Influences of cortico-pretectal fibers on responses of rat pretectal neurons.
Responses of pretectal cells were studied following cortical excitation and inactivation in anesthetized rats. The visual cortex was excited electrically and by a topical application of strychnine while it was inactivated by a reversible cryoblockade. In a few experiments the superior colliculus was locally depressed by microinjections of lidocaine hydrochloride. Results showed a large spectrum of response latencies to electrical stimulations of the optic chiasm and visual cortex, and a significant correlation between responses to both sites of stimulation. It appears that pretectal cell responses strongly depend upon corticofugal impulses, as the disruption of the latter results in a profound decline of pretectal discharges. The suppressed-by-light cells were the most affected by a cryoblockade while the ON-tonic units were the least affected. The same types of cells were affected at the retinal level by cortical blockade.
Molotchnikoff
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Département de Sciences Biologiques, Université de Montréal, Que., Canada.
Cérat
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Casanova
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D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D004558:Electric Stimulation; D009474:Neurons / Q000502:physiology*; D009897:Optic Chiasm / Q000502:physiology; D051381:Rats; D013477:Superior Colliculi / Q000166:cytology / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology