Visual discrimination defects in cats with temporal or occipital decortications

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Investigated performance on visual discrimination problems by 7 control (C) cats, 8 cats with lesions in the posterior temporal (PT) cortex, and 8 with destruction of the central 3-20| of the retina's projection to the marginal (M) gyrus. Group PT was impaired on 7/11 initial learning and transfer tests and on 0/3 retention tests with pattern stimuli and was inferior to Group C on 1/7 object discrimination tasks. No discrimination contingency was more likely than the others to reveal a significant deficit in Group PT. Group M was not impaired relative to Group C on any individual discrimination task. However, it made significantly more total errors on 7 discriminations between complex patterns (embedded or masked figures) than Group C. On 3 discriminations between simple patterns (unmasked figures), Group M made fewer errors than Group C. This pattern of loss is qualitatively similar to but milder than that observed in previous cats with M lesions, probably because the present M lesions were relatively small. Findings indicate that M and PT ablations produce differential impairments in cats, a selective difficulty in differentiating complex patterns after M lesions and a nonselective disruption of pattern discrimination learning after PT lesions. (34 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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