Niv,

LeDoux & Phelps, 2008; Monfils, Cowansage, Klann & LeDoux, 2009). In this model, a

conditional stimulus (CS, for example, a tone) is paired with a negative unconditional

stimulus (US, for example, foot shock), producing a behaviour (for example, freezing). This

research has demonstrated that immediate (but not delayed) extinction, after the

commencement of reconsolidation, leads to attrition of responding (Schiller et al. 2008;

Monfils et al., 2009).

Research focussing on the extinction of operant appetitive learning, when the CS is

coupled with a rewarding US (for example, drugs) when an animal performs a behaviour (for

example pressing a lever), is limited. As with fear conditioning, learned responses can be

extinguished by presenting the uncoupled CS repeatedly (Bouton & Swartzentruber, 1991;

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Bouton, 2002; Bouton & Moody, 2004). A number of factors (for example context) can

reinstate responding (Bouton, 1984, 1988; Bouton & Bolles, 1979; Acosta et al., 2005). One

suggested reason for this is that testing often occurs shortly after extinction making the

extinction memory more retrievable than the acquisition memory; as the time between

extinction and testing increases the extinction memory becomes harder to retrieve, inducing

spontaneous recovery (Bouton, 1993). This suggests that extinction does not destroy the

acquisition memory but instead is “new learning” which is stored along with the initial

association. This extinction memory inhibits the expression of the conditioning memory

(Pavlov, 1927) and the instrumental action achieves an additional “meaning”; rendering the

signal‟s significance context specific.

As the initial conditioned behaviour reappears in a new context it has been proposed

that conditioning associations are temporally more stable than extinction associations

(Bouton & Bolles, 1979; Bouton, 1993). Bouton (2002) advances that the reason for this that

extinction is the second thing learnt about the CS. In order for extinction to overshadow

conditioning associations, it would have to occur repeatedly, in a number of different

contexts consequently encouraging the pervasiveness of the association (Bouton, 2006).

Ideally, such “new learning” would need to be ubiquitous to all new contexts (Bouton, 2002).

However, the initial memory trace would remain, thus, it is imperative to make the distinction

between the absence of behaviour and the absence of memory (Abel & Lattel, 2004). The

most effective means of altering behaviour is to modify the initial memory rather than

produce a second association.

Stollhoff et al. (2008) argue that for extinction to become the dominant association the

original conditioning memory must be updated using reconsolidation. This would mean that

extinction would supplant, rather than replace, the original memory (Quirk et al., 2000;

Akirav, Maroun & Raizel, 2006).

Research into reconsolidation is important for a number of reasons. Firstly, anxiety

disorders, for example phobias, could be treated by altering the initial memory (Bernstein &

Victor, 2009; Weisberg, 2009). An estimated lifetime prevalence of anxiety disorders is 18%

(Alonso et al., 2004; Chiu, Demler, Kessler, Merikangas & Walters, 2005) producing a huge

burden on the economy and healthcare systems. Exposure based therapies for anxiety

disorders operate on the principle of extinction and, therefore, it seems logical that relapse is

reinstatement of the conditioning association in a new context (Bruce et al., 2005; Bouton,

Gutiérrez, Moody & Zilski 2006). Therefore, a treatment which alters the original fear

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association would be invaluable as a behavioural therapy (Schiller, 2010). To this end,

research into reconsolidation of fear conditioning has already been carried out with some

success (Monfils et al., 2009; Nader, 2003).

Moreover, reconsolidation research would be of inestimable value for drug addiction

treatment. Drug addiction is defined as a progressive, compulsive disorder characterized by

recurrent craving and relapse even after long periods of abstinence (Olausson, Quinn Taylor

& Torregrossa, 2009).

According to Gordon, Godfrey, Parrott & Tinsley (2006) the annual economic and

social costs of drugs is approximately £15.4 billion in the UK. Drugs with high abuse

potentials, such as heroin and crack cocaine, also put huge strain on the NHS. There are

approximately 320,000 heroin and/or crack cocaine users in England (National Treatment

Agency Media Release 2009) an estimated 48% of which seek treatment each year

(Department of Health and the National Treatment Agency 2010). However, relapse rates are

high; 40-60% of addicts treated resume drug abuse within a year (McLellan & McKay,

1998). This suggests that the extinction method of drug-related cues in rehabilitation clinics is

ineffective (Conklin & Tiffany, 2002).

A possible reason for this high lapse rate is that associations acquired in the

rehabilitation centres are not applicable post-discharge. In animal models, reward associated

cues can reinstate responding (Bouton, 1984, 2002; Rescorla, 2001; Acosta et al., 2005;

Olausson et al., 2009; Crombag et al., 2002b). Stewart, de Wit, & Eikelboom (1984)

suggested a similar mechanism occurs in humans and that drug paired stimuli acquire

reinforcing and motivational effects. Neuroimaging studies have shown that drug related cues

activate the same meso-cortico-limbic circuitry as drugs (Contoreggi et al., 1996; Volkow et

al., 2006). Context has a marked effect on both extinction and reinstatement of conditioned

behaviour (Denniston, Gunther & Miller, 1998); as both discrete conditioned stimuli (for

example tone) and discriminative stimuli (for example smells) can be used by laboratory

animals as indicators of reward availability (Ettenberg &McFarland 1997; Dankiewicz,

Gracy, Koob & Weiss, 2000; Aicardi, Burattini, Janak & Zironi, 2006). When returned to

their drug conditioned context post-extinction these cues can reinstate drug seeking behaviour

(Crombag & Shaham, 2002a; Crombag, Grimm, & Shaham, 2002b; Bossert, Gray, Lu, &

Shaham, 2006; Bouton & Ricker, 1994). This is direct evidence that the context in which an

association is learnt is key to expressions of maladaptive behaviour (Robinson & Yager,

2010).

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Although extinction is highly context specific (Bouton, 2002), reconsolidation

directly alters the salience of the initial association (Nader, 2003). Dudai (2004) describes

reconsolidation as an update system wherein new information revises the initial memory

using “synaptic consolidation” stabilizing memories in a matter of hours (Dudai & Morris,

2000). This revision occurs through two major mechanisms: training induced updating and

updating instigated by dissonance between the training and reactivation memories (Morris &

Wang, 2010). Consequently, reconsolidation could allow for the salience of drug related

stimuli to become diminished across multiple dimensions.

In the past, research into reconsolidation has used a number of paradigms to disrupt

the reactivated memory. These include electric shock (Lewis, Miller & Misanin, 1968),

hypoxia (Sara, 1973), hypothermia (Mactutus, Smith & Riccio, 1980) and protein synthesis

inhibitors (Anokhin, Tiunova, Rose, 2002). These studies have shown the brief window in

which reconsolidation occurs is immediately following reactivation. For example, the protein

synthesis inhibitor anisomycin (ANI) has been shown to produce amnestic effects when

administered anywhere between thirty minutes before to six hours post-training (Mark &

Watts, 1971; Bjorklund et al., 1986; Freeman, Rose & Scholey, 1995; Debiec, LeDoux, &

Nader, 2002). Such treatments have been shown to stop working after six hours indicating

that reconsolidation occurs within a six hour window (Schafe & Ledoux, 2000). The temporal

sensitivity of reconsolidation has also been shown to effect the reactivation period, which

must be kept brief (under ten minutes) in order to stop extinction (Frankland et al., 2004). A

recent study by Monfils et al. (2009) exploited the transient reconsolidation window in a fear

conditioning study. Their reason for this is that the amnestic treatments that are currently in

use are not viable for therapeutic treatment. Instead, this paradigm involved a single ten

minute retrieval session prior to testing and results showed enhanced extinction.

Since Monfils et al. (2009) study there has yet to be an appetitive study examining the

effect of context on reconsolidation using temporal reconsolidation. Like most abused drugs,

palatable food releases dopamine into the nucleus accumbens-shell (Avena, Hoebel & Rada,

2005) suggesting a neurochemical similarity between intermittent sucrose and drug bingeing.

Furthermore, food cues acquire incentive motivational properties in a similar way to abused

drugs (Robinson & Yager, 2010) supporting the assertion that research using natural rewards

can further our understanding of abused drugs (Kelley & Berridge, 2002). If reconsolidation

can be effectively achieved, then this paradigm could be used therapeutically to reduce

maladaptive behaviours. We hypothesis that appetitive behaviour will be subject to renewal

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in animals tested six hours after memory reactivation. Conversely, animals tested thirty

minutes after reactivation will show diminished appetitive behaviours.

Method

Subjects:

The subjects were 32 C57BL mice housed in plastic and stainless steel cages in a

climate controlled facility (temperature: mean= 21.7⁰C, max= 22.6⁰C, min= 21.2⁰C. Relative

Humidity: mean= 47, max= 57, min= 46) in groups of 4 littermates. Mice had an initial mean

weight of 21.4 grams and maintained on a 24 hour circadian cycle. The animals were food

deprived throughout the study and maintained at 90% of their initial body weight. Water was

ad libitum for the duration of the experiment. The procedures were conducted in accordance

with the UK 1986 Animals (Scientific Procedures) Act 9 (project licence PPL 707072).

