Excitatory and inhibitory synaptic inputs from the medial mesodiencephalic junction to vertical eye movement-related motoneurons in the cat oculomotor nucleus.

The nature of synaptic inputs from the medial mesodiencephalic junction to motoneurons in the oculomotor nucleus innervating the superior and inferior rectus muscles was investigated in anesthetized cats, using intracellular recording techniques. Stimulation of the region produced mono- or disynaptic EPSPs and IPSPs in inferior and superior rectus motoneurons, respectively, on both sides. In a number of superior rectus motoneurons, EPSP-IPSPs or EPSPs were also induced in a similar latency range. The effective sites for inducing the monosynaptic PSPs were found within and near the dorsomedial part of the campus prerubralis.