Neuroanatomical correlates of self-awareness of highly practiced visuomotor skills.

Metacognition is the ability to introspect and control ongoing cognitive processes. Despite the extensive investigation of the brain architectures supporting metacognition for perception and memory, little is known about the neural basis of metacognitive capacity for motor function, a vital aspect of human behavior. Here, using functional and structural magnetic resonance imaging (MRI), we examined the brain substrates underlying self-awareness of handwriting, a highly practiced visuomotor skill. Results showed that experienced adult writers generally overestimated their handwriting quality, and such overestimation was more pronounced in men relative to women. Individual variations in self-awareness of handwriting quality were positively correlated with gray matter volume in the left fusiform gyrus, right middle frontal gyrus and right precuneus. The left fusiform gyrus and right middle frontal gyrus are thought to represent domain-specific brain mechanisms for handwriting self-awareness, while the right precuneus that has been reported in other domains likely represents a domain-general brain mechanism for metacognition. Furthermore, the activity of these structurally related regions in a handwriting task was not correlated with self-awareness of handwriting, suggesting the correlation with metacognition was independent of task performance. Together, this study reveals that metacognition for practiced motor skills relies on both domain-general and domain-specific brain systems, extending our understanding about the neural basis of human metacognition.