˜e neural correlates of temporal and semantic clustering...

�e neural correlates of temporal and semantic clustering during retrievalNicole M. Long, Michael J. Kahana

Introduction

Methods

Behavioral results

EEG Oscillatory Power

References

CHAIR CATDOGAPPLE COAT DESK

“CHAIR” “CAT”“COAT” “DOG”“APPLE”“DESK”

study

recall

high semanticlow temporal

low semantichigh temporal

high semantichigh temporal

low semanticlow temporal

Bous�eld, WA (1953) �e occurrence of clustering in the recall of randomly arranged associates. J. Gen. Psych 49: 229-240Kahana, MJ (1996) Associative retrieval processes in free recall. Memory & Cognition 24: 103-109Nelson, DL & McEvoy, CL (2004) �e University of South Florida free association, rhyme and word fragment norms. Beh. Res. Methods 36 (3): 402-407Tulving, E (1962) Subjective organization in free recall of “unrelated” words. Psych Review 69 (4): 344-354�ompson, CP (1972) Organization in memory: Multitrial free recall of categorized word lists. In RF �ompson & JF Voss (Eds.), Topics in learning and performance (pp. 241-263). San Diego, CA: Academic Press

Free recall task where words vary in temporal and semantic relatednessTemporal relatedness determined by lag (di�erence in serial position) High temporal: lag = 1, Low temporal: lag > 2Semantic relatedness determined by word association score (Nelson et al., 2004)

High semantic: WAS > .4, Low semantic: WAS < .4

Organizational processes correlate with successful recall (Tulving, 1962; �ompson, 1972)

Temporal clustering: consecutive recall of nearby study items (Kahana, 2006)

Semantic clustering: consecutive recall of items related in meaning (Bous�eld, 1953)

How do neural mechanisms of temporal and semantic

clustering relate to those associated with recall success?

What mechanisms are shared/di�erent between temporal and semantic

clustering?

Prob

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Sem

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Semantic clustering Temporal clusteringTemporal clustering

Summary

EEG Methods: 102 participants | 7 sessions | 16 lists per session | 16 words per list | Scalp EEG, 129 electrodes

Prob

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f rec

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- Encoding and retrieval mechanisms di�er across all three measurementsRecalled - failure to recall- Encoding: power decreases across frequencies- Retrieval: greater low and high frequency power prior to vocalizationHigh - low temporal clustering- Encoding: theta power decreases, alpha power increases- Retrieval: early power increases; pre-vocalization power decreasesHigh - low semantic clustering- Encoding: low frequency power decreases- Retrieval: early power increases; pre-vocalization power decreases which begin earlier than temporal

Probability of recall positively correlated with temporal clustering

Temporal and semantic clustering are negatively correlated

Recalled - failure to recall

High - Low Temporal Clustering

High - Low Semantic Clustering

EncodingLe� Right

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RetrievalLe� Right

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Retrieval dynamics

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Recall

Power increasesPower decreases

�etaGamma

Temporal clustering Semantic clustering

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Is

Time from word onset (ms)

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EncodingLe� Right

RetrievalLe� Right

EncodingLe� Right

RetrievalLe� Right

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Freq

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Delta Z-power-.1 .10-.05 .05

Anterior SuperiorAnterior Inferior

Posterior Inferior

Time preceding vocalization (ms)

Time from word onset (ms) Time preceding vocalization (ms)

Time from word onset (ms) Time preceding vocalization (ms)0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.90.54

0.56

0.58

0.6

0.62

0.64

0.66

0.68

0.54 0.56 0.58 0.6 0.62 0.64 0.66 0.68

0.4

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0.9

1

0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

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1

R =.39P < .01

R =.15P = .12

R = -.27P < .01

Time preceding vocalization (ms)