Evidence from intrinsic activity that asymmetry of the human brain is controlled by multiple factors

TLDR

Cerebral lateralization is a fundamental property of the human brain and a marker of successful development. The study provides evidence that multiple mechanisms control asymmetry for distinct brain systems. Using intrinsic activity in 300 adults, the authors mapped strongly lateralized regions, identified four distinct factors linked to vision, the default network, attention, and language, and showed that hand dominance differentially affects these factors. The study found strong asymmetries in both sexes, a small sex difference, and that hand dominance differentially influences the four identified factors, demonstrating that intrinsic activity can measure asymmetry and that multiple genetic or environmental mechanisms likely control cerebral lateralization.

Abstract

Cerebral lateralization is a fundamental property of the human brain and a marker of successful development. Here we provide evidence that multiple mechanisms control asymmetry for distinct brain systems. Using intrinsic activity to measure asymmetry in 300 adults, we mapped the most strongly lateralized brain regions. Both men and women showed strong asymmetries with a significant, but small, group difference. Factor analysis on the asymmetric regions revealed 4 separate factors that each accounted for significant variation across subjects. The factors were associated with brain systems involved in vision, internal thought (the default network), attention, and language. An independent sample of right- and left-handed individuals showed that hand dominance affects brain asymmetry but differentially across the 4 factors supporting their independence. These findings show the feasibility of measuring brain asymmetry using intrinsic activity fluctuations and suggest that multiple genetic or environmental mechanisms control cerebral lateralization.