Recovery of function after brain damage: differential effects of blocking calcium uptake during the recovery of a learned behavior and the performance of the recovered behavior following neocortical brain injury.
The recovery of a learned behavior following brain damage is typically considered to have occurred when the brain-injured individual reattains the performance criterion that defined original preoperative learning. While this is obviously correct from an operational point of view, it does not necessarily mean that the consequences of the brain injury have been reversed, particularly with regard to the sustained performance of the supposedly recovered behavior. The present research attempted a more comprehensive evaluation of the behavioral effects of localized neocortical injury by investigating how a calcium channel blocker would effect (a) the original preoperative acquisition, (b) the initial postoperative recovery, and (c) the subsequent long-term performance of a brightness discrimination learned by rats subjected to injuries of their visual neocortex. The results demonstrated that notwithstanding the brain-injured rat's ability to reattain the performance criterion used to define preoperative learning, its long-term performance of this recovered behavior was significantly inferior to that of a normal rat. More importantly, the present data suggest that there are important differences between the initial postoperative recovery of a behavior and its long-term performance since the same drug that will facilitate initial recovery has just the opposite effect with respect to the animals long-term postoperative performance of the behavior.