[Involvement of thalamic nuclei in the formation of conditional avoidance reflexes in rats. II. Lesions of the midline nuclei].

Lesions of the habenular-paraventricularis-anterior complex of the thalamus caused a total impairment of conditioned avoidance response of hooded rats (Long-Evans-strain) in a jumping test, but not in a simple runway. The change of stereotyped avoidance reactions could be attained very slowly. Running speed was lower and the number of errors much higher using an alternation schedule. Lesions of the nucleus centralis medialis and partly of its surrounding caused less deficits. From the results may be suggested that regulatory interactions between general behavioural activation originating from the brain stem, motivational processes and the analyzer systems are disrupted.