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Richard Krauzlis; A priority map for movement and perception in the primate superior colliculus. Journal of Vision 2009;9(14):10. doi: 10.1167/9.14.10.
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© ARVO (1962-2015); The Authors (2016-present)
“The primate SC is best known for the generation of saccadic eye movements, but our work shows that the SC supports a range of sensory-motor functions beyond the motor control of saccades. The unifying principle for these observations is that activity in the SC forms a priority map that represents the location of behaviorally relevant stimuli or objects. First, we have found that the SC is important for selecting the target for orienting responses, regardless of whether that target is acquired with a saccade, smooth pursuit, or fixation. Second, reflecting its retinotopic organization, the priority map in the SC includes the fovea and thus exerts control over even the smallest eye movements, including microsaccades. Third, activity in the SC represents the location of the behavioral goal or object, not the individual visual features that define the object. Consequently, focal inactivation of neurons in the SC produces a contant offset in eye position as subjects attempt to look at a visual object, consistent with the inactivation causing a biased estimate of that object's location. Finally, focal inactivation in the SC causes a dramatic impairment in the allocation of voluntary spatial attention, distinct from any effects on eye motor control. During SC inactivation, subjects have difficulty making perceptual judgments about stimuli in the affected portion of the visual field, but only when distracters containing counter-informative signals appeared in the unaffected field. These results demonstrate that the priority map in the SC is a bottleneck in the covert selection of signals for perceptual judgments, even in the absence of eye movements.
Together, this work shows that activity in the primate SC not only supports the formation of motor commands, but also plays a crucial role in selecting visual targets, representing the behavioral goal, and regulating how sensory information is used for perceptual decisions. These findings provide new insights into the mechanisms that control whether and when to move the eyes, and that link overt and covert orienting during active vision.”
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