Organization of bigger brains shows how thinking drives brain development

2018

Challenge

While it has long been observed that adult brains vary considerably in shape and size, the reasons for this have not been well understood.

Advance

IRP researchers, led Armin Raznahan, M.D., Ph.D., worked with collaborators from more than six additional research centers to analyze structural brain data from more than 3,000 people. They ultimately discovered that differences in brain size are related to the brain’s shape and how it is organized. Specifically, the bigger the brain, the more its additional area is accounted for by growth in thinking areas in the outer layer of the brain, known as the cerebral cortex, at the expense of relatively slower growth in lower-order emotional, sensory, and motor areas.

Impact

The fact that larger brains tend to have oversized areas devoted to thinking suggests that thinking drives the way brains develop, function, and look. Moreover, since people with certain psychiatric illnesses show alterations in brain size related to genetic influences, these new cortex maps may improve understanding of altered brain organization in psychiatric disorders. Finally, the research points to the need to take differences in brain size and organization into account to ensure accurate comparisons when studying groups of individuals with differing brain sizes, as often occurs in psychiatric research.

Publications

Reardon PK, Seidlitz J, Vandekar S, Liu S, Patel R, Park MTM, Alexander-Bloch A, Clasen LS, Blumenthal JD, Lalonde FM, Giedd JN, Gur R, Gur R, Lerch JP, Chakravarty MM, Satterthwaite T, Shinohara RT, Raznahan A. (2018). Normative brain size variation and brain shape diversity in humans. Science. 360:1222-1227.