Effects of dorsal, mediobasal and laterobasal septal lesions in the rat: Reflexive fighting and pain thresholds

The experiments were carried out on adult male rats of the Wistar strain, quality SPF. These were divided into experimental groups so that each group contained siblings. The functional differentiation of the rat septum was examined using the method of reflexive fighting on successive exposure to stimulating impulses. Rats with septal lesions differed from intact ones in a higher level of reflexive fighting during the first to ninth sessions. During the tenth to eighteenth sessions this difference was preserved but, in addition, differences became manifested between rats with septal lesions according to the localization of their lesions. The rats with laterobasal lesions had a lower level of reflexive fighting than those with dorsal and mediobasal lesions. The application of the technique of reaction to electric current showed likewise a functional differentiation of the septum; however, of all experimental criteria, the differences were found only in vocalization where control rats exhibited a higher threshold than those with septal lesions. Among the latter, those with dorsal lesions had a lower threshold than either the rats with mediobasal or laterobasal lesions. The participation of conditioned and unconditioned components in the mechanism of these phenomena is discussed.