The possibility that the nigro-striatal dopaminergic system is involved in learning processes was tested by damaging the substantia nigra (SN) of the rat either electrolytically or neurochemically and testing the animals for deficits on a one-way active-avoidance task and a simple appetitive task. In Experiment 1 the animals were tested to determine whether the lesion resulted in increased freezing following footshock (FS) or in changes in general activity. No such differences were revealed.

more »

... deficit in active-avoidance learning observed in Experiment 2a could then be attributed to a disruption of the learning process following nigro-striatal system damage. However, these results must be qualified by the results of Experiment 2b in which it was observed that the experimental animals were less sensitive to FS than the controls. In experiment 3 an appetitive task was used to overcome the confounding effects of footshock and avoidance paradigms. Testing revealed a deficit in learning following damage to the nigro-striatal system. These combined results strongly suggest that the nigro-striatal dopamine system is an integral part of the neural substrate of learning.