Apparatus:

The experiment was conducted in two sets of operant chambers. The following was

the same in for each context: Skinner boxes, measuring 27 x 25.8 x 30.4 cm in length, width,

and height respectively, were constructed from two metal and two clear acrylic walls. The

active lever (5.28cm²) was located (4cm) to the left of the sucrose receptacle

(counterbalanced to the right for half of the mice). The receptacle (width= 1.8cm, height=

2.3cm, depth= 2.9cm) contained an infra-red beam that recorded head-entries. The 10%

sucrose (approx. 50µl) was coloured with 10 drops (per 500ml) of “silver spoon” green food

colouring and by 5ml plastic syringes and a compressed-air pump.

A computer running (MET-PC-IV) was interfaced with the chambers and recorded

lever presses (active and inactive), head entries into the receptacle and the times at which the

behaviours occurred.

Operant chambers were located in wooden cabinets on one side of the experimental

room. The average background noise varied within each cabinet; the CS tone was set at 10db

above the background noise for each chamber. The CS was delivered by a speaker, mounted

on the cabinet roof, above the chamber.

All equipment was washed with fragrance-free soap and water between sessions and

wiped with 70% ethanol between days.

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The boxes from context A and B differed in terms of their tactile, visual and olfactory

background stimuli to keep them discriminably different. The skinner boxes used for context

A were scented with clove, lit by a house light mounted on the wooden cabinet and the floor

of each Skinner box was left uncovered.

Context B boxes were scented using peppermint, lit by a panel light above the food

receptacle and the floors were covered with metal grids.

The boxes were scented by putting 5 drops of either “Julia Lawless Aqua Oleum

Peppermint Oil” or “Julia Lawless Aqua Oleum Clove Bud Oil” in the waste tray, this oil was

replaced every session after the tray was cleaned (Bouton & King, 1983).

Design:

This study examined the effect of the temporal reconsolidation window on contextual

renewal of appetitive behaviours. The experiment was a (2 x 2) mixed measures design. The

dependent variables were active/inactive lever responses, head entries and time spent in the

receptacle during CS presentation period (CSPP) and non-CS periods (NCSP) and

cumulative CS presentation periods. The independent variables were the reactivation group

(RET30min and RET6hr) and the context (either ABA or ABB).

Acquisition of the operant behaviour is shown by an increase in dependent variables

across conditioning sessions. Extinction is shown by a decline in all appetitive behaviours

across sessions.

During testing the animals were either be returned to their conditioning context or

remained in their extinction context. For renewal to be shown, the ABA condition would

have shown higher rates of responding than in the ABB condition; there would be a

significant effect of context but not reactivation group. Conversely, for reconsolidation to be

shown the 30min group would have had lower rates of appetitive responding than the 6hr

group, with RET30min ABB showing the lowest rate of responding and RET 6hr ABA

showing the highest level of responding.

Procedure:

In order to reduce expressions of neophobia, the mice undertook brief (40 minutes

for 2 days) receptacle approach training before the experiment began. In this training, mice

were placed in the Context A (counterbalanced to Context B for half of the mice) with a

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syringe pump activated on a RI30 schedule [min=15seconds, max=45seconds] set to

deliver a small, of sucrose solution [approximately 50µl] into the receptacle.

Stage one: conditioning: For days 3 to 14, mice were placed in context A

(counterbalanced to context B for half of the mice) and partook in conditioning sessions.

Initially, these were 40 minutes in length but were reduced to 30 on day 5. During these

sessions, a tone was paired with 10% sucrose delivery (CS+) in 5 second intervals if the

active lever was pressed (active/inactive levers were counterbalanced). During the 5

second sucrose delivery period any additional lever pressers were ineffective. This was

then followed by a 5 second interval of no noise but active lever presses remained

ineffective. This 10 second interval will be referred to as the CS presentation period

(CSPP) and the remaining proportion of the session will be called the non-CS period

(NCSP).

Stage two: reactivation and extinction: From days 15 to day 21 the mice were separated

into two groups. Both groups experienced a 10 minutes retrieval trial in the extinction

context (Frankland et al., 2004). Group 1 (RET30min) then were returned to their homes

cages for 30 minutes, whereas Group 2 (RET6hr) were returned to their home cages for 6

hours, before they then conducted a 30 minute extinction session in context B

(counterbalanced to context A for half of the mice). During extinction, each lever press of

the active lever (counterbalanced for half of the mice) elicited CS+ presentation in the

absence of sucrose.

Stage three: test.: On day 22, the reactivation groups (RET6hr and RET30min) were

further divided into two groups; one of these groups was then given a conditioned

reinforcement test in the same context as their extinction occurred (ABB) [for example,

RET6hr ABB and RET30min ABB]. The other group was given a conditioned

reinforcement test in the same context as their conditioning occurred (ABA) [RET6hr

ABA and RET30min ABA].

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Figure 1: Summary of experimental procedure. Contexts A and B illustrated here were

counterbalanced for half the animals. (Illustrations adapted from Abel and Lattal, 2001)

Results

Mauchley‟s test revealed that the assumption of sphericity had been violated a number of

main effects for conditioning, reactivation and extinction and so was adjusted using either

Greenhouse-Geisser or Huynh-Feldt estimates of sphericity

Stage One: Conditioning

Figure 2: Mean rate (per minute) of reinforced lever presses during CS presentation

periods across conditioning sessions (i.e. 1-12) Error bars ± 1 SE. As the 12 conditioning

sessions progressed there was an increase in the mean rate of active lever presses per

minute followed by a head entry into the receptacle.

Figure 2 shows an increase in reinforced lever presses throughout conditioning. This was

confirmed by a repeated measures ANOVA showing a significant main effect of session on

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the rate of reinforced lever presses per minute, F(5.29, 158.59)= 44.52, p<.001. A post hoc

contrast revealed that the rate of CS presentations were significantly higher, F(1, 30)=155.71,

p<.001, r = .92, in the last session than the first. There was no difference between the

reactivation groups in the rate of reinforced lever presses, F(1, 30) =.006, p=.94.

Figure 3 Mean percentages of head entries into the receptacle during the CS presentation

period (CSPP) and the non-CS period (NCSP) across all conditioning sessions. Error bars ± 1

SE. This illustrates a change in behaviour conditioning as a function of training. From

session 8 onwards the animals entered the receptacle during the CSPP over 60% of the

time. Conversely, the number if head entries during the NCSP declined throughout the

sessions.

Figure 3 shows that session had a differential effect on head entries during the CSPP and

NCSP indicating that behaviour changed as a function of training. A two-way repeated

measures ANOVA revealed that there was no significant main effect of session, F(1.47,

44.10) =1.71, p=.20, suggesting session did not have the same effect on responding during

CSPP and NCSP. There was a significant main effect of stimulus presence (CSPP compared

to NCSP), F(1, 30)=15.05, p=.001. Therefore, the percentage of head entries during the

CSPP was significantly higher than NCSP head entries.

There was no significant difference between the 6hr and 30minute groups in their

percentage of head entries, F(1, 30) =13.45, p=.001.

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Importantly, there was a significant interaction between CSPP and session (1-12),

F(4.76, 142.87)=48.56, p<.001, indicating training altered the CS. A post hoc contrast

illustrated that as conditioning sessions progressed the percentage of head entries during the

CSPP was significantly higher than NCSP head entries, F(1, 30)=162.79, p<.001, r = .92

These results suggest across conditioning the animals differentiated between the

CSPP and NSPP; entering the receptacle during CSPP more than during NCSP.

Figure 4: Mean press rates per minute of active lever and inactive lever across

conditioning sessions (1-12). Error bars ± 1 SE. Portrays the change the rate of lever

pressings throughout the conditioning sessions (i.e. 1-12) for both the active and inactive

levers. Rate of active lever presses increased throughout the sessions whereas the rate of

pressing for the inactive lever did not change across sessions.

Figure 4 indicates that the rate of compressions on both levers changes as a function of

conditioning. A two-way repeated measures ANOVA revealed a significant main effect of

session, F (4.64, 139.08) =37.60, p<.001, suggesting session effected CSPP and NCSP

equivalently.

There was a significant main effect on press rate (per minute) of active and inactive

lever, F(1, 30) =159.37, p<.001. There was no significant difference between the reactivation

groups, F(1, 30) =.013, p=.91. Suggesting the active lever was pressed significantly higher

than the inactive lever by both RET30min and RET6hr.

There was a significant interaction between the session number and the rate of lever

pressing, F(4.93, 147.80) =36.22, p<.001. This suggesting both number and rate of lever

compressions varied with conditioning session. A post hoc contrast revealed as sessions

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progressed the active lever press rate was significantly higher than the inactive lever press

rate, F(1, 30)=158.62, p<.001, r = .92.

These results suggest that, with training, the levers could elicit differential responses and that

the animals pressed the active lever significantly more than the inactive lever indicating the

acquisition of the operant behaviour.

