Evidence for hierarchical error processing in the human brain

Human goal-directed behavior depends on multiple neural systems that monitor and correct for different types of errors. For example, tracking errors in continuous motor tasks appear to be processed by a system involving posterior parietal cortex, whereas errors in speeded response and trial-and-error learning tasks appear to be processed by a system involving frontal-medial cortex. To date, it is unknown whether there is a functional relationship between the posterior and frontal error systems. We recorded the event-related brain potential from participants engaged in a tracking task to investigate the role of the frontal system in continuous motor control. Our results demonstrate that tracking errors elicit temporally distinct error-related event-related brain potentials over frontal and posterior regions of the scalp, suggesting an interaction between the subcomponents of a hierarchically organized system for error processing. Specifically, we propose that the frontal error system assesses high-level errors (i.e. goal attainment) whereas the posterior error system is responsible for evaluating low-level errors (i.e. trajectory deviations during motor control).