"Willed action": A functional MRI study of the human prefrontal cortex during a sensorimotor task

Fahmeed Hyder, Elizabeth A. Phelps, Christopher J. Wiggins, Kevin S. Labar, Andrew M. Blamire, Robert G. Shulman

Research output: Contribution to journalArticle

Abstract

Functional MRI (fMRI) was used to examine human brain activity within the dorsolateral prefrontal cortex during a sensorimotor task that had been proposed to require selection between several responses, a cognitive concept termed "willed action" in a positron emission tomography (PET) study by Frith et al. [Frith, C. D., Friston, K., Liddle, P. F. & Frackowiak, R. S. J. (1991) Proc. R. Soc. London Ser. B 244, 241-246]. We repeated their sensorimotor task, in which the subject chooses to move either of two fingers after a stimulus, by fMRI experiments in a 2.1-T imaging spectrometer. Echo-planar images were acquired from four coro-nal slices in the prefrontal cortex from nine healthy subjects. Slices were 5 mm thick, centers separated by 7 mm, with nominal in-plane spatial resolution of 9.6 × 5.0 mm2 for mean data. Our mean results are in agreement with the PET results in that we saw similar bilateral activations. The present results are compared with our previously published fMRI study of a verbal fluency task, which had also been proposed by Frith et al. to elicit a "willed action" response. We find a clear separation of activation foci in the left dorsolateral prefrontal cortex for the sensorimotor (Brodmann area 46) and verbal fluency (Brodmann area 45) tasks. Hence, assigning a particular activated region to "willed action" is not supported by the fMRI data when examined closely because identical regions are not activated with different modalities. Similar modality linked activations can be observed in the original PET study but the greater resolution of the fMRI data makes the modality linkages more definite.

Original languageEnglish (US)
Pages (from-to)6989-6994
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume94
Issue number13
DOIs
StatePublished - Jun 24 1997

Keywords

  • Brodmann areas 6, 8, 9, 24, 32, 45, and 46
  • Dorsolateral prefrontal cortex
  • Human brain mapping
  • Positron emission tomography
  • Verbal fluency

ASJC Scopus subject areas

  • General

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