Role of dorsal mesencephalic reticular formation and deep layers of superior colliculus as out-put stations for turning behaviour elicited from the substantia nigra pars reticulata.

In order to investigate the role of dorsal mesencephalic reticular formation (MRF) and deep layers of superior colliculus (DLSC) as out-put areas for non-dopamine mediated behavioural functions arising in the substantia nigra, discrete unilateral kainate-lesions as well as sham-lesions were placed in the MRF and DLSC. Ten days later kainate (0.75 microgram) was microinjected into the substantia nigra pars reticulata. Lesions of MRF as well as lesions of DLSC reduced the contralateral turning induced by kainate lesions of pars reticulata ipsilateral to the MRF or DLSC lesions. The lesions of MRF were more effective than lesions of DLSC. Lesions of MRF or DLSC on the side contralateral to intranigral kainate were ineffective. The results indicate that the MRF-DLSC complex is an essential area for the expression of motor behaviour elicited from the substantia nigra.