Stage Two: Reactivation and Extinction:

A: Reactivation

Following stage one (conditioning) the animals were split into two counter-balanced

conditions (RET6hr and RET30min). Each group underwent a brief ten minute reactivation

session either six hours (RET6hr) or thirty minutes (RET30min) before thirty minutes

extinction session (see figure 1 for a schematic).

Figure 5: Mean rate of lever presses on previously active lever per minute during CS

presentation period (CSPP), for reactivation groups RET6hr and RET30min, across

reactivation sessions (1-7). Error bars ± 1 SE. For both the RET60hr and RET30min group

the number of responses decreased throughout the sessions.

The rate of responding on the active lever during CSPP decreased as reactivation (sessions 1-

7) progressed; initially both reactivation groups show the same rate of responding but rate of

responding for group RET30min decreased more rapidly, and was consistently lower, than

RET6hr. This observation was confirmed by a two-way mixed measures ANOVA which

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revealed there was a significant main effect of session on the rate of reinforced lever presses

during CS presentations periods, F(2.94, 64.73)= 15.74, p<.001. A post hoc contrast revealed

that the rate of reinforced lever presses during CSPP were significantly lower, F(1, 22)

=44.94, p<.001, r = .82, in the last session than the first.

There was no significant interaction effect between the session and the reactivation

group, F(2.94, 64.73) =.834, p=.48. However, there was a significant main effect of group on

the rate of reinforced lever presses during CSPP, F(1, 22) =5.36, p<.05. This suggests that

the 30min group responded at a significantly lower rate than the 6hr group

Figure 6: Shows the percentage of head entries of the reactivation groups RET6hr and

RET30min during the CS presentation period (CSPP) and non-CS period (NCSP). Error bars ±

1 SE. Throughout the reactivation sessions the number of head entries in the CS

presentation period decreases. This decrease is more rapid in the RET6hr than the

RET30min group. For NCSP behaviour, in session one there is disparity in the behaviour

between the RET6hr and the RET30min groups. Both groups show a decline in this

behaviour as a function of reactivation.

Figure 6 shows the decrease in head entries during the CSPP as a function of the reactivation

sessions (1-7). A two-way mixed measures ANOVA which revealed that there was a

significant main effect of session on the percentage of head entries into the receptacle during

the CSPP, F(6, 132)= 5.304, p<.001. A post hoc contrast revealed that the percentage of head

entries during the CSPP was significantly lower, F(1,22)=25.76, p<.001, r = .73, in the last

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session than the first; suggesting that during stage two both reactivation groups equally

decreased in the percentage of head entries during the CSPP indicating the extinction of the

operant behaviour.

Throughout reactivation the percentage of head entries during the NCSP increases

for both reactivation groups. This observation was confirmed by a two-way mixed measures

ANOVA which showed a significant main effect of session on percentages of head entries

into the receptacle during non-CS period for both RET6hr and RET30min, F(6, 132)= 7.97,

p<.001. A post hoc contrast revealed a significant increase in this behaviour between the first

and last session, F(1, 22) =23.55, p<.001, r = .72.

The mean percentage of NCSP head entries declined equally for both reactivation

groups; suggesting the mice were becoming less accurate in their responding.

There was no significant effect of group on the percentage of NCSP, F(1, 22) =.67,

p=.42 or CSPP, F (1, 22) =.33, p=.57, head entries. Furthermore, there was no significant

interaction effect between the session and the reactivation group for NCSP, F(6, 132) =.90,

p=.50, or CSPP, F(6, 132) =.56, p=.76, head entries.

Figure 7: Mean rate (per minute) of lever presses on the previously active lever and

inactive lever during CS presentation period (CSPP), for reactivation groups RET6hr and

RET30min, across reactivation sessions (1-7). Error bars ± 1 SE. For both the RET60hr and

RET30min group the number of responses decreased throughout the sessions.

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In session one active lever press rates for both groups are similar but reactivation

progressed; the rate of responding for group RET30min decreased more rapidly, and was

consistently lower, than RET6hr. This observation was confirmed by a two-way mixed

ANOVA which revealed a significant main effect of session on the press rates of the

previously active lever during CSPP for both reactivation groups, F(2.29, 50.42)= 15.80,

p<.001. A post hoc contrast revealed that the lever press rates of the (previously) active lever,

for reactivation groups were significantly lower, F(1,22)=40.34, p<.001, r=.80, in the last

session than the first.

Both reactivation groups show a consistently low response rate on the inactive lever.

There is a small increase in this behaviour in session 5 but this quickly decreases by session

6. This observation was confirmed by a two-way mixed measures ANOVA that revealed

there was no significant main effect of session on the press rates of inactive lever, F(2.20,

48.43)=2.45, p=.09.

There was no significant main effect of reactivation group on the press rates of

inactive, F(1, 22) =.37, p=.55 or active lever, F(1, 22) =2.12, p=.16. There was no significant

interaction effect between the session and the reactivation group for inactive, F(2.20, 48.43)

=1.43, p=.25, or active lever press rates, F(2.20, 48.43) =1.43, p=.25.

The results from reactivation show a reduction in operant behaviour since condition

indicating the extinction of the appetitive behaviour.

B: Extinction.

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Figure 8: Mean rate of reinforced lever presses (per minute) of the previously-active lever

during CS presentations (CSPP) for RET6hr and RET30min across extinction sessions. Error

bars ± 1 SE. Both reactivation groups show a decline in behaviour but throughout the

sessions responding of the RET6hr group was lower than that of RET30min.

Figure 8 shows a gradual decrease in the rate (per minute) of compressions of the previously-

active lever during CS presentation across the extinction sessions for both reactivation

groups. A two-way mixed measures ANOVA confirmed that there was a significant main

effect of session on the rate of CS Presentations, F(3.38, 101.43) = 29.24, p<.001. A post hoc

contrast revealed that the rate of CS presentations was significantly lower, F(1, 30) =62.93,

p<.001, r = .82, in the last session than the first for both reactivation groups. This suggests

that although in the conditioning sessions the CS presentation rate was high the behaviour

was now becoming extinct as the extinction sessions (1-7) progressed.

There was a significant effect of group on the rate of CS presentations, F(1, 30)

=4.68, p<.05. The rate of presses (per minute) on the previously active lever during the CSPP

was significantly lower for RET6hr than RET30min. However, there was no significant

interaction effect between the session and the reactivation group, F(3.38, 101.43) =1.76,

p=.15.

0

0.5

1

1.5

2

2.5

1 2 3 4 5 6 7

Rate

of R

espo

nse/

min

Session

6hr 30min

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Figure 9: Shows the percentage of head entries during the CS presentation period (CSPP)

and non-CS period (NCSP) across extinction sessions for RET6hr and RET30min. Error bars ±

1 SE. The percentage of head entries during the CS interval decreased from the first

session indicating that the behaviour was changed as a function of extinction training (i.e.

sessions 1 -7).

Figure 9 indicates that head entry behaviour during CSPP was altered across the extinction

sessions. Both reactivation groups show a decline in the behaviour and whilst there was a

difference between these groups in session 1 it was gone by the last session, 7. A two-way

mixed measures ANOVA which revealed that there was a significant main effect of session

on the percentage of head entries into the receptacle during the CSPP, F(5.27, 157.97) =

4.56, p=.001. A post hoc contrast revealed that the percentage of CS head entries was

significantly lower for both groups, F(1, 30) =12.82, p=.001, r = .54, in the last session than

the first. This suggests during session 1 the mice were making head entries during the CSPP

but that as extinction carried on this behaviour diminished.

This figure also shows that the percentage of head entries into the receptacle during

NCSP changed as a function of extinction training; both reactivation groups show a

consistent increase throughout extinction. This observation was confirmed by a two-way

mixed measures ANOVA which revealed that there was a significant main effect of session

on the percentage of NCSP head entries into the receptacle, F(6, 180)= 4.72, p<.001. A post

hoc contrast revealed that the percentage of NCSP head entries was significantly higher, F(1,

30) =12.82, p=.001, r = .55, in the last session than the first for both reactivation groups.

0102030405060708090

100

1 2 3 4 5 6 7

Perc

enta

ge o

f Hea

d En

trie

s

Extinction Session

% of entries in NCSP RET6hr % of entries in NCSP RET30min

% of entries in CSPP RET6hr % of entries in CSPP RET30min

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This suggests that both reactivation groups showed a reduced accuracy in their

operant behaviour between the first and last extinction sessions.

There was no significant difference between the reactivation groups for NCSP,

F(1,30)=1.55, p=.22, or CSPP, F(1,30)=1.44, p=.24, on the percentage of head entries. There

was no significant interaction effect between the session and reactivation groups for the

percentage of head entries made during NCSP, F(6, 180)=1.20, p=.31, or CSPP, F(5.27,

157.97)=1.52, p=.18.

