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Priming, Implicit Memory, and the Brain: A Neuroimaging Perspective Daniel L. Schacter Harvard University.

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Presentation on theme: "Priming, Implicit Memory, and the Brain: A Neuroimaging Perspective Daniel L. Schacter Harvard University."— Presentation transcript:

1 Priming, Implicit Memory, and the Brain: A Neuroimaging Perspective Daniel L. Schacter Harvard University

2 Acknowledgements Memory Lab, Harvard Psychology Donna Addis Elissa Aminoff Elizabeth Chua Rachel Garoff-Eaton Angela Gutchess Dale Stevens Gagan Wig Alana Wong Athinoula A. Martinos Center for Biomedical Imaging Supported by NIMH and NIA

3 MYSTERY

4 APRICOT

5 CUPCAKE

6 ASSASSIN

7 _ _ES_ _X

8 _UP_ _KE

9 Tulving, Schacter, & Stark (1982)

10

11

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13 Picture Fragment ID after 17 Years (M Age = 39.2; Mitchell, 2006)

14 Some Properties of Priming on Stem Completion, Fragment Completion and Identification Tests * Unaffected or even reduced by semantic or elaborative encoding manipulations that enhance recall and recognition. *Sensitive to changes between study and test in the physical features of target items: sensory modality, word font, case. Such changes typically have smaller effects on recall and recognition. *Typically preserved in amnesic patients with impairments on recall and reocgnition tests.

15 Characterizing Dissociations: Memory Systems Priming on tests such as completion and identification is little affected by semantic processing and highly dependent on physical features of stimuli. Led to postulation of perceptual representation system (‘PRS’): involves storage/retrieval of modality- specific information that supports identification of words/objects (Schacter, 1990;Tulving & Schacter, 1990). “Pre-semantic” collection of susbsystems (visual word form, auditory word form, structural description) that depend on posterior cortical brain regions, not hippocampus/MTL; should be preserved in amnesia.

16 Object Priming Paradigm STUDYTEST 2 SEC BETWEEN STIMULI

17 Behavioral Performance at Test NOVEL REPEATED REACTION TIME (MSEC) ++

18 Novel > Repeated Same Left anterior inferior frontal cortex (BA 47, 45) Bilateral fusiform, extending into parahippocampal cortex (BA 37, 19) Reduced activation (indicating priming) for repeated objects in multiple regions, including: Priming-related activation decreases

19 Specificity of Priming-Related Reductions Neural correlates of priming for: Novel objects Repeated same objects Repeated different objects 18 subjects scanned while undertaking size judgements of visually- presented objects. Koutstaal et al. (2001) Neuropsychologia

20 Fusiform Laterality Effect Repeated Different > Repeated Same Bilateral fusiform (BA 37, 19). Greater effect of exemplar change in Right than Left fusiform cortex Greater activation (indicating less priming for Different) in:

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22 Explaining Activation Decrease in Object Priming Wiggs, C. L., & Martin, A. (1998). Properties and mechanisms of perceptual priming. Current Opinion in Neurobiology. “Neural Tuning”

23 High PrimeNovel “Bigger than a shoebox? (yes/no)” 1.Start Phase 2.Switch Phase “Smaller than a shoebox? (yes/no)” High PrimeNovel Low PrimedHigh Primed 3.Return Phase “Bigger than a shoebox? (yes/no)” Low PrimedNovelHigh Primed Low PrimeNovel Low Prime n = 16, Event Related, 4 - Cycles Is Object Priming Response Specific? Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

24 Cue Reversal - fMRI Novel Low High StartSwitchReturn Mean Reaction Time - milliseconds a Is Object Priming Response Specific? Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

25 -15 StartSwitch Return Mean “Neural Priming” PFC Fusiform Is Object Priming Response Specific? PFC Fusiform StartSwitchReturn Forgetting Control Dobbins, Schnyer, Verfaellie & Schacter (2004) Nature

26 Is Object Priming Response Specific? Relation to Behavior -15 Both fusiform and PFC “neural priming” scores predicted behavioral priming scores, each accounting for unique variance. PFC (not fusiform) neural priming predicted size of behavioral slowing that occurred when cue was switched…suggests that lack of activity is a marker of automaticity.

27 Frontal Temporal Perceptual -Dobbins et al. (2004) -Maccotta & Buckner (2004) -Lustig & Buckner (2004) -Bergerbest et al. (2005) -Golby et al. (2005) -Oranfidou et al. (2006) -Bunzeck et al. (2006) -Turk-Browne et al. (2006) -Carlesimo et al. (2003) Is there a correlation between behavioral & neural priming? -Dobbins et al. (2004) -Turk-Browne et al. (2006)

28 A Stimulus Specificity Most Least LR Schacter, Wig & Stevens (2007). Curr Opin Neurobiol A multiple component model of priming

29 A D A Stimulus Specificity Most Least LR Schacter, Wig & Stevens (2007). Curr Opin Neurobiol A multiple component model of priming -Amodal -Priming across abstract representations -Sensitive to changes in stimulus-decision mapping

30 A D A Stimulus Specificity Most Least LR Schacter, Wig & Stevens (2007). Curr Opin Neurobiol A multiple component model of priming -Amodal -Priming across abstract representations -Sensitive to changes in stimulus-decision mapping -Most consistently correlated with behavior

31 Study Phase  For each of 3 runs at study, 144 shapes were presented (16 sets of 9 exemplars)  Each set alternated in spatial position to the right or left of fixation  Pres. Time = 2.5 sec  Instructions: remember each shape and side of the screen Nonstudied Prototype Exemplar Slotnick Schacter (2004) Nature Neuroscience

32 True recognition > False recognition Old-hits > Related-false alarms Related-false alarms > Old-hits Ventral View LH Early visual regions (BA17, BA18) Time (sec) % Signal change Left fusiform gyrus (BA18) Old-hits Related-false alarms X

33 LH Old-hits > Old-misses Old-hits + Old-misses Nature of visual area activity? * Old-hits > Old-misses should reflect conscious recollection Time (sec) % Signal change Left fusiform gyrus (BA37) Old-hits Old-misses New-correct rejections Late visual regions (BA19, BA37) * Old-hits + Old-misses expected to reflect nonconscious activity Time (sec) % Signal change Left cuneus (BA18) 0.4 Early visual regions (BA17, BA18) Ventral View

34 Line Orientation Task *For each shape (at ‘study’ or ‘test’), speeded response whether internal lines sloped: 1) upward 2) downward *Subjects were not informed that any shapes would be repeated.

35 Line Judgment Task: Old>Related Ventral View * Early visual regions (BA17, BA18) Old > Related Related > Old X LH Left lingual gyrus (BA18) Time (sec) % Signal change Old Related 0.2 * No late visual region activity (BA19,BA37) Slotnick & Schacter (2006) Neuropsychologia

36 Line Judgment Task: Behavioral Results OldRelated New Reaction Time (ms) ns * p < 0.05 * * Slotnick & Schacter (2006) Neuropsychologia

37 A D A Stimulus Specificity Most Least LR Schacter, Wig & Stevens (2007). Curr Opin Neurobiol A multiple component model of priming -Amodal -Priming across abstract representations -Sensitive to changes in stimulus-decision mapping -Most consistently correlated with behavior


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