Some observations on the problem of recovery of function following brain damage.

Functional restitution following brain damage can occur either because of a return of the original function or because of compensatory changes involving functional substitution. In any study of post-traumatic recovery it is important to use an experimental model which can discriminate between these separate mechanisms. Recovery from unilateral frontal eye-field damage was used as a model in both monkeys and rats. In particular, the role of the intact hemisphere in the recovery process was examined. Section of the corpus callosum was found to restore the original visual neglect both in monkey and in rat; indicating that that recovery was due to adaptation mechanisms in the intact hemisphere. Pseudo-recovery that was seen on occasion in monkeys was not a return of the original control processes, but was an improvement due to the adoption of new behavioural strategies.