Projections of vertical eye movement-related and head rotation-related neurons in the medial mesodiencephalic junction to pontine reticular formation in cat.

Spikes of single neurons related to vertical eye movements and vertical head rotation were recorded extracellularly in the medial mesodiencephalic junction (MDJ) of chronically prepared alert cats, and their antidromic responses to stimulation of the pontine reticular formation (PRF) were studied. Among the vertical eye movement-related-neurons, augmenting neurons (ANs) and tonic neurons (TNs) were activated antidromically from the lateral PRF. Stimulation of the midline PRF activated antidromically mainly ANs, long-lead burst neurons (LLBNs) and upward medium-lead burst neurons (MLBNs). The head rotation-related neurons were antidromically activated from the lateral PRF but not-from the midline PRF. These results suggest that some MDJ neurons related to vertical eye movements or head rotation directly project to the paramedian PRF.