Background: Our previous work described the neural processes of motor response inhibition during a stop signal task (SST). Employing the race model, we computed the stop signal reaction time (SSRT) to index individuals' ability in inhibitory control. The pre-supplementary motor area (preSMA), which shows greater activity in individuals with short as compared to those with long SSRT, plays a role in mediating response inhibition. In contrast, the right inferior prefrontal cortex (rIFC) showed greater activity during stop success as compared to stop error. Here we further pursued this functional differentiation of preSMA and rIFC on the basis of an intra-subject approach.

The ability to detect errors and adjust behavior accordingly is essential for maneuvering in an uncertain environment. Errors are particularly prone to occur when multiple, conflicting responses are registered in a situation that requires flexible behavioral outputs. Previous studies have provided evidence indicating the importance of the medial cortical brain regions including the cingulate cortex in processing conflicting information. However, conflicting situations can be successfully resolved, or lead to errors, prompting a behavioral change in the observers. In particular, how does the brain use error signals specifically to adjust behavior on the fly? Here we employ a stop signal task (SST) to elicit errors approximately half of the time in high-conflict trials despite constant behavioral adjustment of the observers. Using functional magnetic resonance imaging, we show greater and, sequentially, less activation in the medial cortical regions when observers made an error, compared to when they successfully resolved high-conflict responses. Errors also evoked greater activity in the cuneus, retrosplenial cortex, insula, and subcortical structures including the thalamus and the region of the epithalamus (the habenula). We further showed that the error-related medial cortical activities are not correlated with post-error behavioral adjustment, as indexed by post-error slowing (PES) in go trial reaction time. These results delineate an error-specific pattern of brain activation during the SST. The results also suggest that the relationship between error-related activity and post-error behavioral adjustment may be more complicated than has been conceptualized by the conflict monitoring hypothesis.

The locus coeruleus (LC) provides the primary noradrenergic inputs to the cerebral cortex. Despite numerous animal studies documenting the functions of the LC, research in humans is hampered by the small volume of this midbrain nucleus. Here, we took advantage of a probabilistic template, explored the cerebral functional connectivity of the LC with resting-state fMRI data of 250 healthy adults, and verified the findings by accounting for physiological noise in another data set. In addition, we contrasted connectivities of the LC and the ventral tegmental area/substantia nigra pars compacta. The results highlighted both shared and distinct connectivity of these 2 midbrain structures, as well as an opposite pattern of connectivity to bilateral amygdala, pulvinar, and right anterior insula. Additionally, LC connectivity to the fronto-parietal cortex and the cerebellum increases with age and connectivity to the visual cortex decreases with age. These findings may facilitate studies of the role of the LC in arousal, saliency responses and cognitive motor control and in the behavioral and cognitive manifestations during healthy and disordered aging. Although the first to demonstrate whole-brain LC connectivity, these findings need to be confirmed with high-resolution imaging.