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Home | Seminars and Symposia | Past seminars/symposia: Friday, October 30, 2015

DTC Seminar Series

Making choices and selecting actions: How your brain decides in a dynamic world

by

Vasileios Christopoulos
The Andersen Lab
California Institute of Technology

Friday, October 30, 2015
12:45 p.m. reception
1:00 p.m. seminar

401/402 Walter Library

Decision-making is a vital component of human and animal behavior that involves selecting between alternative options and generating actions to implement the choices. While simple decisions involve choosing a goal and pursuing it, humans and animals evolved to survive in hostile dynamic environments where goal availability and value can change with time and previous actions, entangling goal decisions with action selection. A predator chasing multiple prey exemplifies how goals can dynamically change and compete during ongoing actions. Classical economic theories posit that decision-making takes place within frontal brain areas and is a separate process from the neural systems for perception and action. Critically, action-planning and actionexecution begin only after a decision is made. However, recent experimental studies challenged this long-held theory arguing that decisions that involve immediate physical actions emerge via a continuous competition between internal representations of the potential actions. According to these studies, when deciding which of several possible actions to perform, the brain generates multiple competing actions simultaneously and uses online information to bias the competition until a single action is executed. In large part this theory is based on evidence from neurophysiological studies in animals. Evidence includes the formation of potential actions prior to decision and the coding of decision variables, such expected reward and outcome probability, by cortical regions that have traditionally associated with planning and execution of actions. However, it has been argued that these findings are not necessarily related to the decision process, but instead they are related to the sensory properties of the alternative options.

Overall, these findings have created a considerable uncertainty regarding the underlying mechanisms by which the brain selects between competing actions. I will discuss recent human and animal studies in our lab showing that decisions that involve immediate physical actions cannot be modeled within the traditional serial model. Instead, they are consistent with the idea that decisions emerge via a continuous competition between multiple actions. I will present two computational models that we recently proposed to model decisions between competing options. Finally, I will discuss how our findings can provide a conceptual alternative in understanding important aspects of neurological disorders that cause deficits in choice behavior, such as the hemispatial neglect and the extinction syndrome.