MS Defense by Medha Shekhar

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Name: Medha Shekhar

Master’s Thesis Defense Meeting
Date: Friday, April 20th, 2018
Time: 11:00am
Location: J.S. Coon Building, room 150
Professor Dobromir Rahnev, Ph.D. (Georgia Tech)
Thesis Committee Members:
Professor Dobromir Rahnev, Ph.D. (Georgia Tech)
Professor Eric Schumacher, Ph.D. (Georgia Tech)

Professor Christopher Hertzog, Ph.D. (Georgia Tech)
Title: Distinguishing the roles of dorsolateral and anterior PFC in visual metacognition



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 confidence generation. Human subjects from both sexes performed a perceptual decision-making task and provided confidence ratings. We found a clear dissociation between the two areas: DLPFC TMS lowered confidence ratings, whereas aPFC TMS increased metacognitive ability but only for the second half of the experimental blocks. These results support a functional architecture where DLPFC reads out the strength of the sensory evidence and relays it to aPFC, which makes the confidence judgement by potentially incorporating additional, non-perceptual information. Indeed, simulations from a model that incorporates these putative DLPFC and aPFC functions reproduced our behavioral results. These findings establish DLPFC and aPFC as distinct nodes in a metacognitive network and suggest specific contributions from each of these regions to confidence generation.


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