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James Herman, Richard Krauzlis; Control of Spatial Attention by the Primate Superior Colliculus. Journal of Vision 2015;15(12):178. doi: 10.1167/15.12.178.
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© ARVO (1962-2015); The Authors (2016-present)
The primate Superior Colliculus (SC) plays a causal role in controlling spatial attention. Microstimulation of the SC improves detection performance at a specific spatial location. Inactivation of the SC causes both a spatially specific deficit for stimuli inside the affected area of the visual field, and an increase in distractability for stimuli outside the affected area. However, all these studies used motion stimuli. To determine the scope of the SC’s role in controlling spatial attention, we instead used color, a feature dimension that has only recently been appreciated as having importance in the SC. In separate sessions, we recorded SC neuronal activity or reversibly inactivated SC neurons with muscimol, while a monkey performed a demanding covert attention task utilizing dynamic color stimuli described previously (Herman & Krauzlis, 2014). The animal’s task was to respond to color changes in the “cued” stimulus by releasing a joystick and to ignore changes in a second, uncued “foil” stimulus. Color changes were physically isoluminant saturation increases, masked by luminance noise, and kept near the monkey’s detection threshold (80%). In most neurons (62/66) color changes evoked brisk firing rate increases, often exceeding that evoked by stimulus onsets (43/66). Also, change-related activity was greater when the animal released the joystick than when he maintained his hold, both for cued and foil changes. Complementing these neuronal data, we found that SC inactivation had a dramatic effect on the monkey’s task performance (6 sessions). When the cued stimulus was presented inside the affected area, hit rate dropped from an average of 68% to 26%; concurrently, the animal’s rate of erroneously responding to foil changes outside the affected area jumped from 4% to 26%. We conclude that the SC is likely necessary for covert spatial attention regardless of visual feature dimension.
Meeting abstract presented at VSS 2015
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