Fear conditioning…

e.g., Electric shock associated with specific stimuli

SCR: Skin Conductance Response (sweat)

Fear-relevant: e.g., snakeFear-irrelevant: e.g., butterfly

SCR: Skin Conductance Response (sweat)

Fear-relevant: e.g., snakeFear-irrelevant: e.g., butterfly

SCR: Skin Conductance Response (sweat)

SCR: Skin Conductance Response (sweat)

SCR: Skin Conductance Response (sweat)

Same RaceDifferent Race

• Operant Conditioning: learning when an individual’s response is followed by a reinforcement or punishment

– Reinforcement: an event that increases the future probability of the response that produced it•Positive reinforcement: Reward •Negative reinforcement: Escape from

punishment

– Punishment: an event that suppresses the future probability of the response that produced it

Operant conditioning

Biological needs

Several hours have passed since last meal

Find food, eat it

Drive is reduced (reinforcement)

The drive reduction hypothesis

Increased drive (hunger)

Increased exploratory activity

Biological needs

Several hours have passed since last meal

Increased drive (hunger)

Increased exploratory activity

Find food, eat it

Drive is reduced (reinforcement)

The drive reduction hypothesis

For instance, rats learning to work for food

Skinner Box

For instance, rats learning to work for food

Response to central hole= a way to obtain food

Phase One

A new experiment…

Response to central hole= a way to obtain food

Phase One

A new experiment…

Better deal to the right> Will rats figure it out?

Phase Two

Better deal to the right> Will rats figure it out?

Better deal to the right> Will rats figure it out?

Yes, in a couple of days

Concurrent changes in neural functioning

• growth of new neurons• growth of new synapses• increase or decrease in transmitter release• increase or decrease in sensitivity to

transmitter releasechanges in concentration of receptors

Long Term Potentiation

  • The most widely studied neuroplastic phenomena

of the mammalian nervous system

• Considered a fundamental mechanism underlying learning and memory in mammals.

What is Long Term Potentiation?

Enduring facilitation of synaptic transmissionfollowing activation of a synapse by intense high-

frequencystimulation of pre-synaptic neurons…

or

Changes in the postsynaptic neuron resulting in the strengthening of synaptic transmission.

The key event is the co-occurrence of the pre and post synaptic neurons.

Neurons that fire together wire together

while

neurons that are out of sync lose their link.

Most commonly studied in neurons from the hippocampus

Biochemical Mechanisms of LTP in Hippocampus

• AMPA and NMDA receptors are involved in LTP– glutamate receptors that open channels in

postsynaptic neurons to let in one or more kinds of ions (ionotropic)

• AMPA receptors: glutamate opens sodium channels

• NMDA receptors: normally blocked by magnesium but respond to glutamate when the neuron is depolarized by AMPA receptors– calcium enters and activates protein CaMKII, which is

necessary for LTP, and sets several processes in motion:•structure of AMPA receptors change, becoming more

responsive to glutamate•some NMDA receptors change to AMPA receptors and

increase their responsiveness to glutamate•dendrites may build more AMPA receptors and make

more branches

• Once established, LTP no longer depends on NMDA synapses

LTP and Behavior

• Research shows

– abnormal NMDA receptors impair learning – more than normal NMDA receptors enhances

learning– drugs that block LTP block learning while

drugs that facilitate LTP facilitate learning– a lack of AMPA receptors creates deficits in

LTP and memory

Types of memory

• Declarative memory – Facts (who is…, what is…)– Events (when did you…)

• Non-declarative memory– Procedures (how do you…)– Conditioning (automatic responses)

•Musculature •Emotional

• Declarative memory – Facts (who is…, what is…)– Events (when did you…)

• Non-declarative memory– Procedures (how do you…)– Conditioning (automatic responses)

•Musculature •Emotional

Medial temporal lobe

Hippocampus

Types of memory

• Declarative memory – Facts (who is…, what is…)– Events (when did you…)

• Non-declarative memory– Procedures (how do you…)– Conditioning (automatic responses)

•Musculature •Emotional

Medial temporal lobe

Hippocampus

Striatum

Cerebellum

Amygdala

Types of memory

More types of memory…

• Long-term memory– Questions about encoding, retrieving– Medial temporal lobe (“store”)

• Short-term memory– Working memory– (Consciousness, attention) – Dorsolateral frontal cortex (“operator”)