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Koorosh Mirpour, Fabrice Arcizet, James Bisley; Dynamics of the priority map in LIP during visual search. Journal of Vision 2008;8(6):991. doi: 10.1167/8.6.991.
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© ARVO (1962-2015); The Authors (2016-present)
When searching for an object in a scene we tend not to look at the same location over and over again. Modelers have suggested that after we have looked at a location, it is inhibited on the saliency map. We, and others, have proposed that activity in the lateral intraparietal area (LIP) acts as such a map, in which features or locations are represented by levels of activity related to the attentional priority at that location. Although, the neural activity of LIP area describes the attentional priority across the visual field, it is unclear how this priority map is updated during ongoing visual search. To investigate this, two monkeys were trained to perform a task in which they searched for a reward-loaded target among 5 targets and 5 distractors. After the stimuli appeared, the monkeys were free to move their eyes to find the reward-loaded target. Stimuli were spaced such that when looking at one stimulus, another was in the LIP neuron's receptive field. Although LIP neurons responded to both the targets that had and had not been already looked at, the responses were stronger to the targets that had not been seen. This difference could be the result of an eye movement to the target in the receptive field just before or after the analyzed epoch. This possibility was ruled out by showing that the responses to targets that had not been seen were still higher than targets that had been seen when the monkey had just made a saccade from that stimulus or was about to make a saccade directly to that stimulus. We suggest that the activity in LIP provides a priority map that encodes the location of interesting objects in the environment and dynamically keeps track of locations we have already looked at.
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