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Is the Sub-cortical Colliculus Slave or Master during Value-based Orienting?


There is a dominant view that value-based decision-making occurs predominantly within a fronto-parietal cortical network. Once a decision has been reached, a command is then routed to the appropriate pre-motor region that faithfully enacts the desired action (e.g., eye, hand, etc. movement). Here we examine whether the sub-cortical superior colliculus is actively involved in making value-based decisions or it is simply a post-decisional motor structure. Monkeys performed a saccade foraging task in which they maximized their reward intake by choosing visual targets in descending order of their economic value. Neuronal activity was strongly correlated to both the value of available alternatives and upcoming choices. To test whether this activity was actively involved in the decision process we perturbed collicular activity with very low levels of electrical microstimulation. Choices became biased towards the stimulation site in a manner lawfully predicted by economic models. Our results suggest that even sub-cortical motor structures actively participate in the decision-making process.


Mike Dorris was born and raised in Trenton, Ont. He obtained his B.Sc. in Life Sciences at Queen’s (1993), and then completed his M.Sc. (1995) and Ph.D. (2000) with Doug Munoz in the Department of Physiology. His graduate research launched a life-long interest in the role of pre-motor neural circuits in behavioural control. Specifically, his research examines how the brain chooses between and efficiently prepares actions, when we are faced with uncertainty. Dr. Dorris received the Governor General Gold Medal for his Ph.D. thesis. He then moved to New York University for his post-doctoral studies with Paul Glimcher. His pioneering work in Neuroeconomics examined the role of the parietal cortex in decision making during strategic games. In the Fall of 2003, Dr. Dorris joined the Department of Physiology at Queen’s as an assistant professor and recipient of a Tier II Canada Research Chair in Neural Control of Decision Making. Dr. Dorris was promoted to Associate Professor in 2009. In 2013, Dr. Dorris moved his laboratory to the Institute of Neuroscience within the Shanghai Institutes of Biological Sciences where he is Head Investigator of the Laboratory of Decision-Making. He continues to focus on elucidating brain areas involved in choosing motor actions based on their economic value.

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