TBI Recovery Mechanisms

1. What is brain plasticity? What influences it and what are the mechanisms by which it occurs?
2. How does neuronal regeneration differ from reorganization/unmasking?
3. What is diaschisis and how does it explain spontaneous return of brain function?
4. How does redundancy contribute to brain injury recovery?
5. How does vicariation contribute to brain injury recovery?

Answers:
1. Brain plasticity is the capability of the damaged brain to repair itself by morphologic and physiologic responses. It's influenced by the environment, stimulation, repetition of tasks, and motivation. It occurs by neuronal regeneration, collateral sprouting, and neural reorganization/unmasking.
2. Neuronal regeneration occurs when intact axons establish new synaptic connections via sprouting, occurring weeks to months post-injury. Functional reorganization/unmasking occurs when healthy neuronal structures are reassigned to a new function formerly done by the damaged area.
3. Diaschisis is when a lesion to one area of the brain produces altered function in another area of the brain that is connected to the damaged area by fiber tracts. Recovery of functions controlled by the remote site parallels recovery of the focal lesion.
4. Redundancy is when there are areas of uninjured brain that contributed to the function of the injured area, and after injury, take over that function.
5. Vicariation is when uninjured areas change their properties to take over the lost function.