Gyral development of the human brain

TLDR

The study aimed to chart the development of cerebral hemisphere convolution by examining photographs and sections of 507 and 207 infant brains aged 10–44 weeks gestation. Researchers tabulated sequential changes in fissures, sulci, and gyri and produced schematic drawings of monthly developmental shifts during the second and third trimesters. Twins exhibited a 2–3‑week delay in convolutional markings, no sex difference was observed, left‑right asymmetries were noted in temporal gyri, sylvian fissures, and planum temporale, and the right hemisphere showed earlier gyral complexity, suggesting possible links to speech and language development.

Abstract

Abstract To determine the development of the convolutional pattern of the cerebral hemispheres, we have examined multiple gross photographs of 507 brains and serial sections of 207 brains from infants of 10 to 44 weeks' gestational age. The sequential developmental changes of the individual fissures, sulci, and gyri of the cerebral hemispheres throughout the gestational period are tabulated. Schematic drawings made from enlarged photographs show the major changes associated with each month of the second and third trimesters. The brains of twins between 19 and 32 weeks' gestational age show a delay of approximately two to three weeks in the development of convolutional markings compared with the brains of nontwins. There is no significant difference between male and female brains. We found left‐right asymmetries of the transverse temporal gyri, sylvian fissures, and planum temporale. In general, the right cerebral hemisphere shows gyral complexity earlier than the left. Our findings allow speculation about the significance of left‐right asymmetry of the brain as it affects speech and language development.