Metacognition as the capacity of monitoring one's own cognition operates across domains.Here, we addressed whether metacognition in different cognitive domains rely on common or distinct neural substrates with diffusion tensor imaging (DTI) and inter-areal functional connectivity techniques. After acquiring DTI and resting-state fMRI data, we asked participants to perform a temporal-order memory judgement task and a perceptual discrimination task, followed by trial-specific confidence judgments. DTI analysis revealed that the structural integrity (fractional anisotropy) in the anterior portion of right superior longitudinal fasciculus (SLF) was associated with both perceptual and mnemonic metacognitive abilities. When the mnemonic metacognitive ability was disrupted by TMS, the mnemonic metacognition scores did not correlate with SLF structural integrity anymore, revealing the causal relevance of this tract in memory metacognition. Furthermore, taking the dorsolateral PFC and IPL (both of which are connected by SLF) as seeds, we found perceptual and mnemonic metacognitive abilities to be associated with functional connectivity between DLPFC and VLPFC, whereas mnemonic metacognitive ability was selectively associated with connectivity between IPL and precuneus. These results illustrate the importance of SLF and a distinct white-matter grey-matter circuitry that supports human metacognition.
Introduction:The capacity of reflecting on one's own cognitive process is known as metacognition (Flavell, 1979;Fleming and Dolan, 2012;Yeung and Summerfield, 2012). Metacognition has been considered as the most crucial function emerged during evolution (Hayes, 2016). Given its crucial functions, researchers have endeavored to understand how a metacognitive judgment is computed (Fleming and Daw, 2017;Kepecs et al., 2008;Zylberberg et al., 2016), how it is disrupted in psychiatric disorders (Hauser et al., 2017a;Rouault et al., 2018a), and how its accuracy can be improved (Carpenter et al., 2019). Metacognition is an umbrella term for the higher-level cognition about the lower-level cognition in various domains (e.g., perception and memory). As cognitive processes are implemented in the brain, an interesting and important question is whether the neural circuit supporting metacognition is the same or distinct across different cognitive domains.A large body of fMRI work have increasingly demonstrated a nuanced picture for this domaingenerality issue of metacognition. For example, the dorsolateral prefrontal cortex (DLPFC) might be involved in reading out the information of primary decision-making and using it for computing both perceptual and mnemonic metacognitive judgements (Chua and Ahmed, 2016;Fleming and Dolan, 2012;Kwok et al., 2019;Rounis et al., 2010). Morales et al. (2018) reported that the dorsal anterior cingulate cortex (dACC) was active during metacognitive evaluation in both memory and perception tasks but also found the activation patterns decoded from a perception task in the posterior medial frontal cortex and ven...