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Koorosh Mirpour, James Bisley; Formation of the priority map by the reciprocal connections between LIP and FEF. Journal of Vision 2015;15(12):1257. doi: 10.1167/15.12.1257.
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© ARVO (1962-2015); The Authors (2016-present)
We are able to find objects in a cluttered scene quickly and effortlessly. To achieve this, the brain creates a priority map of the visual world, which incorporates both pre-attentive and cognitive inputs to represent the importance of stimuli in the scene, and which uses inhibitory tagging to track items that have been viewed. Eye movements are then guided by this map. We have previously shown that activity in the lateral intraparietal area (LIP) acts like a priority map, but the absolute responses do not correlate directly with behavior: they have to be normalized first. In this study we examined the responses of neurons in the frontal eye field (FEF), which has reciprocal connections with LIP, to test whether it contributes to the formation of the priority map. Animals searched through 5 potential targets and 5 distractors to find the target loaded with reward. After the stimuli appeared, the animals were free to move their eyes. Stimuli were spaced such that when the animal was looking at one stimulus, another was in the FEF neuron's receptive field. Most of the neurons fit into 4 main classes: neurons that responded preferentially to Ts; neurons that responded preferentially when a stimulus that had been fixated was in the response field, which could drive top-down inhibitory tagging seen in LIP; and neurons that initially showed an enhanced response to a stimulus that had been fixated, but then reversed their response preference 100-150 ms after the saccade. The late responses in this class matched our post-normalization predictions. The final class of neurons didn’t differential between search objects, but preferentially responded to the goal of the next saccade. Together these data suggest that the reciprocal connection between LIP and FEF creates the priority map that guides saccadic eye movements during active, goal directed visual search.
Meeting abstract presented at VSS 2015
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