Visual form perception is a function of the visual cortex

Abstract

Rats prepared with serial visual-cortical ablations can relearn the horizontal-vertical stripes discrimination problem if given interoperative training. However, they fail to discriminate between obliquely oriented stripes. The findings are discussed in relation to the concept that pattern perception is completely dependent upon the integrity of cortically related systems. Furthermore, the criteria for constructing pattern discriminanda are outlined, and reasons are presented for abandoning some of the classical stimuli used to test form perception in striate-extra-striate preparations.It is thoroughly established that if rats are given training on a black-white discrimination problem and then subjected to bilateral ablations of the posterior cortex, they show no postoperative retention of performance of the problem but can nonetheless relearn it. Lashley (1935) believed that relearning of the problem was a function of subcortical systems, and his concept has since been supported by Horel, Bettinger, Royce, and Meyer (1966) and Meyer, Yutzey, Dalby, and Meyer (1968). The latter studies have shown that the problem is relearnable by rats with complete neocortical ablations, regardless of whether the ablations are performed with one-stage or two-stage procedures.More recent research has been directed toward assessments of the variables which govern the rate at which the problem is relearned by rats with posterior ablations . One of the approaches has involved the use of procedures in which the animals are trained on the problem, subjected to unilateral posterior cortical ablations, then given inter operative retraining on the problem, SUbjected to second-stage ablations of the contralateral cortex, and then re-retrained on the problem. When this serial unilateral method is employed, the problem is finally relearned at a rate that is faster than the rate at which the problem is relearned by one-stage bilateral posterior preparations, or by subjects with two-stage posterior ablations which receive no interoperative practice

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

“…The finding was interesting because the OB problem is completely and permanently insoluble by rats with injuries to the posterior cortex (Horel, Bettinger, Royce, & Meyer, 1966;Jonason et aI., 1970;Lavond, Hata, Gray, Geckler, Meyer, & Meyer, 1978). Hence, if there is, in fact, a consequence of OB training for postoperative performance of the BW problem, the conse- quence is uninterpretable in terms of transfer of training that is mediated via reactions to discriminative cues that are present in both situations.…”

“…Hence, in Table 4, we summarize results from experiments con- Glendenning (1972); KBMM to Kircher, Braun, Meyer, and Meyer (1970); ALEE to an unpublished study of Aileen Lee that is described by Meyer and Meyer (1977); LHGM to Lavond, Hata, Gray, Geckler, Meyer, and Meyer (1978); and GRAY to the present report. All of the data in the table were collected in experiments in which measures of rates of relearning of the BW problem by rats with injuries to the visual cortex were obtained.…”

“…Group BWOT-UVC-BWOT-UVC-BW rapidly relearned the problem following the first-stage ablations; their score of 3.5 mean trials was the lowest that has been observed in our program for subjects which are retrained on the problem following a unilateral posterior injury. The subjects which were given OBOT between operations required about as many trials to learn the task as naive normal animals, and about twice as many as unilateral subjects with preoperative OB training (Lavond et al, 1978).…”

The cerebral cortex: Its roles in memory storage and remembering

“…We now interpret that result to mean that retraining after any injury to the cortex will induce a complete protection of remembering after any further injury that does not complete the destruction of the posterior cortex. In the latter circumstance, a second-stage injury will have a cost of 8 mean trials, and that is because interoperative training will not protect the subject from impairments which result from its not being able to perceive forms (Horel et al , 1966;Lavond & Dewberry, 1980;Lavond, Hata, Gray, Geckler, P Meyer, 1978).…”

Recovery of visual pattern discrimination by rats without visual cortex when trained by fading procedure

“…Numerous previous works (Bauer & Cooper, 1964;Bland & Cooper, 1970;Cooper, Blochert, Gillespie, & Miller, 1972;Lavond et al, 1978;Murphy & Chow, 1974;Schilder, Pasik, & Pasik, 1967, 1971, 1972Spear & Baumann, 1979;Spear & Braun, 1969;Weiskrantz, 1963;Winans, 1971) have discussed the question of whether subjects use the same cues or different ones to solve a visual discrimination task before and after a visual cortex injury.…”