Dynamics and bases of recoveries of functions after injuries to the cerebral cortex

Abstract

A review of the principal results of a 20-year program, at Ohio State University, of quantitative studies of the problem of recovery from damage to the brain.This review considers the principal results of a program of quantitative studies of the problem of recovery from damage to the brain. The program was begun some 20 years ago as an effort to understand the curious results of a classical experiment of Lashley (1935). Lashley observed that if hooded rats are trained to choose the brighter of a pair of doors, they show no postoperative retention of the habit when retested after having been subjected to bilateral ablations of the posterior regions of the dorsolateral cortex. But he also observed that posterior preparations, if given further training on the task, relearn the black-white habit at a rate that is not very different from the rate at which the habit is initially acquired by normal subjects.Lashley's observations thus suggested that retention of the habit could be readily suppressed by an ablation that is virtually without effect upon a rat's capacities for learning or relearning of the habit. Hence, the first question was why, if it is true that the habit can be learned just as quickly by braindamaged subjects as by normal animals, performance of the habit should be cortically dependent provided that the cortex is present. That is, the animals had obviously not been reduced to a condition where they lacked some essential system for performance of the habit, and yet they behaved as though the operations had deprived them of all recognition of the fact that they had ever seen the problem before.The investigations described in this review were supported in part by National Institute of Mental Health Grants MH-02035 and MH-D6211. P. M. Meyer is a United States Public Health Service Research Scientist and Investigator (5-Ko-MH-12,747) of the National Institute of Mental Health . From the Laboratory of Comparative and Physiological Psychology, Ohio State University: To our former students, whose thoughts, skills, and labor have contributed so much to the conception, design, and execution of the studies in the program, we express our deep appreciation and our fondest regards. We also wish to thank Ms. Elaine Wells Carlson for her assistance in the preparation of the manuscript. And, finally, we wish to note that David G. Lavond, who subjected the draft to an unusually constructive critique, enabled us to see some implications in the findings that had theretofore completely escaped us.A second basic question was whether, in recovering from ablations of the posterior cortex, the subjects were relearning the habit with systems related to the still-intact anterior cortex. We found that there were two ways of looking at that possibility. One was to presume, as Pavlov (1927) had proposed, that recoveries of visual habits that are lost when the posterior cortex is destroyed is possible because the anterior cortex normally has visual as well as other kinds of functions. The other was to think that the anterior corte...

The cerebral cortex: Its roles in memory storage and remembering

“…However, that result was obtained through the use of methods we no Ionger employ (cf. D. R. Meyer & P. M. Meyer, 1977), and hence we believe that it needs further close examination.…”

Discriminative avoidance learning in hippocampal and cortical rats: Acquisition rate, behavioral strategies, and long-term retention

“…A Thompson-Bryant box served as the conditioned avoidance apparatus; this has been described in detail elsewhere (Meyer & Meyer, 1977). Briefly, it consisted of a startbox, connected to a choice area by a hinged door.…”

“…The results cannot be easily explained in terms of a tendency to lateral perseveration, since the first two trials were lateral alternations. Meyer and Meyer (1977) report retention deficits in rats with cortical lesions on the same task that we use in our experiments. Their animals were trained before the lesion, and the results replicated the findings of Lashley.…”

Perinatal injuries to extravisual cortex enhance the significance of visual cortex for performance of a visual habit

“…The habits thus established are extremely persistent after injuries to the dorsolateral cortex (cf. Meyer & Meyer, 1977), and therefore the subjects were pretrained before training (OL) but not before their tests for retention (RL) .…”