A question posted in Quora asks “How does the brain repair/rewire itself after a stroke or traumatic brain injury? Read the response from neuroscientist Paul King, and add your own thoughts to the comments.
The restoration of cognitive function following stroke most likely occurs by neural adaptations in the surrounding brain tissue that allow it to take over the function of lost neurons.
The first phase of repair is physiological: clearing away dead cells.
Not much is known about the specifics of how cognitive function is restored, however most likely what is happening amounts to a re-routing of information processing functions into healthy brain tissue.
In general, the brain does not produce new neurons in adulthood. The brain is, however, very malleable and adaptable in how information flows through its neural networks and how network regions are allocated to the task of cognition. This malleability comes about because information processing in the brain is highly “distributed.” While certain brain regions are specialized for certain functions, nearly all of the brain is working in unison on everything that the brain does all of the time.
As an analogy, if everyone in the marketing department of a large company disappeared one day, what would happen is that other people would take over their work. Salespeople, business development people, and others would pick up the slack and some might even become full-time marketing people. Initially they would do a bad job at marketing, but they would get better pretty quickly. The reason for fast improvement is that they were “involved” in marketing all along even though they weren’t primarily responsible. They probably even knew some things about the company’s marketing strategy just by being around it.
Similarly, related brain areas can take over the function of damaged areas. Time is required for surrounding network regions to adapt to a new function. This adaptation occurs by the strengthening and weakening of neural connections (synapses) throughout the network. New synapses may be formed as well, and alternate signal routing patterns need time to develop. The jerry-rigged modified functioning will not be as efficient as the original, but it is better than nothing.
