Learning ability in young rats with single and double lesions to the "general learning system"

Previous lesion studies suggest that the dorsal caudatoputamen (DCP), globus pallidus, ventrolateral thalamus (VLT), substantia nigra, ventral tegmental area, superior colliculus (SC), median raphe, and pontine reticular formation are components of the general learning system (GLS) of the rat brain. The current study attempted to determine whether bilateral lesions to two components of the GLS (DCP/VLT, DCP/SC or VLT/SC) would produce greater deterioration of learning ability than bilateral lesions to only one component (DCP, VLT or SC). In all combinations examined, a second lesion added to the first led to a significantly greater learning decrement on a series of spatial reversal problems than that associated with the first lesion alone. These results are compatible with the view that the foregoing structures are elements of the same functional system concerned either directly or indirectly with general learning ability.