We have a new review article in press about the fascinating visual functions of the primate superior colliculus (SC). The article appears in this year’s issue of Annual Review of Vision Science, and an early version of it can already be read at this link.
Our review article summarizes recent observations about the visual feature tuning properties of the SC, a brain structure that is commonly associated with controlling gaze shifts (e.g. eye movements), especially in primates. We show that the SC in primates is still a highly visual structure, as is the case in other species like mice.
We also show that the visual properties of the primate SC seem to be particularly optimized for exploiting the SC’s proximity to the brainstem and other circuits controlling eye and body movements. Thus, we argue that the SC does not simply inherit the visual properties of its cortical source areas (like the primary visual cortex). Rather, it exhibits functional specializations that can aid in guiding orienting eye and body movements, and also cognitive processes.
Throughout the article, we additionally demonstrate how the visual properties of the primate SC can also be extremely relevant during active behavior itself, an idea that culminates in the intriguing suggestion that even motor commands in the SC (for gaze shifts) are, in a sense, highly visual in nature. This idea is consistent with our recent observations about sensory tuning in saccade-related SC motor bursts, and it raises important questions about how the SC can provide important re-entrant visual signals into sensory areas as a means to stabilize and integrate perception across rapid retinal image shifts caused by a continuously moving eye.
Our ongoing research efforts in the lab aim at comparing the SC visual properties not only to those in the visual cortex, but also to potential feature-tuned visual signals in downstream brainstem eye movement control circuits. This latter comparison is particularly relevant to know what is the functional role of having such diverse visual pattern analysis capabilities in the SC only a few synapses away from the eye muscles.
