Funded Grants

A stopping circuit for human self control

How do people control inappropriate actions, thoughts, motivations and urges? Such self-control can be achieved by many different strategies including changing one’s environment, thinking about things differently, redirecting one’s attention, and, as a last recourse, stopping the action, and perhaps the cognition or motivation from being expressed. Of these, stopping action is the most tractable for cognitive neuroscience research. An example of stopping action is your cancellation of impending movement when you are about to step into the street and suddenly notice a car bearing down. My research program has investigated this kind of action stopping in detail, and has identified a core brain circuit. Now I plan to radically extend this research program by asking whether this same stopping circuit also underlies the control of thoughts, motivations and urges.

Beyond actions, stopping also affects thought. One way this happens is analogous to the experience of having a conversation interrupted by a surprising event, resulting in a loss of one’s “train of thought.” In effect, the surprising event recruits the brain’s stopping circuit and massively suppresses current cortical contents. Motorically, this is the ‘jolt’ that can accompany rapid movement cancellation; cognitively, this might actually erase the current goals. As the modern world contains many irrelevant and surprising stimuli, this research tack offers a compelling window into better understanding everyday distractibility.

Most of us want to control excessive motivations towards things such as cookies, alcohol, or smartphones. But can stopping even be directed at the value of the stimulus rather than the motor tendency per se? One intriguing possibility, suggested by our recent work, is that if people repeatedly practice stopping actions toward such stimuli they can reduce their associated value. This could subsequently diminish the motivating impact of a stimulus. Better understanding this effect would have profound implications for behavior modification, especially for disorders such as gambling and substance abuse.

These examples all activate the stopping circuit rapidly. But can it also be activated in an extended fashion, i.e. over seconds and minutes? I hypothesize that it can, and that this is crucial to what makes something an urge. One interesting thing about urges is that they have an inherent element of restraint. Showing that this restraint relates to the stopping circuit would provide a neural-mechanistic understanding of urges for the first time.

Testing these ideas involves developing new behavioral paradigms, and using methods that can measure the stopping circuit of the brain, as well as stimulation methods that can prove that the stopping circuit is causally important for diverse aspects of human self control well beyond merely stopping action.