Task and semantic relationship influence both the polarity and localization of hemodynamic modulation during lexico-semantic processing.

Full Abstract

This study examined how task (implicit vs. explicit) and semantic relationship (direct vs. indirect) modulated hemodynamic activity during lexico-semantic processing. Participants viewed directly related, indirectly related, and unrelated prime-target word-pairs as they performed (a) an implicit lexical decision (LD) task in which they decided whether each target was a real word or a nonword, and (b) an explicit relatedness judgment (RJ) task in which they determined whether each word-pair was related or unrelated in meaning. Task influenced both the polarity and neuroanatomical localization of hemodynamic modulation. Semantic relationship influenced the neuroanatomical localization of hemodynamic modulation. The implicit LD task was primarily associated with inferior prefrontal and ventral inferior temporal/fusiform hemodynamic response suppression to directly related (relative to unrelated) word-pairs, and with more widespread temporal-occipital response suppression to indirectly related (relative to unrelated) word-pairs. In contrast, the explicit RJ task was primarily associated with left inferior parietal hemodynamic response enhancement to both directly and indirectly related (relative to unrelated) word-pairs, as well as with additional left inferior prefrontal hemodynamic response enhancement to indirectly related (relative to unrelated) word-pairs. These findings are discussed in relation to the specific neurocognitive processes thought to underlie implicit and explicit semantic processes. Hum Brain Mapp, 2008. (c) 2007 Wiley-Liss, Inc.(Copyright) 2006 Wiley-Liss, Inc.

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Author information

Author/s: Kuperberg, Gina R (GR); Lakshmanan, Balaji M (BM); Greve, Douglas N (DN); West, W Caroline (WC);

Affiliation: Department of Psychology, Tufts University, Medford, MA 02155, USA. kuperber(-atsign-)nmr.mgh.harvard.edu

Grants: K01 MH65356 (Agency:United States NIMH) ; R01 MH071635 (Agency:United States NIMH)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: Human brain mapping (Hum Brain Mapp), published in United States. (Language: eng)

Reference: 2008-May; vol 29 (issue 5) : pp 544-61

Dates: Created 2008/04/17; Completed 2008/07/22;

PMID: 17674356, status: MEDLINE (last retrieval date: 11/6/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Brain - blood supply; physiology
Brain Mapping
Cerebrovascular Circulation - physiology
Female
Hemodynamics

Humans
Language
Magnetic Resonance Imaging
Male
Paired-Associate Learning - physiology
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