NEURONAL BASIS OF PERSISTENCE

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Abstract Traditional approaches to understanding the neural bases of choice and control involve discrete choice tasks. In these tasks, decision-makers make categorical decisions at a single point in time. While such tasks have led to invaluable insights, they are poorly suited to shed light on one of the key elements of natural decisions, their continuous nature. Continuous decisions are especially interesting as a laboratory tool for studying the neural basis of persistence, which is a key ingredient of drug abstinence and which is difficult to capture with discrete decision-making tasks. Understanding the neural basis of continuous decisions is critical for developing an understanding of the neural circuitry of decision-making. Using discrete choice tasks, neuroscience has made great strides in understanding choice and control, and has begun to pin down the role of a key brain structure, the dorsal anterior cingulate cortex (dACC). Activity of single neurons in this region encodes multiple variables associated with aspects of discrete decisions and also with monitoring the outcomes of those decisions and adjusting behavior appropriately afterward. Aberrant activity in the dACC is also associated with the progression of diseases associated with poor self-control and persistence, such as addiction. These facts suggest strongly that the dACC plays a pivotal role in continuous decisions as well. Our central hypothesis is that both monitoring and decision processes in continuous decision-making are implemented, at least in part, by dACC. One critical barrier to studying continuous decisions is the lack of readily usable laboratory tasks that are trainable in model animals, reliably performable for hundreds of trials, that elicit persistence, and that motivate continuous adjustment. Our lab has recently developed a guided pursuit task for rhesus macaques. In this task, subjects use a joystick to control an avatar on a computer screen. Using this avatar, they pursue virtual fleeing prey and avoid pursuing predators (in other words, it is a kind of simplified Pac-man). Our proposed research program will answer the following key questions: How does the dACC track movements of agents in guided pursuit? What are the behavioral and neural bases of future state prediction in guided pursuit? What are the neural bases of changes of mind in continuous decisions?