Figure 10: Mean compression rates (per minute) of previously active and inactive levers

across extinction sessions for RET6hr and RET30min. Error bars ± 1 SE. Both RET6hr and

RET30min, maintain low press rates per minute of the inactive lever until session 5 when

it increases marginally only for it to decrease in session 6. For the active lever, the press

rates per minute of both reactivation groups rapidly decreased until session 5 (when they

both increased) and then decreased rapidly again after that session

As shown in figure 10, the mean lever press rate per minute of the previously active lever

changed as a function of training (i.e. sessions 1 to 7) but there was little difference between

RET30min and RET6hr. This observation was confirmed by a two-way mixed measures

ANOVA which revealed that there was a significant main effect of session on the rate of

active lever presses per minute, F(2.14. 64.12)= 26.12, p<.001. A post hoc contrast revealed

that the rate of active lever presses per minute were significantly lower, F(1, 30) =46.92,

p<.001, r = .78, in the last session than the first session for both reactivation groups.

0

1

2

3

4

5

6

1 2 3 4 5 6 7

Leve

r Pre

ss R

ate/

min

Extinction Session

Inactive RET6hr Inactive RET30min Active RET6hr Active RET30min

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The press rate (per minute) for the inactive lever changed as a function of extinction

training (i.e. sessions 1 to 7) but this did not differ between reactivation groups; a two-way

mixed measures ANOVA confirmed there was a significant main effect of session on the rate

of inactive lever presses per minute, F(3.37, 101.01)= 12.67, p<.001. A post hoc contrast

revealed that the rate of inactive lever presses per minute was not significantly different, F(1,

30) =3.25, p=.08, r=.31, in the last session than the first session for RET30min and RET6hr.

This suggests that both reactivation groups pressed the inactive lever at an equal, low rate

across sessions.

There was no significant effect of reactivation group on the rate of active lever

presses per minute, F(1, 30) =2.97, p=.10, or the rate of inactive lever presses per minute,

F(1, 30) =1.09, p=.31. There was no significant interaction effect between the session and the

reactivation group for either active lever press rate, F(2.14, 64.12) =1.47, p=.24, or the rate

of inactive lever presses (per minute), F(3.37, 101.01) =1.70, p=.17.

The results from stage 2 show a decline in appetitive behaviours (i.e. lever presses and head

entries) as a function of training.

Stage 3: Tests.

Stage 3 involved RET6hr and RET30min being split; half the animals were returned to their

original conditioning context (ABA) and the other half were returned to their extinction

context (ABB) (for a schematic see Figure 1). Reconsolidation will have occurred if

RET30min show lower rates of appetitive behaviours than the RET6hr group. Renewal

would be shown if animals in ABA would show higher levels of appetitive behaviour than

ABB mice.

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Figure 11: The mean rate of reinforced lever presses per minute during CS presentation

periods (CSPP) for reactivation groups RET6hr and RET30min in context ABB and ABA.

Error bars ± 1 SE.

Figure 11 shows the mean rate of active lever presses during CSPP was higher in context

ABA than in context ABB, however, there is no difference in rates of active lever presses

between RET6hr and RET30min; suggesting renewal. This observation was confirmed by a

two-way mixed measures ANOVA which revealed that there was a significant difference

between contexts ABA and ABB, F(1,30)=18.69, p=.001, but no significant effect of

reactivation group, F(1,30)=.001, p=.97. This suggests renewal of active lever pressing

during CSPP for both reactivation groups but that reconsolidation did not occur. There was

no significant interaction effect between context and the reactivation group, F(1, 30) =.44,

p=.05.

0

0.5

1

1.5

2

2.5

6hrs 30min

Rate

/min

Reactivation Group

CS Presentations ABB CS Presentations ABA

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Figure 12 shows rate (per minute) of compression of the previously active lever for

reactivation groups (RET30min and RET6hr) in context ABB and ABA. Error bars ± 1 SE.

Figure 12 shows a difference in the rate (per minute) of reinforced lever presses during the

CSPP between contextual but not reactivation groups. This observation was confirmed by a

two-way mixed measures ANOVA which revealed that there was a significant difference

between contexts, F(1, 30) =22.68, p<.001, but no significant effect of reactivation group,

F(1, 30) =.002, p=.96, on lever press rate. This indicates that renewal occurred for both

contextual groups but that reconsolidation did not occur for the mean lever press rates of the

previously active lever.

There was no significant interaction between reactivation group and context, F(1, 30)

=.45, p=.51.

0

0.5

1

1.5

2

2.5

6hrs 30min

Leve

r Pre

sses

/min

Reactivation Group

Active Lever Presses ABB Active Lever Presses ABA

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Figure 13: Mean rate of inactive lever presses per minute for reactivation groups RET6hr

and RET30min, in context ABB and context ABA. Error bars ± 1 SE.

Figure 13 suggests there is no difference in rate of compressions across contextual groups or

reactivation group. This observation is confirmed by a two-way mixed measures ANOVA

which revealed that there was no significant difference between contexts ABA and ABB,

F(1,30)=.082, p=.78 and no significant effect of reactivation group, F(1,30)=1.48, p=.23.

This indicates that there was no renewal or reconsolidation effect on the inactive lever

suggesting that only behaviour that mediates the CS is subject to renewal. Furthermore, there

was no interaction effect between context and the reactivation group, F(1, 30)=.60, p=.45.

0

0.5

1

1.5

2

2.5

6hrs 30min

Leve

r Pre

sses

/min

Reactivation Group

Inactive Lever Presses ABB Inactive Lever Presses ABA

0

10

20

30

40

50

60

70

80

90

100

6hrs 30min

Pere

cent

age

of h

ead

entr

ies t

o m

agaz

ine

Reactivation Group

Magazine Entries During CSPP ABB Magazine Entries During CSPP ABA

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Figure 14: Mean percentage of head entries to the receptacle made during CS presentation

period (CSPP) for RET6hr and RET30min in context ABB and ABA. Error bars ± 1 SE. This

graph suggests a difference in contextual but not reactivation group.

Figure 14 shows the percentage of head entries into the receptacle during the CSPP were

higher in ABA than in ABB, suggesting renewal, but no apparent difference between

reactivation groups. This observation was confirmed by a two-way mixed measures ANOVA

which revealed that there was a significant difference between contexts ABA and ABB,

F(1,30)=11.75, p<.01 but no significant effect of reactivation group, F(1,30)=.11, p=.74. This

suggests that the renewal effect occurred for head entries during the CSPP for both

contextual groups but also that reconsolidation did not occur for head entries during the

CSPP. There was no significant interaction effect between context and the reactivation group,

F(1, 30) =.82, p=.37.

Figure 15 Mean percentages of entries to the receptacle made during non-CS period

(NCSP) in context ABB and ABA for reactivation groups RET6hr and RET30min. Error bars ±

1 SE.

Figure 15 shows that the percentage of head entries into the receptacle during the NCSP was

higher for group ABB than ABA but this behaviour did not differ across reactivation groups.

This observation was confirmed by a two-way mixed measures ANOVA which revealed that

there was a significant difference between contexts ABA and ABB, F(1,30)=14.69, p<.001

but no significant effect of reactivation group, F(1,30)=.38, p=.54. This suggests that the

0

10

20

30

40

50

60

70

80

90

100

6hrs 30min

Pere

cent

age

of h

ead

entr

ies t

o m

agaz

ine

Reactivation Group

Magazine Entries NCSP ABB Magazine Entries NCSP ABA

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renewal effect occurred for head entries during non-CS periods for both contextual groups

but that reconsolidation did not occur for head entries during NCSP.

There was no significant interaction effect between context and the reactivation

group, F(1, 30) =.23, p=.64.

Figure 16: the mean amount of time (per minute) spent in the receptacle during CS

presentation periods (CSPP) in context ABB and ABA by reactivation groups RET6hr and

RET30min. Error bars ± 1 SE.

According to figure 16, context had a differential effect on time spent in receptacle during the

CSPP; animals in ABA spent more time in the receptacle than those in ABB. This

observation was confirmed by a two-way mixed measures ANOVA showing a significant

difference between ABA and ABB, F(1,30)=21.46, P<.001, suggesting a renewal effect for

the mean time spent in receptacle during CSPP for both contextual groups.

However, this behaviour was not significantly affected by reactivation group; F(1, 30)

=.001, p=.98. This suggests that reconsolidation did not occur for the time spent in receptacle

during CSPP.

There was no significant interaction effect between context and the reactivation

group, F(1, 30) =.21, p=.65

0

1

2

3

4

5

6

6hrs 30min

Tim

e in

mag

/min

Reactivation Group

Time in Magazine during CSPP ABB Time in Magazine during CSPP ABA

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Figure 17 compares the mean amount of time (per minute) spent in the receptacle in non-

CS periods (NCSP) in context ABB and ABA by reactivation groups RET6hr and RET30min.

Error bars ± 1 SE.

The time spent in the receptacle during NCSP was low and stable for both contextual and

reactivation conditions. A two-way mixed measures ANOVA confirmed no significant

difference in time spent in receptacle during NCSP between contexts ABA and ABB,

F(1,30)=1.17, p=.29 and no significant effect of reactivation group, F(1,30)=.02, p=.88. This

suggests that neither renewal nor reconsolidation occurred for the time spent in receptacle

during NCSP. There was no significant interaction effect between context and the

reactivation group, F(1, 30) =3.66, p=.07.

