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Biomedical subjects

H Ursin

Publications and source records attributed to H Ursin.

At least 91 records · Page 5Linked to original sources
PubMed1978

Exploration and avoidance in rats with lesions in amygdala and piriform cortex.

Lesions localized to specific areas of the amygdala and overlying cortex in rats produced differential effects in several behavioral tasks. Three different types of lesions were tested: central, basolateral, and cortex lateral to the amygdala. Lesions restricted to the central nucleus produced increased activity on all parameters studied in an open-field test, but the other two groups were not changed. In one-way active avoidance all three groups with lesions showed deficits. The most pronounced change was observed in the central group. All groups showed the same degree of retention loss, but in forced extinction of one-way active avoidance after retraining, the cortical and basolateral groups were most defective. A fear-reduction hypothesis is proposed for the central lesion. The basolateral and cortical areas may be more specifically involved in passive avoidance behavior.

Amygdala↗
PubMed1977

Multivariate analysis of the septal syndrome.

Since recent reviews of the behavioural effects of septal lesions agree that more than one explanatory concept is required, a multivariate analysis of the septal syndrome has been made. A total of 127 rats have been tested 73 with septal lesions and 54 controls. The rats were tested in a standard test battery consisting of a residential maze, spontaneous alternation, spatial learning, approach/avoidance conflict and one-way active avoidance. Factor analyses reveal a complex change in the factor structure after septal lesions. None of the previous explanations of septal functions receives unequivocal support. The findings do not exclude the possibility that septal lesions interfere with a few general behaviour mechanisms or perhaps only one. However, if so, this factor does not explain as much of the variance as expected. Situational or test-dependent factors play a greater role in the variance. This is interpreted as an indication of insufficiency in the theoretical structure, or in conventional test designs.

Animals↗
PubMed1976

Inhibition and the septal nuclei: breakdown of the single concept model.

The term inhibition has played an important role in the theoretical discussions on brain function since Sherrington and Pavlov. The interpretation of the term was a major issue in Konorski's monograph of 1948, and a main point of difference between his views and those of Pavlov. In his 1967 monograph Konorski revised and expanded his views on the various types of inhibitory phenomena. The term has also been used extensively in neuropsychology, in particular in research related to the frontal lobes and limbic structures. Among the limbic structures, it is the septal/subcallosal area that has received most attention from this point of view. The aim of this paper is to review how the term inhibition has been used in the analysis of the function of the septal nuclei, how this relates to Konorski's views on inhibition, and to what extent inhibition still is a useful explanatory concept in describing the behavioral role of these nuclei. The paper will not attempt to give a comprehensive review of the literature on the septal nuclei, excellent reviews are available (Fried 1972, Caplan 1973, Lubar and Numan 1973, Grossman 1975). Only those papers will be dealt with that are relevant for the theoretical positions discussed.

Animals↗
PubMed1975

Emotional behavior in feral cats with ablations of prefrontal cortex and subsequent lesions in amygdala.

Bilateral ablations of gyrus proreus in 6 feral cats did not significantly alter either the intensity or the pattern of flight behavior during confrontation with a human. The scores for defense behavior were reduced in only 2 animals. Subsequent lesions in the rostral part of the basolateral nuclei of amygdala reduced flight and transiently decreased defense scores in all cats. The prefrontal cortex does not seem necessary for the flight and defense responding observed in feral cats. The role of amygdala in the regulation of these behaviors was confirmed.

Amygdala↗