Scientists decode how the human brain adapts to injury

When one brain area loses functionality, a "back-up" team of secondary brain areas immediately activates, replacing not only the unavailable area but also its confederates, researchers led by the Carnegie Mellon University's Center for Cognitive Brain Imaging (CCBI) found.

"The human brain has a remarkable ability to adapt to various types of trauma, such as traumatic brain injury and stroke, making it possible for people to continue functioning after key brain areas have been damaged," said researcher Marcel Just.

"It is now clear how the brain can naturally rebound from injuries and gives us indications of how individuals can train their brains to be prepared for easier recovery," Just said.

"The secret is to develop alternative thinking styles, the way a switch-hitter develops alternative batting styles. Then, if a muscle in one arm is injured, they can use the batting style that relies more on the uninjured arm," Just added.

Researchers used functional magnetic resonance imaging (fMRI) to study precisely how the brains of 16 healthy adults adapted to the temporary incapacitation of the Wernicke area, the brain's key region involved in language comprehension.

They applied Transcranial Magnetic Stimulation (TMS) in the middle of the fMRI scan to temporarily disable the Wernicke area in the participants' brains.

The participants, while in the MRI scanner, were performing a sentence comprehension task before, during and after the TMS was applied. Normally, the Wernicke area is a major player in sentence comprehension.

The research team used the fMRI scans to measure how the brain activity changed immediately following stimulation to the Wernicke area.

The results showed that as the brain function in the Wernicke area decreased following the application of TMS, a "back-up" team of secondary brain areas immediately became activated and coordinated, allowing the individual's thought process to continue with no decrease in comprehension performance.

The brain's back-up team consisted of three types of brain regions: contralateral areas - areas that are in the mirror-image location of the brain; areas that are right next to the impaired area; and a frontal executive area.

"The first two types of back-up areas have similar brain capabilities as the impaired Wernicke area, although they are less efficient at the capability," Just said in a statement.

"The third area plays a strategic role as in responding to the initial impairment and recruiting back-up areas with similar capabilities," Just added.

The research was published in journal Cerebral Cortex.