The results reflect a difference of contextual but not reactivation conditions, meaning renewal

but not reconsolidation was shown. Renewal was shown for reinforced lever presses during

CSPP, press rate of (previously) active lever, head entries during the CSPP and NCSP, and

time spent in receptacle during the CSPP. Reactivation conditions did not affect any results

meaning reconsolidation was not shown for behaviours.

0

1

2

3

4

5

6

6hrs 30min

Tim

e in

mag

/min

Reactivation Group

Time in Magazine NCSP ABB Time in Magazine NCSP ABA

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Discussion

During stage one; there was an increase in rate of active lever presses per minute and

head entries during CSPP. Conversely, the percentage of head entries into the receptacle and

active lever presses during NCSP dropped. The animals demonstrated discrimination

between the active and inactive levers: as a function of training active lever presses increased

but inactive lever presses decreased. There was no significant difference between reactivation

or contextual groups at any point during conditioning showing that behaviour was changing

only as a function of training. These results suggest that the mice were discriminating

between the CSPP and NCSP and between the inactive and active levers. This indicates they

had developed the operant behaviour as a function of conditioning training.

During stage two, behavioural changes included a decrease in the number of head

entries and lever presses during CSPP and NCSP. This suggests the mice were having their

previously acquired behavioural repertoire extinguished, reducing the accuracy of their

responding. Throughout reactivation there was no significant effect of contextual or

reactivation groups indicating behaviour was changing only as a function of training.

Stage three of the experiment indicated a renewal of the following conditioned

appetitive behaviours: rate of head entries and lever press rates of the previously active lever

during the CSPP, time spent in the receptacle during CSPP. Response rates during NCSP

remained low as did inactive lever press rates (per minute).

The renewal of the operant behaviour conditioned in stage one supports previous

research (Bossert et al 2006) and confirms the hypothesis that context can mediate appetitive

behaviours.

However, results indicated no significant difference of reactivation groups; the fact

that the behaviours did not alter as a function of time indicates that reconsolidation was not

shown. This result is contrary to our second prediction that a reactivation of conditioning

contexts would affect appetitive behaviours post-extinction. This finding is opposed to

previous research which used temporal reactivation as an amnestic treatment in

reconsolidation (Monfils et al. 2009).

Although this study reactivated, disrupted and tested the memory within the labile

period, thus fulfilling the criteria for reconsolidation described by Lewis et al. (1968),

reconsolidation may still have been disrupted by boundary conditions (Lewis, 1969; Gordon

& Spear, 1973). According to Nader & Einarsson (2010), boundary conditions are explicit

parameters which stop the reconsolidation of memories in physiological or experimental

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conditions in which it would ordinarily occur. Examples of boundary conditions, explored by

other studies, include: memory age (Alberini & Milekic 2002, Hardt & Nader, 2009; Tronson

& Taylor, 2007; Morris & Wang, 2010), intensity of conditioning (Frankland et al., 2004)

and level of extinction memory consolidation (Eisenberg, Kabilo, Bernam & Dudai 2003;

Pedreira & Maldonado, 2003).

According to Debeic, LeDoux & Nader (2003), extinction can be thought of as a

boundary condition: reconsolidation only occurs when extinction is not induced (Eisenberg et

al.2003, Nader 2003). It has been suggested that only a few or weak retrieval trials, that do

not result in extinction, lead to reconsolidation (Eisenberg et al., 2003, Pedreira &

Maldonado, 2003; Berlau et al 2000; Frankland et al 2004, Fischer et al. 2004).

Our reactivation sessions occurred over a number of days and showed a gradual

decrease in the operant behavioural repertoire. Furthermore, it might be proposed that, after a

prolonged time of no reward availability in either context, animals are no longer able to

remember which environment was associated with reward, and that the responding at test

reflects spontaneous recovery of the extinguished responding (Rescorla 2004). Moreover, it

has been suggested that consolidated memories might be triggered for reconsolidation as part

of memory updating i.e. when the current information is discrepant to the stored memory

trace (Morris &Wang 2010). Earlier studies show that in animal studies novelty detection is

high in new contexts (Barnes, Good, Honey, McGregor & Staal, 2007). We can assume that

short reactivation periods would increase the novelty detection during reactivation sessions

and so potentially elicit memory updating.

Another possible reason for a failure to show reconsolidation in this experiment is the

lack of emotional arousal during training and extinction. Mueller & Cahill (2010) assert that

nor-adrenaline strengthens consolidation in both appetitive and aversive learning via β-

receptor signalling. On a neuronal level, nor-adrenaline increases excitability which in turn

enhances synaptic plasticity. Administration of adrenaline has been shown to enhance

memory consolidation in animals and humans (Gold, van Buskirk, & Haycock, 1977).

Furthermore, context induced sucrose seeking has been shown to be disrupted by β-

adrenergic antagonists (Diegaarde, Schoffelmeer, & De Vries 2006). Previous research has

shown that anxious individuals are more sensitive to context and have greater contextual

awareness than calmer counterparts (Grillon et al., 2002). As Monfils et al., (2009) study was

done using aversive/shock conditioning this would have lead to a stress response and, thus,

nor-adrenaline release. The paradigm used in this study used no aversive stimuli, meaning no

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stress, and consequently no adrenaline or β-adrenergic response was induced; potentially

explaining why reconsolidation failed to take place.

One final criticism of reconsolidation research in general is that there is no universal

reactivation protocol which satisfactorily induces plasticity of consolidated memories (Nader

2007). Therefore, we can assume that slight parametric differences could influence

disruption of reconsolidation (Tronson & Taylor 2006). It would be beneficial for a

procedural criterion to be amalgamated with those of Lewis et al. (1968). Furthermore,

research exploring the effect of nor-adrenaline on reconsolidation (potentially Yohimbine

which induces a stress response) would be invaluable; particularly for research exploring

anxiety disorders. Finally, it is unclear whether reconsolidation represents a loss of memory

or difficulty with retrieval (Nader & Einarsson, 2010). Wang, de Oliveira Alvares and Nader

(2009) suggest that in order to truly change memory we must first understand the inhibitory

effect of boundary conditions on a molecular level, and thus, be able to harness them

therapeutically.

In conclusion, although this study failed to explicitly demonstrate reconsolidation of

appetitive behaviours it provides valuable insight into areas of future research and

mechanisms that, potentially, mediate reconsolidation.

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References:

Abel, T. & Lattel, K. M. (2004) Behavioural impairments caused by injections of the protein

synthesis inhibitor anisomycin after contextual retrieval reverse with time

Proceedings of the National Academy of Sciences of the United States of America,

101, 13 4667–4672

Acosta, J., Boynton, F. Kirschner, K.& Neisewander, J. (2005) Stimulation of 5-HT1B

receptors decreases cocaine- and sucrose-seeking behaviour Pharmacology,

Biochemistry and Behaviour, 80, 297–307

Aicardi, Burattini, Janak & Zironi (2006) Context is a Trigger for Relapse to Alcohol

Behavioural Brain Research, 167,150–155

Akirav, I., Marou, M.& Raizel, H. (2006) Enhancement of Conditioned Fear Extinction by

Infusion of the GABAAagonist Muscimol into the Rat Prefrontal Cortex and

Amygdala European Journal of Neuroscience,23,3, 758–764,

Alberini, C. M& Milekic, M. H. (2002) Temporally graded requirement for protein synthesis

following memory reactivation. Neuron 36, 521–525

Alonso J, Angermeyer MC, Bernert S, Bruffaerts R, Brugha IS, Bryson H, de Girolamo G, de

Graaf R, Demyttenaere K, Gasquet I, Haro JM, Katz SJ, Kessler RC, Kovess V,

Lepine JR, Ormel J, Polidori G, Russo LJ, Vilagut G, Almansa J, rbabzadeh-

Bouchez S, Autonell J, Bernal M, Buist-Bouwman MA, Codony M, Domingo-

Salvany A, Ferrer M, Joo SS, Martinez- Alonso M, Matschinger H, Mazzi F,

Morgan Z, Morosini R, Palacin C, Romera B, Taub N, ,lebergh WAM.

(2004)Prevalence of mental disorders in Europe: results from the European Study of

the Epidemiology of Mental Disorders (ESEMeD) project. Acta Psychiatrica

Scandinavica 109: 21–27

11510

32


Anokhin, K. V., Tiunova, A. A., & Rose, S. P. R. (2002). Reminder Effects- Reconsolidation

or Retrieval Deficit? Pharmacological Dissection with Protein Synthesis Inhibitors

Following Reminder for a Passive-Avoidance Task in Young Chicks. European

Journal of Neuroscience, 15(11), 1759-1765.

