Some people with half a brain have extra strong neural connections

Half of a brain can do a full-time job.

A detailed study of six adults who, as children, had half of their brain removed to treat severe epilepsy, shows how brains can reorganize and bounce back. As extreme as the surgery is, many of these people keep or recover language and thinking skills. In a new study, researchers from Caltech and their colleagues discovered one way the brain might compensate.

While the six participants rested in an MRI scanner, researchers measured blood flow in seven brain regions that handle jobs such as vision, attention and movement. In the experiment, blood flow served as a proxy for brain activity. When activity in one part of the brain changes in lockstep with activity in another, that implies that the regions are working together and sharing information. These are signs of strong connections, which are thought to be crucial for a healthy brain.

In the six people who had had hemispherectomies, these seven brain systems seemed to be working normally. In fact, the connections between those seven systems were even stronger than such connections in six people with whole brains, the researchers report November 19 in Cell Reports. Such stronger-than-normal connections might help explain how these post-surgery brains compensate for missing parts, the researchers suspect.

Understanding more about how the brain reorganizes itself after a big change could lead to new approaches to speed people’s recoveries from common brain injuries.