Colliculoreticular organization in primate oculomotor system

Abstract

Systematic electrical stimulation of the superior colliculus in the alert monkey was used to characterize the patterns of its synaptic corrections with the pontine reticular formation (PRF). Eye movement-related (EMR) and non-eye movement-related (NEMR) neurons were found in this area. On the average, more NEMR units received collicular inputs than did EMR types, but with longer mean synaptic latencies. Saccadic-related units were activated from all regions of the colliculus in the mono-to disynaptic range. The rostolateral (foveal) colliculus possessed the highest percentage of monosynaptic connections with these units. Approximately 1/3 of the NEMR units were classified as attention-related. Almost all of these received collicular inputs, but at the longest mean synaptic latency of any PRF units. Analysis of the results of collicular stimulation on the firing patterns of EMR units demonstrated several neural mechanisms that might be involved in the spatial-to-temporal transformation underlying precise saccadic eye movements.