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Subcortical vision in cats
357 1 Goodale, M. A. and Lister, T. M., Attention to novel stimuli in rats with lesions of the superior colliculus, Brain Research, 66 (1974) 361-362. 2 Goodale, M. A., Milner, A. D. and Rose, J. E. V., Susceptibility to startle during ongoing behaviour following collicular lesions in the rat, Neurosci. Letters, 1 (1975) 333-337. 3 Goodale, M. A. and Murison, R. C. C., The effects of lesions of the superior colliculus on locomotor orientation and the orienting reflex in the rat, Brain Research, 88 (1975) 243-261.
Subcortical vision in cats KERSTIN NORRSELL - - Departments of Physiology and Ophthalmology, University of Gfteborg, G6teborg (Sweden) In a study ofmidbrain vision, Sprague described a total contralateral hemianopia after unilateral removal of the occipito-temporal neocortex in the cat. Subsequent removal of the superior colliculus on the opposite side made visual responses return to the previously hemianopic field. These results have been confirmed and elaborated (cf. ref. 2 for references) and have been suggested to indicate interaction between 'cortical' and 'collicular' vision. Since it is hard to test vision in an animal's hemianopic field in the presence of an intact visual half-field, another approach to the problem of midbrain vision was used in the present study. Removal of the neocortex of one hemisphere and section of the contralateral optic tract were performed in adult cats in two stages. Spontaneous behaviour was observed and discrimination in a T-maze (cf. ref. 1 for method) was tested before and after the operations. Two of the animals have been studied for more than a year after the second operation. When walking on a floor they frequently bump into obstacles. They refuse to jump from platforms, but will walk down if able to feel the lower surface with the paws. They cannot find the openings between rooms when placed in a fourroom labyrinth. When put in a cage, with one wall made of vertical bars, they are unable to retrieve pieces offish from outside the bars (they were very skilled in this performance before the second operation) - - on the other hand, the cats are not completely blind. In a T-maze one of the cats has reached a high level in discriminating a black from a white object and another cat is learning this task. Vision in the absence of the cerebral cortex thus appears to be poor in the cat. It can be utilized in special situations but probably not in everyday life. This finding could be confused by the presence of inhibitory influences from the remaining deafferented but otherwise intact visual centres indicated by the findings of Sprague and others. It remains to be seen if removal of the superior colliculus ipsilateral to the remaining hemisphere would improve these cats' rudimentary vision. 1 Norrsell, K. and Norrsell, U., Visual discrimination after total neonatal removal of the neocortex in the cat, Actaphysiol. scand., 84 (1972) 29-30A. 2 Sherman, S. M., Visual fields of cats with cortical and tectal lesions, Science, 185 (1974) 355-357.
Subcortical vision in cats KERSTIN NORRSELL - - Departments of Physiology and Ophthalmology, University of Gfteborg, G6teborg (Sweden) In a study ofmidbrain vision, Sprague described a total contralateral hemianopia after unilateral removal of the occipito-temporal neocortex in the cat. Subsequent removal of the superior colliculus on the opposite side made visual responses return to the previously hemianopic field. These results have been confirmed and elaborated (cf. ref. 2 for references) and have been suggested to indicate interaction between 'cortical' and 'collicular' vision. Since it is hard to test vision in an animal's hemianopic field in the presence of an intact visual half-field, another approach to the problem of midbrain vision was used in the present study. Removal of the neocortex of one hemisphere and section of the contralateral optic tract were performed in adult cats in two stages. Spontaneous behaviour was observed and discrimination in a T-maze (cf. ref. 1 for method) was tested before and after the operations. Two of the animals have been studied for more than a year after the second operation. When walking on a floor they frequently bump into obstacles. They refuse to jump from platforms, but will walk down if able to feel the lower surface with the paws. They cannot find the openings between rooms when placed in a fourroom labyrinth. When put in a cage, with one wall made of vertical bars, they are unable to retrieve pieces offish from outside the bars (they were very skilled in this performance before the second operation) - - on the other hand, the cats are not completely blind. In a T-maze one of the cats has reached a high level in discriminating a black from a white object and another cat is learning this task. Vision in the absence of the cerebral cortex thus appears to be poor in the cat. It can be utilized in special situations but probably not in everyday life. This finding could be confused by the presence of inhibitory influences from the remaining deafferented but otherwise intact visual centres indicated by the findings of Sprague and others. It remains to be seen if removal of the superior colliculus ipsilateral to the remaining hemisphere would improve these cats' rudimentary vision. 1 Norrsell, K. and Norrsell, U., Visual discrimination after total neonatal removal of the neocortex in the cat, Actaphysiol. scand., 84 (1972) 29-30A. 2 Sherman, S. M., Visual fields of cats with cortical and tectal lesions, Science, 185 (1974) 355-357.