Human primary motor cortex shows hemispheric specialization for speech

Makoto Terumitsu, Yukihiko Fujii, Kiyotaka Suzuki, Ingrid Kwee, Tsutomu Nakada

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Hemispheric specialization is a prominent characteristic of the human brain. Should the 'dominant' hemisphere possess differential neural organization for language production in the 'higher order' cortex, it would be rational to consider that the primary motor cortex may also show similar hemispheric specialization for speech production. In order to test this hypothesis, we investigated the spatial distribution of neural activities associated with phonation (M1p), silent tongue motion (M1t), and vocalization (M1v) within the primary motor cortex, utilizing independent component-cross correlation- sequential epoch analysis of high-field functional magnetic resonance imaging time series. While M1t showed no significant differences between the two hemispheres, M1p and M1v exhibited significant hemispheric differences. The study demonstrated direct evidence that human primary motor cortex possesses clear-cut hemispheric specialization similar to that observed for the higher order cortices.

Original languageEnglish (US)
Pages (from-to)1091-1095
Number of pages5
Issue number11
StatePublished - Jul 2006


  • Functional magnetic resonance imaging
  • Hemispheric specialization
  • Independent component-cross correlation-sequential epoch analysis
  • Motor cortex
  • Speech

ASJC Scopus subject areas

  • Neuroscience(all)


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