Effects of mixed training and overtraining on recoveries from amnesias in rats with visual cortical ablations

Abstract

This investigation was concerned with the question of whether amnesias for simple visual tasks which result from injuries to the visual cortex can be corrected via training on other visual tasks. Such effects were noted, but only when the problems shared a common mode of solution.It was also observed, in contradiction to a classical conclusion of Lashley, that extensive preoperative overtraining conveys some protection of postoperative performance of the blackwhite discrimination problem.Many years ago, Chow (1952) trained monkeys on visual discrimination problems of kinds that are not ordinarily rememberable by animals with injuries to the temporal isocortex. After operation, he trained his subjects on three new discrimination problems, and then found that their performance of the tasks they had learned prior to surgery was impaired hardly at all. Therefore he concluded that the temporal-lobe

Inductions of recoveries from injuries to the cortex: Dissociation of equipotential and regionally specific mechanisms

“…Several have confirmed his observation that ablations of the posterior neocortex will completely suppress postoperative performance on the black-white problem (e.g., Glendenning, 1972; Gray & Meyer, 1981;Horel, Bettinger, Royce, & Meyer, 1966;LeVere & Morlock, 1973;Meyer, Yutzey, Dalby, & Meyer, 1968;Petrinovich & Carew, 1969;Thompson, 1960), but that such injuries have a very small effect upon the rate at which the problem is learned by preoperatively naive subjects (Bodart, Hata, Meyer, & Meyer, 1980;Horel et aI., 1966;Jonason, Lauber, Robbins, Meyer, & Meyer, 1970;see Gray & Meyer, 1981, for review). Indeed, the sole discrepancy between his obThis research was supported by a grant in aid from the Donald Jansen Fund of Ohio State University.…”

“…Hence, unless other treatments are employed, there is no "serial lesion effect" (Finger, 1978;Finger, Walbran, & Stein, 1973). However, if two-stage posterior preparations are given inter operative retraining, they then exhibit sparing of ultimate performance on the black-white problem (Glendenning, 1972;Gray & Meyer, 1981;Thompson, 1960). That effect is not due simply to extra training, since equivalent amounts of overtraining prior to surgery fail to yield it (Glendenning, 1972;.…”

“…However, we also have a large amount of data that indicate that unilateral first-stage injuries to either the visual or extra visual cortex are followed by impairments that can be corrected by eight or nine spaced retraining trials (Gray & Meyer, 1981;. The standard errors of the scores for such subjects are approximately ± 1 trial, and the means are insensitive to small variations in the scopes of the injuries to the brain.…”

“…Consequently, the observed sparing is a facilitation of recall rather than a consequence of learning a new memory. Finally, the effect is explicitly a function of retraining on the black-white problem, since ultimate retention is not observed if the subjects are trained on other kinds of visual tasks between the operations (Davis & LeVere, 1982;Gray & Meyer, 1981). Now we shall consider the performances of subjects with one-stage bilateral ablations of the extravisual cortex.…”

The cerebral cortex: Its roles in memory storage and remembering

“…As we first showed many years ago, a normal rat that is trained on a problem and then prepared with an injury to the posterior half of its cortex will forget the problem, but will then relearn it in about as many trials as it takes for a naive posterior subject to learn the problem after surgery. The number of trials required in either instance will vary with the training conditions, but the near-equivalence of learning and relearning rates has been observed in many different contexts (Glendenning, 1972;Gray & D. R. Meyer, 1981;Horel, Bettinger, Royce, & D. R. Meyer, 1966;Lashley, 1935).…”