guest post by Kayt Sukel
The human brain has a remarkably distinct shape. With its folds and valleys (gyri and sulci, respectively), there is no bodily organ like it. How and why does it have this accordion-like structure? That’s remained an open, and highly debated, question among neuroscientists. Some argued there must be some biological factors within neurons and supporting cells that program them to grow this way. Others hypothesized that the brain’s gulfs and valleys are due to simple physics—that is, the mechanical compression involved with developing inside the enclosed case of the skull. Now, work done at Harvard University and Finland’s University of Jyväskylä suggests the latter argument may be the correct one.
“The number, size, shape, and position of neuronal cells during brain growth all lead to the expansion of the gray matter, known as the cortex, relative to the underlying white matter,” says Lakshminarayanan Mahadevan, a physicist and applied mathematician at Harvard. “This puts the cortex under compression leading to a mechanical instability that causes it to crease locally, a process called gyrification.” Continue reading