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Fabrice Arcizet, Caroline Charpentier, James Bisley; The effect of microstimulation of LIP during a change blindness task. Journal of Vision 2011;11(11):181. doi: https://doi.org/10.1167/11.11.181.
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© ARVO (1962-2015); The Authors (2016-present)
When scanning a scene, our attention can be allocated according to the attentional priority of the objects present in the scene. These priorities are represented by peaks of activity in the lateral intraparietal area (LIP), which we have proposed acts as a priority map. In this study, we are interested in understanding how the brain uses the activity in LIP to allocate covert attention. To examine this, we artificially manipulated activity in the priority map by microstimulating LIP while two animals performed a change blindness task. A trial started when the animal fixated a central white spot for 900 to 1300 ms. Then, 4 oriented bars were flashed for 500 ms at equal eccentricities; one of the bars was at the center of the neurons' receptive field (RF). After a gap of 50–150 ms, the bars reappeared for 1000 ms. In some trials, one of the bars had rotated by 90 deg when it reappeared. The animal had to make a saccade to this bar within 600 ms to be rewarded. In the remaining trials, no bar was rotated and the animal was rewarded for maintaining fixation. The behavioral performance was recorded in terms of the percentage of correct responses. On microstimulation trials, an 80 ms burst of 200 μA peak-to-peak biphasic pulses at 200 Hz was injected into LIP, 250 ms after the first presentation of the bars was extinguished. Both animals showed a decrease in performance on microstimulation trials when the rotation occurred inside the RF. On the contrary, no effect of microstimulation was found when no bar rotated or when the rotation occurred at the opposite location. These results suggest that the microstimulation of LIP disrupts the priority map at the location being stimulated, but does not effect the allocation of attention at other locations.
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