Functional magnetic resonance imaging of human brain activity in a verbal fluency task

Abstract

Objectives-Functional MRI (fMRI) holds the promise of non-invasive mapping of human brain function in both health and disease. Yet its sensitivity and reliability for mapping higher cognitive function are still being determined. Using verbal fluency as a task, the objective was to ascertain the consistency of fMRI on a conventional scanner for determining the anatomic substrate of language between subjects and between sexes. Comparison was made with previous PET studies. Methods-Using a 1.5 Tesla magnet and an echoplanar pulse sequence, whole brain fMRI was obtained from 12 normal right handed subjects (6 males and 6 females) as they performed a verbal fluency task. However, decremental responses were seen over a much larger area of the posterior cortex than had been anticipated by prior studies. The ability to see a response in each subject individually suggests that fMRI may be useful in the preinterventional mapping of pathological states, and oVers a non-invasive alternative to the Wada test for assessment of hemispheric dominance. There were no gross diVerences in the pattern of activation between male and female subjects. (J Neurol Neurosurg Psychiatry 1998;64:492-498)

Epistasis between the DAT 3′ UTR VNTR and the COMT Val158Met SNP on cortical function in healthy subjects and patients with schizophrenia

“…The supramarginal gyrus is thought to be involved in the integration of somatosensory, auditory, and visual input (61), and in the phonological and articulatory processing of words (62). It has consistently been engaged in previous studies of verbal fluency (47,50,53,63,64); it also has a role in semantic representation (65) and in decision making under conditions of uncertainty (66). In this area, subjects with the Met-158/Met-158 COMT genotype who carried the 9-repeat DAT allele showed more activation than Met-158/Met-158 subjects who carried 2 copies of the 10-repeat allele.…”

“…In patients, both the Val-158-9-repeat combination and the Met-158-10-repeat combination were associated with higher activation, whereas in healthy subjects, there was a trend in the opposite direction. Although its reports of association with verbal fluency and differential activation in schizophrenia have not been as frequent as those in the adjacent inferior frontal gyrus (46,47,50,51,53,63,64), the right orbitofrontal cortex has shown abnormal volume in schizophrenic patients (71)(72)(73)(74)(75) and significant activation during verbal fluency in females (50); it has also been linked to semantic processing (76,77). An interaction between diagnostic group and genetic variations that influence dopamine transmission in the orbitofrontal cortex is also consistent with the presence of dopaminergic inputs to the prefrontal cortex, and with the putative disruption of dopaminergic inputs to prefrontal cortex in schizophrenia (36)(37)(38)(39)(40).…”

“…We used 2 well-characterized functional polymorphisms (COMT Val158Met and DAT 3Ј UTR VNTR) and functional MRI to study healthy volunteers and patients with schizophrenia, with genotype subgroups of sufficient size to detect interactive effects of both genes on activation by using an ANOVA. Subjects were scanned while they performed an overt phonological verbal fluency paradigm, which is associated with activation in the frontal, cingulate, and temporal cortex in healthy volunteers (46)(47)(48)(49)(50)(51)(52)(53)(54), and with impaired performance (55,56) and altered activation (51,54,(57)(58)(59)(60) in schizophrenia. On the basis of evidence that variation in DAT (at the 3Ј UTR VNTR) and in COMT (at the Val158Met SNP) separately modulate fronto-temporal activation during verbal fluency, and that these effects are altered in patients with schizophrenia (27, 84), we predicted that there would be an epistatic interaction between their effects on regional activation in the same sample and paradigm.…”

Which Executive Functioning Deficits Are Associated With AD/HD, ODD/CD and Comorbid AD/HD+ODD/CD?

“…Verbal fluency tends to be associated in particular with functioning of the left prefrontal cortex (for review, see Cohen, Morgan, Vaughn, Riccio, & Hall, 1999; also see Frith, Friston, Liddle, & Frackowiak, 1991;Gaillard et al, 2000;Parks et al, 1988;Phelps, Hyder, Blamire, & Shulman, 1997;Pujol et al, 1996;Schlosser et al, 1998).…”

Handedness Shift as a Consequence of Motor Cortex Reorganization After Early Functional Impairment in Left Temporal Lobe Epilepsy—An fMRI Case Report

“…The Wada procedure could not be completed due to an unexpected arterial spasm; fMRI was used to determine the hemispheric speech dominance. A silent phonemic verbal fluency task (VFT) was used as a language paradigm (Schlosser et al, 1998). We then evaluated the direction and degree of cerebral lateralization of motor function using fMRI.…”