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Medha Shekhar, Dobromir Rahnev; Distinguishing the roles of dorsolateral and anterior PFC in visual metacognition. Journal of Vision 2018;18(10):665. doi: https://doi.org/10.1167/18.10.665.
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Visual metacognition depends on regions within the prefrontal cortex. Two areas in particular have been repeatedly implicated: the dorsolateral prefrontal cortex (DLPFC) and the anterior prefrontal cortex (aPFC). However, it is still unclear what the function of each of these areas is and how they differ from each other. To establish the specific roles of DLPFC and aPFC in metacognition, we employed online transcranial magnetic stimulation (TMS) to causally interfere with their functioning during metacognitive computations. Subjects (N = 21) performed a visual discrimination task while providing confidence ratings. We delivered TMS on each trial to one of the following three sites: DLPFC, aPFC and the somatosensory cortex (S1; control site). We found a clear dissociation between the effects of TMS on the two prefrontal areas: DLPFC TMS lowered mean confidence ratings (mean difference with S1 TMS = -0.09, P = 0.006), whereas aPFC TMS increased metacognitive ability but only for the second half of the experimental blocks (mean difference with S1 = 0.22, P = 0.03). These results support a functional architecture where DLPFC extracts the strength of the sensory evidence and sends it to aPFC, which generates the actual confidence rating by potentially incorporating additional, non-perceptual information. Further, we simulated a hierarchical confidence generation model that incorporates these putative DLPFC and aPFC functions. Specifically, we modeled DLPFC TMS as a decrease in the sensory signal that is input to the metacognitive level and aPFC TMS as a decrease in the noise that corrupts the confidence signal. The simulations reproduced our behavioral results thus corroborating the proposed roles of DLPFC and aPFC in metacognitive computation. Our findings causally establish DLPFC and aPFC as distinct nodes in a metacognitive network and suggest specific contributions for each of these regions to confidence generation.
Meeting abstract presented at VSS 2018
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