DIFFERENTIAL COMPONENTS OF PROSPECTIVE MEMORY? EVIDENCE FROM FMRI

J. Simons, M. Scholvinck, S. Gilbert, C. Frith, P. Burgess

By Alex Gustafson

WHAT IS PROSPECTIVE MEMORY? Remembering to perform an action after a delay Event-based PM – 2 components:

Cue identification Intention retrieval

BEHAVIOURAL VS. COGNITIVE DIFFERENCES Behaviour:

Cue identification is stimulus driven Intention retrieval is conceptually driven

Do the two different behaviours rely on the same brain areas? The anterior prefrontal cortex (Brodmann area 10) is activated

during PM tasks Cue identification and intention retrieval have not been previously

separated experimentally to test activation It is expected that the anterior prefrontal network supports PM

function regardless of the demands on each process

EXPERIMENT Subject-paced “Uncontaminate

d” trials (x2) “Contaminated”

trials (x4) Unrelated task X X X X Word and shape

tasks were used to determine activation based on PM

X XX

RESULTS Reaction Time

Uncontaminated < Contaminated ongoing trials Cue identification < Intention retrieval

Neuroimaging Consistent pattern of activation in:

Anterior prefrontal, ventrolateral prefrontal and lateral parietal cortex Lateral BA 10 activated Medial BA 10 deactivated Differential BA 10 involvement:

RESULTS Cue identification:

Medial BA 10 more activated Anterior cingulate

Intention retrieval: Lateral BA 10 more activated Dorsolateral prefrontal cortex and orbitofrontal cortex Cingulate gyri Precuneus

FMRI RESULTS

DISCUSSION BA 10 is of central importance to prospective memory

The experimental conditions were not exclusive, however behavioural effects were seen

Behavioural differences could not explain hemodynamic changes

DISCUSSION Lateral BA 10 activation increased due to attention to

internal representations of what must be retrieved from memory Context

Medial BA 10 involved in attention towards external events

Overall role of BA 10: A “gateway” between cognitive process needed to detect perceptual

information and derive intention

OPINION Introduction was well written; good background

Clear results Further correlational study helped to solidify findings

Huge amount of detail in the methods section

Tables may be useful if conducting a further study, but were not clearly interpreted

STRENGTHS AND LIMITATIONS

Strengths Limitations fMRI showed clear results

Easy to follow

Analyzed many aspects giving more comprehensive results yet stayed focused

Extensions from results were limited

Could not fully separate cue identification and intention retrieval conditions

FUTURE EXPERIMENTS Vary age of participants

All 16 subjects were 18-30 Differences in older people or people with PM loss?

Manipulate actions that require external and internal attention Do activities requiring reaction to external stimuli necessarily

depend on BA 10 as a gateway? Implicit memory task

SUMMARY BA 10 is central to PM functioning

Cue identification vs. intention retrieval behaviourally distinct share a common neural basis

Cue identification is largely dependent on external stimuli Higher medial BA 10 activation

Intention retrieval is more cognitively demanding Increased lateral BA 10 activation

QUESTIONS?