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G Winocur

Publications and source records attributed to G Winocur.

At least 73 records · Page 4Linked to original sources
PubMed1978

Effects of context manipulation on memory and reversal learning in rats with hippocampal lesions.

In Experiment 1, groups of hippocampal and control rats learned a simultaneous discrimination habit and were subsequently tested for its retention under variable contextual conditions. All groups recalled the discrimination response to an equally high level when testing conditions were constant throughout, but the hippocampal group showed impaired memory when contextual stimuli at recall testing did not conform to those of original learning. Experiment 2 indicated that the hippocampal impairment was not simply the result of introducing novel stimuli. In Experimental 3, animals were administered a reversal learning task with contextual stimuli varied between the two tests. The typically observed impairment of hippocampal animals on this task was reduced by contrasting contextual conditions. The data are seen to support a contex-tetrieval interpretation of hippocampal function.

Animals↗
PubMed1976

Effects of additional cues on passive avoidance learning and extinction in rats with hippocampal lesions.

Following the acquisition of a water-rewarded approach response in a straight runway, the effects of introducing shock in the goal box (passive avoidance - PA) or withdrawing reinforcement (extinction) were compared in hippocampal, cortical, and operated control groups of rats. Under standard test conditions, hippocampal groups were impaired in PA learning and showed strong resistance to extinction, relative to the control groups. When additional cues were provided such that external stimuli associated with goal box events could be easily detected early in the runway, performance differences between the hippocampal and control groups were eliminated in the PA test and significantly reduced in extinction. The results emphasize the inefficient processing by hippocampally-damaged animals of stimulus cues following a shift in experimental contingencies.

Animals↗
PubMed1971

Anemia in sleep-deprived rats receiving anticoagulants.

Independent groups of rats were deprived of sleep and treated with the anticoagulant drugs phenylindanedione or dicoumarol for 1 to 8 days. These animals developed an extremely severe anemia which was accelerated by p-chlorophenylalanine. The red cell count and amount of hemoglobin decreased to half of normal values. No decrease occurred in animals subjected to any one single treatment. Histological examination indicated hemolysis, hypoplasia of hemopoietic organs, slight hemorrhage, but no evidence of stress. The severity of the anemia was inversely related to the amount of sleep permitted during sleep deprivation. This new syndrome demonstrates marked effects of sleep deprivation on both maturation and destruction of red blood cells. Depletion of serotonin by injection of parachlorophenylalanine blocked the increase in amount of brain waves of the type commonly seen in slow wave sleep but did not eliminate the production of these waves. This result is at variance with the theory that serotonin is the neurochemical responsible for the "priming" of slow wave sleep.

Anemia↗