Figure 11.

Schematic diagram of connections of the cMRF and the nucleus RIP in a circuit model for control of fixation and saccades. During saccades, the SC activates EBNs and IBNs in the PPRF, either directly or via LLBNs. cMRF neurons also receive saccade signals from SC. The GABAergic inhibitory cMRF reticuloraphe neurons help shut down glycinergic RIP activity, which in turn disinhibits EBNs and IBNs. Glycinergic inhibitory projections from the PPRF also contribute to silencing the omnipause cells. During fixation, SC fixation zone neurons send excitatory predorsal bundle inputs to RIP, which activates OPNs. These in turn suppress the activity of EBNs and IBNs. Non-GABAergic cMRF neurons also receive input from the SC fixation neurons and contribute to the fixation-related activation of RIP neurons. Solid green line arrows and “+” stand for excitatory projections, and dashed red line arrows and “−” indicate GABAergic inhibitory projections. Solid red line arrows and − indicate inhibitory glycinergic projections.