Retrieval Success and the Prefrontal Cortex Evidence from fmri

Transcription

1 Retrieval Success and the Prefrontal Cortex Evidence from fmri Episodic Retrieval Pre-retrieval Retrieval Post-retrieval Michael Rugg Center for the Neurobiology of Learning and Memory UC Irvine processing recovery/ reinstatement of stored information monitoring & evaluation intentions, goals, etc Wellcome Trust Medical Research Council Item- & State-Related Effects Episodic Retrieval Item effect Item Pre-retrieval Retrieval Post-retrieval TASK ONSET State effect S1 S2 S3 S4 processing recovery/ reinstatement of stored information monitoring & evaluation State intentions, goals, etc Episodic Retrieval Prefrontal / Effects in Yes/No Recognition Memory identified by Event-Related fmri (as at 2001) Item State Pre-retrieval Retrieval Post-retrieval processing recovery/ reinstatement of stored information intentions, goals, etc monitoring & evaluation Konishi Donaldson Saykin Henson (b) Henson (a) Maratos McDermott Cabeza L Anterior (BA 9/10) L Dorsal L Ventral R Anterior R Dorsal R Ventral (BA 9/46) (BA45/47) (BA 9/10) (BA 9/46) (BA 45/47)

2 fmri Study of Remember/Know fmri Correlates of Remember/Know Study Lexical decision judgment on a series of words and nonwords Know & Remember > Know > Remember Test and words: Remember / Know / judgment Henson, J. Neurosci., 1999 Henson, J. Neurosci., 1999 Retrieval Success vs. Confidence Retrieval Success vs. Confidence LOW>HIGH CONF (regardless of old/new) LOW>HIGH CONF (regardless of old/new) OLD>NEW (regardless of confidence) z =24 z =24 z =21 z = -12 Henson, 2000 Henson, 2000 Recognition vs Source Memory Recognition vs Source Memory Main Effect > / x Task Interaction Main Effect > / x Task Interaction y = 50 y = 20 y = 50 y = Rugg, REC SOU REC SOU Rugg, REC SOU REC SOU 2

3 Prefrontal Cortex and Retrieval Success? Anterior PFC Sensitive to success per se representation and/or processing of retrieved information Study 75 words 75 words 75words (Right) Dorsolateral PFC Sensitive to degree of post-retrieval monitoring required after a retrieval attempt prior to response selection Test 25old:75new 50old:50new 75old:25new (Low) (Equal) (High) Other regions -? Main Effect of / z=39 z=21 L Ant Fron R Ant Fron R D lateral R D lateral L Inf Fron 3

4 1 2 3 L Ant Fron R Ant Fron Low R D lateral Equal 1.5 High 0.5 µv Low Equal High L Inf Fron ms + 5µV Conclusions Acknowledgements Multiple prefrontal regions sensitive to retrieval success (old vs new) They don t all do the same thing (e.g. dorsolateral vs. anterior) None of them appear to be involved directly in the representation or processing of retrieved information per se (at least during recognition) Seem to support processes contingent upon the outcome of a retrieval attempt. e.g. adjustment/maintenance of response criteria, retrieval strategy, or signalling the salience of the test item (c.f. oddball tasks) Rik Henson - Institute of Cognitive Neuroscience and Institute of Neurology, UCL Jane Herron - Department of Psychology, University of Cardiff William Robb - Institute of Cognitive Neuroscience, UCL Retrieval Success Effects in Blocked Designs Electrophysiological Correlates of Successful Source Memory High density /new recognition Low density LF RF Rugg, 1998 Le Page, 2000 LP RP 0 600ms 0 600ms + 5µV Source Correct Source Incorrect Wilding and Rugg, Brain,

5 Right frontal ERP Effect Without Recollection fmri Correlates of Recognition Exclusion Shallow Study Target > ms N O INC N T NT EXC Recognized Rugg et al, J.Cog Neurosci, 2000 Rugg, Neuropsychologia, Neural Correlates of Postretrieval Monitoring Prefrontal Cortex and Memory Retrieval Yes/No Recognition Is there a memory signal? Source What s the origin of the memory signal? Is the Prefrontal Cortex necessary for retrieval? Functional Dissociation do different regions of the PFC support different components of retrieval processing? Functional Characterization what are these components? Are any of these components unique to memory retrieval, or are they better conceived in terms of the recruitment of more general frontal processes? Source vs Recognition Memory Source vs Recognition Memory TEST Scheme Giraffe Inclusion vs Dentist Trellis Rugg, Rugg,

6 Source vs Recognition Memory Source vs Recognition Memory TEST Giraffe Target Inclusion TEST Giraffe Scheme vs Scheme Dentist Trellis Target Nontarget Exclusion Target vs Nontarget & Dentist Trellis Rugg,2003. Rugg,