Journal of the International Neuropsychological Society



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Role of frontal versus temporal cortex in verbal fluency as revealed by voxel-based lesion symptom mapping


JULIANA V.  BALDO  a1 c1 , SOPHIE  SCHWARTZ  a2 , DAVID  WILKINS  a1 and NINA F.  DRONKERS  a1 a3 a4
a1 Center for Aphasia and Related Disorders, VA Northern California Health Care System, Martinez, California
a2 Departments of Neuroscience and Clinical Neurology, University of Geneva, Switzerland, Geneva, Switzerland
a3 Department of Neurology, University of California, Davis, Davis, California
a4 Center for Research in Language, University of California, San Diego, San Diego, California

Article author query
baldo jv   [PubMed][Google Scholar] 
schwartz s   [PubMed][Google Scholar] 
wilkins d   [PubMed][Google Scholar] 
dronkers nf   [PubMed][Google Scholar] 

Abstract

Category and letter fluency tasks have been used to demonstrate psychological and neurological dissociations between semantic and phonological aspects of word retrieval. Some previous neuroimaging and lesion studies have suggested that category fluency (semantic-based word retrieval) is mediated primarily by temporal cortex, while letter fluency (letter-based word retrieval) is mediated primarily by frontal cortex. Other studies have suggested that both letter and category fluency are mediated by frontal cortex. We tested these hypotheses using voxel-based lesion symptom mapping (VLSM) in a group of 48 left-hemisphere stroke patients. VLSM maps revealed that category and letter fluency deficits correlate with lesions in temporal and frontal cortices, respectively. Other regions, including parietal cortex, were significantly implicated in both tasks. Our findings are therefore consistent with the hypothesis that temporal cortex subserves word retrieval constrained by semantics, whereas frontal regions are more critical for strategic word retrieval constrained by phonology. (JINS, 2006, 12, 896–900.)

(Received March 28 2006)
(Revised June 21 2006)
(Accepted June 21 2006)


Key Words: Fluency; Lexical retrieval; Letter fluency; Category fluency; Temporal cortex; Frontal cortex; Semantic retrieval.

Correspondence:
c1 Correspondence and reprint requests to: Juliana Baldo, 150 Muir Road (126s), Martinez, CA 94553, USA. E-mail: juliana@ebire.org