The neural mechanisms of real-time decisions

Psychological and neurophysiological studies of decision-making have focused primarily on scenarios in which subjects are faced with abstract choices that are stable in time. This has led to serial models which begin with the representation of relevant information about costs and benefits, followed by careful deliberation about the choice, followed by action planning and execution. However, the brain evolved to interact with a dynamic and constantly changing world, in which the choices themselves as well as their relative costs and benefits are defined by the momentary geometry of the immediate environment and are continuously changing during ongoing activity. To deal with the demands of real-time interactive behavior, animals require a neural architecture in which the sensorimotor specification of potential actions, their valuation, selection, and even execution can all take place in parallel. I will describe a general hypothesis for how the brain deals with the challenges of such dynamic and embodied behavior, and present the results of a series of behavioral and neurophysiological experiments in which humans and monkeys make decisions on the basis of sensory information that changes over time. These experiments suggest that sensory information pertinent to decisions is processed quickly and combined with a growing signal related to the urge to act, and the result biases a competition between potential actions that takes place within the same sensorimotor circuits that guide action.

Paul Cisek is a full professor in the Department of Neuroscience at the University of Montreal. He has a background in computer science and artificial intelligence, doctoral training in computational neuroscience with Stephen Grossberg and Daniel Bullock, and postdoctoral training in neurophysiological recording in non-human primates with Stephen Scott and John Kalaska. His work combines these techniques into an interdisciplinary approach to understanding how the brain controls our interactions with the world. In particular, his theoretical work suggests that the brain is organized as a system of parallel sensorimotor streams that have been differentiated and elaborated over millions of years of evolution, and his empirical work investigates the neural dynamics of how potential actions are specified and how they compete in the cortical and subcortical circuits of humans and other primates.