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Michael S Bendiksby, Michael L Platt; Effects of attention and motivation on neuronal activity in parietal cortex. Journal of Vision 2003;3(9):475. doi: https://doi.org/10.1167/3.9.475.
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Prior studies have demonstrated that neuronal activity in the lateral intraparietal area (LIP) is correlated with the probability or magnitude of reward that can be expected upon execution of visually-guided saccades as well as by the deployment of visual attention. Reward-related modulations in neuronal activity may thus reflect differential deployment of attention to visual stimuli based on reward size or certainty. The goal of this study was to distinguish motivational from attentional representations in LIP. To accomplish this, rhesus monkeys were trained to perform a peripheral attention task at psychophysical threshold. Subjects were required to indicate the brief flicker of one of two peripheral cues by shifting gaze to a response target positioned in the opposite hemifield. On each trial, one randomly selected peripheral cue was illuminated first, indicating the location of the flicker with 80% validity. The magnitude of reward delivered for correct trials was then varied independently across blocks. Flicker detection was correlated with cue validity, indicating that subjects selectively attended to the early onset location. Blocks of larger reward were associated with shorter reaction times on both valid and invalid trials, indicating a general increase in motivation. Elevated motivation was associated with increases in the signal detection measure d′, indicating enhanced visual processing at the attended location. Neuronal activity in LIP was higher for the attended location, and increased reward was associated with enhanced neuronal selectivity. These data suggest that neuronal activity in LIP reflects the differential deployment of attention to visual stimuli, and that motivation sharpens attentional processing.
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