The effects of lesions of the habenula nucleus on lever press behaviour during a tandem operant schedule with contrasting response requirements.

The effect of bilateral lesions of the habenula nuclei in male Lister hooded rats was assessed in performance of a well learned complex tandem operant reinforcement schedule. The schedule requirement involved two successive and contrasting components in which 15 operant lever press responses followed by inhibition of the same response for a period of 15 s provided liquid-food reinforcement. Initially little disruption of performance was seen when each component of the schedule was differentially signalled with an external cue. However, relative to controls, lesioned animals showed an increasing disruption of performance when such cues were omitted. The deficit in performance of lesioned animals was not a simple failure to inhibit responding that could be predicted from an altered input from septal areas. It is suggested that these behavioural data are consistent with the anatomical evidence for the habenula as a functional relay for the integration of information from limbic structures and the striatum and that lesions of the habenula affect the ability of animals to maintain effective response strategies, particularly when these are under intrinsic control.