Regu le 9 f6vrier, 1970
Septal Lesions in Apodemus Sylvaticus L.Ce travail a b6n6fici6 de l'appui du Fonds National Suissc de la Recherche Seientifique, cr6dit no 4383Summary. Lesions placed in the septum of wild mice (Apodemus Sylvaticus L.) result in a loss of the earth digging behaviour though the overall activity is increased during 15--20 days after the operation. Food intake and motricity are not impaired.If the animal is provided with an artificial nest including a door allowing to record the number of entries and exits one may observe that some of the animals are going in and out of that nest up to 100 times in 24 hours after they have been submitted to a septal lesion. Before having been operated the same animals were only coming in and out of the nest about ten times in 24 hours. This observation points to the fact that the rhythms of spontaneous activity are deeply altered after a septal lesion, due to inadequate inhibition.In most of the observed animals the impairement of the earth digging behaviour was proportional to the volume of tissue destroyed in the septum but on the other hand no correlations seems to exist between the size of the destroyed area and the increase of the overall activity after a septal lesion.The continuous and quantitative record of the overall activity of the free animal and the use of Nauta's technique for the histological control --already undertaken --are going to bring a better understanding of the neuroanatomical and physiological basis of the studied behaviours.