Avena, N. M., Hoebel, B.G. and Rada, P (2005) Daily Bingeing on sugar repeatedly releases

Dopamine into the accumbens shell , Neuroscience 134 737-744

Barnes P., Good MA, Honey R.C., McGregor, A. & Staal V (2007) Context- but not

familiarity-dependent forms of object recognition are impaired following excitotoxic

hippocampal lesions in rats. Behavioural Neuroscience 121:218–23

Bernstein GA. & Victor AM (2009) Anxiety disorders and posttraumatic stress disorder

update. Psychiatric Clinics of North America 32: 57– 69

Berlau, D. McGaugh, J.L, Power, A. and Steward, O. (2006) Anisomycin infused into the

hippocampus fails to block “reconsolidation” but impairs extinction: The role of re-

exposure duration Learning and Memory 13:27-34

Bjorklund, A., Fischer, W., Gage F.H., Peterson, G.M., Varon, S., Wictorin, K. &

Williams, L.R.(1986) Continuous infusion of nerve growth factor prevents basal

forebrain neuronal death after fimbria fornix transaction Proceedings of the

National Academy of Science of the United States of America , 88, 23 9281-9285

Bouton, M. E. (1984). Differential Control by Context in the Inflation and Reinstatement

Paradigms. Journal of Experimental Psychology: Animal Behaviour Processes, 10,

56-74.

Bouton, M.E., (1988) context and ambiguity in the extinction of emotional leaning:

Implications for exposure therapy Behaviour Research and Therapy,26, 2, 137- 139

Bouton, M. E., (1993) Context, time, and memory retrieval in the interference paradigms of

Pavlovian learning. Psychological Bulletin ,14, 1; 80-99

11510

33


Bouton ME.(2002) Context, ambiguity, and unlearning: sources of relapse after behavioral

extinction. Biological Psychiatry;52:976–86

Bouton, M.E., Vurbic, D., and Woods, A. (2006) D-Cycloserine facilitates context-specific

fear extinction learning Neurobiology of Learning and Memory 90, 3, 504-510

Bouton ME (2011) Learning and the persistence of appetite: Extinction and the motivation to

eat and overeat Physiology & Behavior 103 51–58

Bouton, M. E, & Bolles. R. C. (1979). Contextual Control of the Extinction of Conditioned

Fear. Learning and Motivation, 10(4), 445-466.

Bouton, M.E & King, D., (1983) Contextual Control of the Extinction of Conditioned Fear:

Tests for the Associative Value of the Context Journal of Experimental Psychology,

Animal Behavior Processes, 9, 3, 248-265

Bouton, M.E., Gutiérrez, Moody & Zilski (2006), Extinction in multiple contexts does not

necessarily make extinction less vulnerable to relapse Behaviour Research and

Therapy; 44, 983–994

Bouton, M.E., and Moody, E. (2004) Memory processes in classical conditioning

Neuroscience and Biobehavioral Reviews 28, 663–674

Bouton, M. E., & Ricker, S. T. (1994). Renewal of Extinguished Responding in a Second

Context. Animal Learning and Behavior, 22(3), 317-324.

Bouton, M.E. &Swartzentruber, D. (1986) Associative and Occasion-Setting Properties of

Contexts Participating in a Pavlovian Discrimination Journal of Experimental

Psychology: Animal Behavior Processes, 12, 333-350

11510

34


Bouton, M.E. &Swartzentruber, D. (1991) Source of Relapse after extinction in Pavlovian

and Instrumental Learning Clinical Psychology Rmm, ,. 11, 123-140,

Bossert, J.M., Gray, S.M., Lu, L., Shaham, Y., (2006) Activation of Group II Metabotropic

Glutamate Receptors in the Nucleus Accumbens Shell Attenuates Context-Induced

Relapse to Heroin Seeking Neuropsychopharmacology 31, 2197–2209

Bruce SE, Yonkers KA, Otto MW, Eisen JL, Weisberg RB, Pagano M, Shea MT, KellerMB

(2005) Influence of psychiatric comorbidity on recovery and recurrence in

generalized anxiety disorder, social phobia, and panic disorder: a 12-year

prospective study. American Journal of Psychiatry 162:1179 –1187.

Cahill, S. and Mueller, D. (2010) Noradrenergic modulation of extinction learning and

exposure therapy Behavioural Brain Research 208; 1–11

Chevere, I., Josselyn, H., Kida,S., Kogan,J., Masushige, S., Peña de Ortiz, S., & Silva A.

(2002) CREB required for the stability of new and reactivated fear memories.

Nature Neuroscience; 5: 348–355.

Chiu WT, Demler O, Kessler RC, Merikangas KR, Walters EE.(2005) Prevalence, severity,

and comorbidity of 12-month DSM-IV disorders in the National Comorbidity

Survey Replication. Archives of General Psychiatry 62: 617–627

Collingwood, Jamieson, Macdonald, Pudney & Tinsley (2005) Measuring the harm from

illegal drugs using the Drug Harm Index. Home Office Online Report 24/05

Conklin, C. A., & Tiffany, S. T. (2001). The Impact of Imagining Personalized Versus

Standardizes Urge Scenarios on Cigarette Craving and Automatic Reactivity.

Experimental and Clinical Psychopharmacology, 9(4), 399-408

Contoreggi, C., Kimes, A.S., London, E.D., Grant, S., Liu, X., Margolin, A., Newlin, D.B.,

Phillips, R.L. (1996) Activation of memory circuits during cue-elicited cocaine

craving Proceedings of the National Academy of Sciences of the United States of

America 93, 21 12040-12045

11510

35


Crombag, H., Grimm, J. W., & Shaham, Y. (2002). Effect of Dopamine Receptor

Antagonists on Renewal of Cocaine Seeking by Reexposure to Drug-Associated

Contextual Cues. Neuropsychopharmacology, 27, 1007-1016.

Crombag, H. S., & Shaham, Y. (2002). Renewal of Drug Seeking by Contextual Cues After

Prolonged Extinction in Rats. Behavioral Neuroscience, 116, 169-173

Dankiewicz LA, Gracy KN, Koob GF, Weiss F (2000). Heroinspecific stimuli reinstate

operant heroin-seeking behavior in rats after prolonged extinction. Pharmacology

Biochemical Behaviour 65: 489–494.

Dębiec, J., Doyère, V., Nader, K., & LeDoux, J. E. (2006). Directly Reactivated, But Not

Indirectly Reactivated, Memories Undergo Reconsolidation in the Amygdala.

Proceedings of the National Academy of Sciences of the United States of America,

103(9), 3428-3433.

Debiec, J., LeDoux, J.E., and Nader, K. (2002). Cellular and systems reconsolidation in the

hippocampus. Neuron 36, 527–538

Denniston JC Gunther LM, Miller RR (1998). Conducting exposure treatment in multiple

contexts can prevent relapse. Behavioural Research Therapy 36: 75–91.

Department of Health and the National Treatment Agency (2010) Statistics from the National

Drug Treatment Monitoring System (NDTMS) 1 April 2009 – 31 March 2010

Diergaarde, L., Schoffelmeer, A.N.M., and De Vries, T.J. (2006) Adrenoreceptor mediated

inhibition of long-term reward-related memory reconsolidation. Behavioural Brain

Research. 170: 333–336.

Dudai, Y. (2004) The Neurobiology of Consolidations or how stable is the engram? Annual

Review in Psychology. 55:51–86

11510

36


Dudai, Y., and Morris, R.G.M. (2000). To consolidate or not to consolidate: what are the

questions? In: Brain, Perception, Memory. Advances in Cognitive Sciences, J.J.

Bulhuis, ed. (Oxford: Oxford University Press), pp. 149–162

Duvarci S, LeDoux JE, Nader K. (2008) De novo mRNA synthesis is required for both

consolidation and reconsolidation of fear memories in the amygdala. Learning and

Memory 15: 747–755,

Einarsson, E.Ö. & Nader, K. (2010) A bridge over troubled water: reconsolidation as a link

between cognitive and neuroscientific memory research traditions Annual review of

psychology, 61, 141-67

Eisenberg, M., Kobilo, T., Berman, D. E., & Dubai, Y. (2003). Stability of Retrieved

Memory: Inverse Correlation with Trace Dominance. Science, 301(5636), 1102-

1104.

Eisenhardt, D., Menzel, R. & Stollhoff,. (2008) One retrieval trial induces reconsolidation in

an appetitive learning paradigm in honeybees (Apis mellifera) Neurobiology of

Learning and Memory 89, 419–425

Ettenberg A and McFarland K, (1997). Reinstatement of drug-seeking behavior produced by

heroin-predictive environmental stimuli. Psychopharmacology 131: 86–92.

Everitt, B.J,. Milton, A.M. & Lee, J.L. (2006) Reconsolidation and Extinction of Conditioned

Fear: Inhibition and Potentiation, The Journal of Neuroscience, 26(39) 10051-10056

Fischer A, Sananbenesi F, Schrick C, Spiess J, Radulovic J. (2004) Distinct roles of

hippocampal de novo protein synthesis and actin rearrangement in extinction of

contextual fear. The Journal of Neuroscience, 24:1962–66

11510

37


Frankland, P.W.& Bontempi, B. (2005) The organization of recent and remote memories.

