Abstract
The superior colliculus (SC) clearly plays a role in spatial attention in nonhuman primates, but the SC is a small, deep structure that is difficult to study in humans. However, it is possible to isolate SC-related processed by using monocular stimulation, because only the contralateral nasal hemiretina projects to the SC on a given side. Consequently, monocular presentation to the nasal versus temporal hemiretina of a given eye will cause the contralateral SC to be stimulated versus not stimulated. The present study adopted this approach using anaglyph lenses to control the eye of stimulation, in an oculomotor inhibition of return (IOR) task, making it possible for the first time to independently control the hemiretina of the cue and target . Each trial contained a cue in one of the four quadrants and then a target at the cued location or at one of the uncued locations, with no predictive relationship between the cue and target locations. Observers were instructed to make a rapid saccade to the target location. In a sample of 11 observers (24±5 years old), we found that IOR was significantly larger when both the cue and target were directed to the nasal hemiretinae compared to any other combination. This indicates that the SC plays a significant role in IOR, and it establishes a method that can be used in future research to determine the nature of the SC contribution to attentional orienting.
Meeting abstract presented at VSS 2013