Distinguishing the Roles of Dorsolateral and Anterior PFC in Visual Metacognition

Abstract

Visual metacognition depends on regions within the prefrontal cortex (PFC). Two areas in particular have been implicated repeatedly: the dorsolateral PFC (DLPFC) and the anterior PFC (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 used online transcranial magnetic stimulation (TMS) to interfere causally with their functioning during confidence generation. Human subjects from both sexes performed a perceptual decision making 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 in which DLPFC reads out the strength of the sensory evidence and relays it to aPFC, which makes the confidence judgment by potentially incorporating additional, nonperceptual 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. The prefrontal cortex (PFC) is known to be critical for metacognition. Two of its subregions, the dorsolateral PFC (DLPFC) and the anterior PFC (aPFC), have been specifically implicated in confidence generation. However, it is unclear whether these regions have distinct functions related to the underlying metacognitive computation. Using a causal intervention with transcranial magnetic stimulation, we demonstrate that DLPFC and aPFC have dissociable contributions: targeting DLPFC decreased average confidence ratings, whereas targeting aPFC affected metacognitive scores specifically. Based on these results, we postulated specific functions for DLPFC and aPFC in metacognitive computation and corroborated them using a computational model that reproduced our results. Our causal results reveal the existence of a specialized modular organization in PFC for confidence generation.

Private–public mappings in human prefrontal cortex

“…For example, a recent fMRI study found that pgACC tracked all variables necessary for the formation of an internal sense of confidence in a novel psychophysical task that isolates decision confidence from its component parts ( Bang and Fleming, 2018 ). Second, FPl, a region in human prefrontal cortex with no homologue in the monkey brain ( Neubert et al, 2014 ), has consistently been found to track explicit (public) reports of confidence ( Bang and Fleming, 2018 ; Fleming et al, 2012 ; Fleming et al, 2018 ; Gherman and Philiastides, 2018 ; Hilgenstock et al, 2014 ; Shekhar and Rahnev, 2018 ; Yokoyama et al, 2010 ). Of the three ROIs, FPl is of particular interest.…”

“…First, recent work has indicated that dorsal anterior cingulate cortex (dACC) ( Fleming et al, 2012 ; Fleming et al, 2018 ) and perigenual anterior cingulate cortex (pgACC) ( Bang and Fleming, 2018 ; De Martino et al, 2013 ; Gherman and Philiastides, 2018 ; Lebreton et al, 2015 ; Wittmann et al, 2016 ) – both located in the medial wall of PFC – support the formation of an internal (private) sense of confidence. Second, a large body of literature has observed activation of lateral PFC, in particular the lateral frontal pole (FPl), in relation to explicit (public) reports of confidence ( Bang and Fleming, 2018 ; De Martino et al, 2013 ; Fleming et al, 2012 ; Fleming et al, 2018 ; Gherman and Philiastides, 2018 ; Hilgenstock et al, 2014 ; Shekhar and Rahnev, 2018 ; Yokoyama et al, 2010 ) – raising the possibility that lateral PFC supports a mapping between private and public confidence. This hypothesis fits with a broader role of lateral PFC in cognitive control functions such as task or set switching ( Badre, 2008 ; Badre and Nee, 2018 ).…”

Unconscious reinforcement learning of hidden brain states supported by confidence

“…In the present task confidence judgments happened earlier in time than action selection, forcing its explicit computation early onthis could have then been used to inform RL state search. A compelling addition to this argument is that subjects whose decoder was based in PFC, a strong candidate as metacognitive substrate 16,32,58 , also displayed larger effect sizes in confidence-RL correlation measures (Figs. 4a and 5a, b).…”

Focal optogenetic suppression in macaque area MT biases direction discrimination and decision confidence, but only transiently

“…It would be of interest to deploy manipulations that alter the correspondence between choice and confidence to a greater degree than what we observed here, while recording simultaneously from sensory and higher order areas. Recent studies in humans point toward several frontal lobe structures involved in generating and reporting the sense of confidence ( Bang and Fleming, 2018 ; Fleming et al, 2015 ; Morales et al, 2018 ; Shekhar and Rahnev, 2018 ). Little is known about where and how such computations occur in the nonhuman primate brain, although the supplementary eye field seems to play a role ( Middlebrooks and Sommer, 2012 ; So and Stuphorn, 2016 ).…”