National Review of Neuroscience, 6:119–130

Frankland, P., Josselyn, .S., Kida, S Masushige, S., Silva, A.& Suzuki, A., (2004) Memory

Reconsolidation and Extinction Have Distinct Temporal and Biochemical Signatures

The Journal of Neuroscience, 24(20):4787– 4795

Freeman, F.M., Rose, S.P.R. and Scholey A.B. (1995). Two Time Windows of Anisomycin-

Induced Amnesia for Passive Avoidance Training in the Day-Old Chick,

Neurobiology of Learning and Memory , 63, 3, 291-295

Glickman, S. (1961) Perseverative neural processes and consolidation of the memory trace.

Psychological Bulletin, , 58(3), 218-233

Gold, P.E., van Buskirk, R., and Haycock, J.W. 1977. Effects of post-training epinephrine

injections on retention of avoidance training in mice. Behaviour and Biology. 20:

197–204.

Gomez,R..Hardt,O, Hupbach,A.R.& Nadel.L. (2007).Reconsolidation of episodic memories:

a subtle reminder triggers integration of new information. Learning and Memory.

14: 47–53.

.

Gordon, W. C. & Spear, N. E. (1973).The effects of strychnine on recently acquired and

reactivated passive avoidance memories. Physiology of Behaviour. 10, 1071–1075

Gordon, l., Tinsley, l., Godfrey, C. and Parrott, S. (2006) the economic and social costs of

Class a drug use in england and Wales, 2003/04, In Singleton, N., Murray, R. and

Tinsley, L. (eds) „Measuring different aspects of problem drug use: methodological

developments.‟ Home Office Online Report 16/06

Grillon, C. (2002) Startle reactivity and anxiety disorders: aversive conditioning, context, and

neurobiology Biological psychiatry, 52, 10. 958-975

11510

38


Kelley, A. E., & Berridge, K. C. (2002). The Neuroscience of Natural Rewards: Relevance to

Addictive Drugs. The Journal of Neuroscience, 22(9), 3306-3311.

Lewis, D., R.R. Miller, and J.R. Misanin. 1968. Control of retrograde amnesia. Journal of

Comparative & Physiological Psychology 66: 48–52.

Mactutus, C.F., R.L. Smith, and D.C. Riccio. 1980. Extending the ACTH-induced memory

reactiviation in an amnestic paradigm. Physiology and Behaviour 24: 541–546.

Mark, R.F. and Watts, M.E. (1971) Drug Inhibition of Memory Formation in Chickens. II.

Short-Term Memory Proceedings of the Royal Society ,. 178 no. 1053 455-464

McGaugh JL. 1966. Time-dependent processes in memory storage. Science 153:1351–58

McGaugh, J. L. (2000) Memory--a Century of Consolidation Science 14, ,. 287 no. 5451 pp.

248-251

Nader K,. & Hardt, O. (2009).A single standard for memory: the case for reconsolidation.

National Review Neuroscience 10: 224–234,

McLellan, A. T., & McKay, J. R. (1998). Components of Successful Treatment Programmes:

Lessons from the Research Literature. In A. W. Graham & T. K. Schultz (Eds.),

Principles of Addiction Medicine (pp.327-343): American Society of Addiction

Medicine.

Misanin JR, Miller RR, Lewis DJ (1968) Retrograde amnesia produced by electroconvulsive

shock after reactivation of a consolidated memory trace. Science 160:554 –555.

Monfils, M-H., Cowansage, K. K., Klann, E., & LeDoux, J. E. (2009). Extinction-

Reconsolidation Boundaries: Key to Persistent Attenuation of Fear Memories.

Science, 324(5929), 951-955

11510

39


Morris and Wang (2010) Hippocampal-neocoritcak interactions in memory formation,

consolidation and reconsolidation, Annual Review of Psychology, 62: 49-79

Nader, K. (2003). Memory Traces Unbound. Trends in Neurosciences, 26(2), 65-72.

Nader, K. (2007) A single Standard for Memory; the case for Reconsolidation Debates in

Neuroscience , 1 , 1 2-16

Nader, K., Schafe, G. E., & LeDoux, J. E. (2000). Fear Memories Require Protein Synthesis

in the Amygdala for Reconsolidation After Retrieval. Nature, 406, 722-726

National Treatment Agency Media Release (2009) Moves to provide greater protection to

children living with drug addicts

Nelson JB. (2002) Context specificity of excitation and inhibition in ambiguous stimuli.

Learning and Motivation;33:284–310.

Olausson,P., Quinn, J., Taylor, J. & Torregrossa, M. (2009) Targeting extinction and

reconsolidation mechanisms to combat the impact of drug cues on addiction

Neuropharmacology 56 186–195

Pavlov, I. P. (1927). Conditioned Reflexes. Oxford, UK: Oxford University Press.

Pedreira, M. E., Pérez-Cuesta, L. M., & Maldonado, H. (2002). Reactivation and

Reconsolidation of Long-Term Memory in the Crab Chasmagnathus: Protein

Synthesis Requirement and Mediation by NMDA-Type Glutamatergic Receptors.

The Journal of Neuroscience, 22(18), 8305-8311

Pederia, M.E. &H.Maldonado. (2003). Protein synthesis subserves reconsolidation or

extinction depending on reminder duration. Neuron 38: 863–869.

Quirk GJ, Russo GK, Barron JL, Lebron K: (2000) The role of ventromedial prefrontal

cortex in the recovery of extinguished fear. Journal of Neuroscince, 20:6225-6231.

11510

40


Rescorla, R. (2001). Experimental extinction. In R. R. Mowrer, & S. B. Klein (Eds.),

Handbook of contemporary learning theories (pp. 119–154). Mahwah, NJ: Erlbaum.

Rescorla RA. (2004) Spontaneous recovery. Learning and Memory;11:501–9.

Robinson and Yager (2010) Cue-induced reinstatement of food seeking in rats that differ in

their propensity to attribute incentive salience to food cues, Behavioural Brain

Research 214 30–34

Rose, J. and Rankin, C. (2006) B locking Memory Reconsolidation Reverses Memory-

Associated Changes in Glutamate Receptor Expression The Journal of

Neuroscience, 8, 26(45): 11582-11587

Sara, S.J. 1973. Recovery from hypoxia and ECS induced amnesia after a single exposure to

the training environment. Physiology and Behaviour 9: 85–89.

Sara, S. (2000). Retrieval and reconsolidation: toward a neurobiology of remembering.

Learning and Memory. 7, 73–84.

Schafe, G. E., & LeDoux, J. E. (2000). Memory Consolidation of Auditory Pavlovian Fear

Conditioning Requires Protein Synthesis and Protein Kinase A in the Amygdala. The

Journal of Neuroscience, 20:RC96, 1-5.

Schiller ,D. , Vicentic, A., Monfil, M., Paré, D., Quirck, G. And Herry, C. (2010) Erasing

Fear Memories with Extinction Training The Journal of Neuroscience,

30(45): 14993-14997

Schiller, D., Levy, I., Niv, Y., LeDoux, J., Phelps, E. (2008) From Fear to Safety and Back:

Reversal of Fear in the Human Brain, The Journal of Neuroscience, 28(45): 11517-

11525

11510

41


Stewart J, de Wit H, Eikelboom R (April 1984). "Role of unconditioned and conditioned

drug effects in the self-administration of opiates and stimulants". Psychological

Review 91 (2): 251–68

Tronson, N.C & Taylor, J.R (2006) molecular mechanisms of memory reconsolidation,

Nature reviews Neuroscience 8 262-275

Volkow, N. D., Wang, G-J., Telang, F., Fowler, J.S., Logan, J., Childress, A. R, Jayne, M.,

Ma, Y., & Wong, C. (2006) Cocaine Cues and Dopamine in Dorsal Striatum:

Mechanism of Craving in Cocaine Addiction The Journal of Neuroscience,

26(24):6583-6588

Walker, M. P., Brakefield, T., Hobson, J. A. & Stickgold, R., (2003) Dissociable stages of

human memory consolidation and reconsolidation, Nature 425, 616–620

Wang, S.H., L. de Oliveira Alvares & K. Nader. 2009. Cellular and systems mechanisms of

memory strength as a constraint on auditory fear reconsolidation. Nature

Neuroscience. 12: 905–912.

Weisberg RB.(2009) Overview of generalized anxiety disorder: epidemiology, presentation,

and course. Journal of Clinical Psychiatry 70: 4 –9

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SCHOOL OF PSYCHOLOGY

ETHICS FORM FOR RESEARCH WITH ANIMALS PART A

Your name

Kate Doran

Supervisor

Hans Crombag

Project Title

Using Reconsolidation to Enhance

Contextual Extinction

Degree programme (for example BSc,

MRes)

Psychology BSc

Please answer the following questions: In addition to indicating “yes” or “no” for each question, please type in additional

explanatory information where appropriate

1. Please specify the animal species and number to be observed

(please add rows as required).

Species Name Common Name Wild or Captive Number

Mus musculus Mice Captive 16

* if numbers are not known please indicate an estimate or expected number

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2. Does any of the species listed above have special protection/endangered

status?

NO

If yes, provide details of the permits/permissions that have been

sought/obtained:

3. Where will the study be carried out (please provide details of the location of the

study, or state that it will be carried out in the University’s animal holding

facility):

The study will be carried out at the University of Sussex Animal Research Laboratory.

