prospective memory: encoding and retrieval
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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
SONG
REST
SONG
WEAR
REST
WEAR
SWIM
CASE
NOTE
Ongoing task: 2-back
yes
no
no
yes
no
no
no
PM encode
PM store (1 – 5 trials)
PM retrieve: press different key
SWIM no
Control: PM encode
Control: PM store (1 – 5 trials)
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
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