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Ibotenic acid lesions of the substantia nigra pars reticulata ipsilateral to a visual cortical lesion fail to restore visual orienting responses in the cat
Author(s) -
Ciaramitaro Vivian M.,
Wallace Steven F.,
Rosenquist Alan C.
Publication year - 1997
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19970127)377:4<596::aid-cne9>3.0.co;2-y
Subject(s) - superior colliculus , ibotenic acid , neuroscience , lesion , substantia nigra , disinhibition , psychology , receptive field , visual field , visual cortex , biology , pars reticulata , anatomy , central nervous system , dopamine , dopaminergic , psychiatry
Unilateral removal of all known visual cortical areas in the cat renders the animal hemianopic in the contralateral visual field as measured by visual perimetry and other behavioral tests. We have shown that visual orientation behavior can be restored to the previously blind hemifield by destruction of a critical zone in the substantia nigra pars reticulata contralateral to a cortical lesion (Wallace et al., J. Comp. Neurol. 296:222–252, 1990). The model proposed to explain this recovery postulates that damage to the crossed nigrotectal projection disinhibits the superior colliculus ipsilateral to the cortical lesion and this leads to recovery. If disinhibition can account for recovery, then destruction of the uncrossed nigrotectal projection, which is known to exert a tonic inhibition on the superior colliculus, should also result in recovery. We made unilateral visual cortical ablations and ipsilateral ibotenic acid lesions of the substantia nigra pars reticulata. Visual orienting behavior was assessed in animals for a period of 4 to 31 weeks. Contrary to the prediction of the model, we failed to observe a recovery of visual orienting behavior in the blind hemifield in any of 23 animals. J Comp Neurol 377:596–610, 1997. © 1997 Wiley‐Liss, Inc.