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

doi:10.1093/cercor/bhv007

Unmasking Language Lateralization in Human Brain Intrinsic Activity

Cereb Cortex. 2016 Apr;26(4):1733-46. doi: 10.1093/cercor/bhv007. Epub 2015 Jan 30.

Authors

Mark McAvoy¹, Anish Mitra¹, Rebecca S Coalson², Giovanni d'Avossa³, James L Keidel³, Steven E Petersen⁴, Marcus E Raichle⁵

Affiliations

¹ Department of Radiology, Washington University, Saint Louis, MO 63110, USA.
² Department of Radiology, Washington University, Saint Louis, MO 63110, USA Department of Neurology, Washington University, Saint Louis, MO 63110, USA.
³ School of Psychology, Bangor University, Bangor, UK.
⁴ Department of Radiology, Washington University, Saint Louis, MO 63110, USA Department of Neurology, Washington University, Saint Louis, MO 63110, USA Department of Anatomy and Neurobiology, Washington University, Saint Louis, MO 63110, USA Department of Neurosurgery, Washington University, Saint Louis, MO 63110, USA Department of Psychology, Washington University, Saint Louis, MO 63110, USA Department of Biomedical Engineering, Washington University, Saint Louis, MO 63110, USA.
⁵ Department of Radiology, Washington University, Saint Louis, MO 63110, USA Department of Neurology, Washington University, Saint Louis, MO 63110, USA Department of Anatomy and Neurobiology, Washington University, Saint Louis, MO 63110, USA Department of Biomedical Engineering, Washington University, Saint Louis, MO 63110, USA.

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.

Keywords: attention network; global signal; hemispheric asymmetry; resting-state; semantic network.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Adult
Brain / physiology*
Brain Mapping / methods*
Comprehension / physiology
Female
Functional Laterality*
Humans
Judgment / physiology
Language*
Magnetic Resonance Imaging / methods*
Male
Semantics
Young Adult

Abstract

Publication types

MeSH terms

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