Unmasking Language Lateralization in Human Brain Intrinsic Activity

Mark McAvoy, Anish Mitra, Rebecca S. Coalson, Giovanni D'Avossa, James L. Keidel, Steven E. Petersen, Marcus E. Raichle

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Lateralization of function is a fundamental feature of the human brain as exemplified by the left hemisphere dominance of language. Despite the prominence of lateralization in the lesion, split-brain and task-based fMRI literature, surprisingly little asymmetry has been revealed in the increasingly popular functional imaging studies of spontaneous fluctuations in the fMRI BOLD signal (so-called resting-state fMRI). Here, we show the global signal, an often discarded component of the BOLD signal in resting-state studies, reveals a leftward asymmetry that maps onto regions preferential for semantic processing in left frontal and temporal cortex and the right cerebellum and a rightward asymmetry that maps onto putative attention-related regions in right frontal, temporoparietal, and parietal cortex. Hemispheric asymmetries in the global signal resulted from amplitude modulation of the spontaneous fluctuations. To confirm these findings obtained from normal, healthy, right-handed subjects in the resting-state, we had them perform 2 semantic processing tasks: synonym and numerical magnitude judgment and sentence comprehension. In addition to establishing a new technique for studying lateralization through functional imaging of the resting-state, our findings shed new light on the physiology of the global brain signal.

Original languageEnglish
Pages (from-to)1733-1746
Number of pages14
JournalCerebral Cortex
Volume26
Issue number4
DOIs
StatePublished - Apr 1 2016

Keywords

  • attention network
  • global signal
  • hemispheric asymmetry
  • resting-state
  • semantic network

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