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Prospective memory: encoding and retrieval. Sam Gilbert Institute of Cognitive Neuroscience. Background. Prospective memory (PM) refers to our ability to encode intentions for future behaviour, then act on those intentions at the appropriate time
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Prospective memory: encoding and retrieval Sam Gilbert Institute of Cognitive Neuroscience
Background • Prospective memory (PM) refers to our ability to encode intentions for future behaviour, then act on those intentions at the appropriate time • Several recent fMRI studies have investigated brain mechanisms supporting this ability (Benoit et al., in prep; Burgess et al., 2001, 2003; Gilbert et al., in press; Okuda et al., 1998, 2007; Reynolds et al., in press; Simons et al., 2006) • These studies have all investigated retrieval of delayed intentions. The present study will look at encoding as well
Previous studies • Typically, participants are engaged in an “ongoing task”, e.g. making a button-press response to a series of words to indicate whether they have 4 or 6 letters • PM conditions: continue performing the ongoing task, but press a different button if you see an animal word PM > ongoing only ongoing only > PM Burgess et al., 2001 Burgess et al., 2003
Design Ongoing task: 2-back SONG PM encode REST SONG yes PM store (1 – 5 trials) WEAR no REST no PM retrieve: press different key WEAR yes SWIM no Control: PM encode CASE no Control: PM store (1 – 5 trials) NOTE no SWIM no Control: PM retrieve
Analyses • PM storage trials versus control: expect signal change in BA 10 • PM encoding versus control: same regions as involved in retrieval? • Subsequent prospective memory effect: encoding-related activity that distinguishes subsequent hits from misses? • Each PM cue will appear twice in the experiment. Half of blocks use words, half pictures. Multi-voxel pattern analysis to find out whether the intention can be decoded from storage trials (specific intention / word versus picture) Methods • Standard EPI imaging parameters: 3mm x 3mm x 3mm voxels, 33 slices, TR=2.5s • 3s per trial; 7 trials per ‘miniblock’ (i.e. PM or control), total: 48 PM, 48 control trials • 6 runs of approx 6 minutes + 6 minute structural scan: total scanner time = 42 mins • Analysis in SPM5