Differential components of prospective memory? Evidence from fMRI

1. Differential components of prospective memory? Evidence from fMRI J. Simons, M. Scholvinck, S. Gilbert, C. Frith, P. Burgess By Alex Gustafson

2. What is prospective memory? • Remembering to perform an action after a delay • Event-based PM – 2 components: • Cue identification • Intention retrieval

3. 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

4. Experiment • Subject-paced • “Uncontaminated” trials (x2) • “Contaminated” trials (x4) • Unrelated task X XXX • Word and shape tasks were used to determine activation based on PM X X X

5. 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:

6. 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

7. fMRI Results

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. Questions?