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Abstract

Presented at the The Society for Neuroscience Annual Conference 2013

As we interact with our environment, the features of objects in the visual scene are not consistently present on the retina and sensory cues used to guide visual behavior are not always available. Thus, active observers are faced with a ubiquitous task of comparing sensory stimuli across time and space. When monkeys compare directions of visual motion of two stimuli presented at the fovea, S1 and S2, separated by a delay, neurons in the dorsolateral prefrontal cortex (DLPFC) show direction selective (DS) responses suggestive of their origins in area MT. In addition, responses during S2, the comparison stage of the task, are often modulated by the direction presented during S1. However, DLPFC neurons respond to motion not only at the fovea but also across the entire visual field, receiving direct bottom-up inputs from neurons in the ipsilateral MT representing contralateral stimuli and indirectly from the opposite MT representing ipsilateral stimuli. We examined whether DLPFC retains the spatial specificity in DS characteristic of its retinotopic inputs by presenting stimuli in the contralateral and ipsilateral hemifields during the direction comparison task. We found that responses to visual motion of many DLPFC neurons changed with location: they were more likely to be DS and this selectivity emerged earlier when stimuli appeared in the contralateral field. Preferred directions of neurons with DS for contralateral and ipsilateral stimuli were strongly correlated, suggesting alignment of direction information arriving in DLPF from MT neurons residing in the opposite hemispheres. Finally, response modulation during S2 also depended on stimulus location, weakening when the preceding S1 appeared in the opposite hemifield, suggesting participation of retinotopically organized cortical regions in the comparison process. Our results show that representation of visual motion in DLPFC is likely to be governed by its direct and indirect connectivity with area MT. The strong correlation between direction preferences in the two hemifields points to a mechanism that may facilitate integration of motion information across the visual field.