Where appropriate, I have contacted the owner/ manager of the location and

I have attached evidence to confirm their approval for the project.

4. Observation studies with minor interference: Can you confirm that: “Animals are

not interacted with or, where there is interaction, it would not be expected to

compromise the animal’s welfare any more than normal handling, feeding etc.

There is no pain, suffering or discomfort involved.”

YES

If the answer to 4 is “no” go to:

question 5 for work with wild or domestic animals

question 6 for work with laboratory animals.

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5. Studies involving wild or domestic animals: Do you or your supervisor believe

there are special ethical issues with the proposed study that you would like

reviewed by the ethics committee?

NO

If yes, what are they?

6. Studies involving laboratory animals: Can you confirm that the work is covered

by a project license under the animals scientific procedures act 1986?

YES

If yes, please specify which procedures require a project license?

Variation in the composition, constituents, quantity and/or availability of the diet

and/or drinking water which may cause pain, suffering, distress or lasting harm.

If yes, can you confirm that an individual who holds a personal license

under the animals scientific procedures act 1986 will be carrying out these

procedures for you?

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YES

IF YOUR STUDY INVOLVES BOTH HUMANS AND ANIMALS (for example , you

are monitoring human responses to animal behaviour) you must also complete the

ethics form for research with human participants, which is available at:

http://www.sussex.ac.uk/psychology/1-3-14.html

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DEPARTMENT OF PSYCHOLOGY

ETHICS FORM FOR RESEARCH WITH ANIMALS PART B

Summary sheet for projects: Please complete each section.

Title:

Give your project a title, even though you may decide to change it later

The Effect of Reconsolidation on Contextual Extinction.

Investigators:

Your name

Kate Doran

Your email address

[email protected]

Supervisor

Hans Crombag

Background (no more than 150 words):

Explain the aims of your project, and refer very briefly to relevant previous research.

Provide a rationale for your research, and explain what contribution it is likely to

make. State your hypotheses, with an appropriate justification.

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The aim of the experiment is to establish the extent to which reconsolidation can be

used to enhance extinction of a behaviour in multiple contexts. Research (Crombag &

Shaham, 2002; Crombag, Grimm, & Shaham, 2002; Bossert, Liu, Lu, & Shaham, 2004) has

shown that when re-exposed to a drug-associated context, rats reengage in drug-seeking

behaviour for a wide array of drugs. However, in regards to drug-taking context, this

suggests that any behavioural extinction that occurs in the rehabilitation clinic will only be

relevant to that context leaving the original drug-taking behaviour unaffected in previous

drug-taking contexts (Rescorla, 2001), or even a novel context (Gunther, Denniston, &

Miller, 1998).

Recent research (Monfils, Cowansage, Klann, & LeDoux, 2009) has suggested that

using reconsolidation prior to an extinction trial (within 6 hours after the isolated retrieval

trial [Nader, Schafe, & LeDoux, 2000]) enhances extinction so that the behaviour is

permanently altered (contrasting with standard extinction which leaves the original memory

unmodified [Pavlov, 1927]). If this finding can be applied to drug rehabilitation contexts, this

enhanced extinction could be used to reduce relapse when addicts return the old drug-

taking context (Childress, Hole, Ehrman, Robbins, McLellan, & O’Brien, 1993) or a novel

context. Currently, reconsolidation research has investigated areas such as fear (Monfils,

Cowansage, Klann, & LeDoux, 2009; Nader, 2003) and taste aversion (Eisenberg, Kobilo,

Berman, & Dubai, 2003) but, to our knowledge, an appetitive study has yet to be conducted.

A study into natural rewards (such as food) could enhance understanding and application of

findings to non-natural rewards (for example addictive drugs.) (Kelley & Berridge, 2002).

Based on previous research (Monfils, Cowansage, Klann, & LeDoux, 2009; See Crombag,

Bossert, Koya, & Shaham, 2008 for review) we hypothesise that those mice experiencing an

isolated retrieval trial and then receiving the extinction session will re-evaluate the value of

the CS leading to increased extinction being displayed in the previous conditioning setting.

Method summary: a) Describe your study population/subjects and study site/housing conditions.

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The animals used in this study would be 16 Mus musculus, mice. They would be maintained

on a normal 24hour cycle consisting of 12 hours light and darkness; experiments occurred in

the day portion of the cycle. In hours outside of experimentation the animals would be

housed in groups of 2-4 littermates. The animals would be food deprived throughout the

study; their weight being maintained at 90% of their initial body weight. Animals would

have access to water was ad libitum for the throughout the experiment.

b) What is your design?

The design of the experiment is a 2-way between –within measures design.

c) Give a description of any materials.

During the experimental portion the mice will be trained in 3 discrminably different contexts

(skinner boxes). The three different contexts would be provided by three sets of operant

chambers. In the following aspects these boxes would be the same: each Skinner box would

be constructed of unpainted metal walls and measuring 27 x 25.8 x 30.4 cm in length, width,

and height.

The boxes from context A, B and C will differ in terms of their tactile, visual and olfactory

background stimuli. The skinner boxes used for context A would be scented with vinegar,

the lighting would be altered using red acetate. The floor of each skinner box would be lined

with woodchips. Conversely, in context B the boxes would be scented using “vapour rub”,

the bulb would be left uncovered and the grids of the skinner box would also be left

uncovered.

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The Skinner boxes from Context C will be scented using essential oils, the light will be

coloured using green acetate and the floor of the Skinner box will be lined with a plastic

sheet. In order to further differentiate the environments the mice will be placed in each

context at different times of the day. Context A exposure will be in the morning, context B

around Noon and Context C in the afternoon.

These contexts will be referred to as A, B and C with A being the context in which training

and self-administration of sucrose took place, B as the extinction and C as the

alternative/testing context.

20% (w/v) sucrose solution made fresh daily

Eight mice per experimental group

A computer running (insert details of programs here) and interfaced with the conditioning

chambers

Conditioning chambers

Plastic syringes and hypodermic needles

Retractable levers

Liquid delivery receptacle

Auditory stimulus modules to present CS tone

Light stimulus to present alternative CS tone

Decibel (dB) meter for calibration of auditory stimuli (10 dB above background)

d) Provide a brief description of the procedure you will use.

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Firstly, the mice would engage in a brief (20 minutes for 2 days) period of receptacle

approach training. This involves the mice being placed in a training context [context A] with

a syringe pump which is activated on a RI30 schedule [min=15seconds, max=45seconds]

which is set to deliver a small volume of sucrose solution [approximately 50µl] into the

receptacle cup.

For the next eleven days the Mice would be placed in Context A and receive 20

conditioning trials to which a cue light (this would be counterbalanced with an auditory tone

for half of the mice) was paired with 10% sucrose delivery (CS+) and 20 trials in which an

auditory cue (again this would be counterbalanced using a light cue for half of the mice)

was presented with no sucrose delivered (CS-). Cues would be presented in 10second

durations. Throughout these (CS+) trials, 50µl sucrose solution was infused into the food-

cup receptacle 5 second succeeding cue onset.

The population of mice will be halved on day 16. These groups would both take part

in a retrieval trial in Context B. The first group, RET10min, would then be returned to their

homes cages for 10minutes before the 60 minute extinction session in Context B was

initiated. Following ach lever press of the right lever (counterbalanced for half of the mice)

the CS+ was presented in the absence of any sucrose solution being delivered. The second

group, RET6hr, will undergo the retrieval trial and then be returned to their homes cages for

6 hours before they take part in the 60 minute extinction session.

The mice will then be returned to their home cages and 24 hours later all mice would

be tested for extinction in Context C (allowed to lever press in Context A) in short 20 minute

trials.

e) Include a statement on ethical issues. – Even if there are none, you need to demonstrate

that you have thought about this, and justify your conclusion that there are no issues.

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Variation in the composition, constituents, quantity and/or availability of the diet and/or

drinking water which may cause pain, suffering, distress or lasting harm.

The justification for the use of animals in this study is the extensive research into appetitive

behaviour using classical or Pavlovian conditioning that has already taken place.. The effect

of context within this framework has also been researched at length. This provides a

invaluable baseline for comparison, which simply does not exist for human participants,

allowing us to examine the full effect of a relatively new methodology.

An ethical issue, concerned with our study, will be the stress induced due to our procedure.

This stress will be caused by two factors. Firstly, the mice will be stressed due to handling

the animals when transferring them from their housing to the conditioning and testing

contexts. Secondly in some mouse strains or in mice with genetic mutations limiting food

can be poorly tolerated. Therefore, it will very important to monitor the health of the

animals carefully throughout the period of food restriction particularly during the first few

days. Mice are also known to show a level of neophobia when exposed to novel food (Amico

et al., 2005). Therefore, to reduce this it would be beneficial to expose the animals to the

reinforcer initially in their home environment.

f) Indicate briefly how you will analyse your data.

A between-Within subjects (independent measures) two-tailed t-test and a within subjects

two-tailed t-test will be used to analyse the data.

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