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Michele Basso; A role for the superior colliculus in decision-making and confidence. Journal of Vision 2017;17(10):1390. doi: 10.1167/17.10.1390.
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Evidence implicates the superior colliculus (SC) in attention and perceptual decision-making. In a simple target-selection task, we previously showed that discriminability between target and distractor neuronal activity in the SC correlated with decision accuracy, consistent with the hypothesis that SC encodes a decision variable. Here we extend these results to determine whether SC also correlates with decision criterion and confidence. Trained monkeys performed a simple perceptual decision task in two conditions to induce behavioral response bias (criterion shift): (1) the probability of two perceptual stimuli was equal, and (2) the probability of one perceptual stimulus was higher than the other. We observed consistent changes in behavioral response bias (shifts in decision criterion) that were directly correlated with SC neuronal activity. Furthermore, electrical stimulation of SC mimicked the effect of stimulus probability manipulations, demonstrating that SC correlates with and is causally involved in setting decision criteria. To assess confidence, monkeys were offered a 'safe bet' option on 50% of trials in a similar task. The 'safe bet' always yielded a small reward, encouraging monkeys to select the 'safe bet' when they were less confident rather than risk no reward for a wrong decision. Both monkeys showed metacognitive sensitivity: they chose the 'safe bet' more on more difficult trials. Single- and multi-neuron recordings from SC revealed two distinct neuronal populations: one that discharged more robustly for more confident trials, and one that did so for less confident trials. Together these finding show how SC encodes information about decisions and decisional confidence.
Meeting abstract presented at VSS 2017
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