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Sensitivity Derivatives for Flexible Sensorimotor Learning

mohamed.abdelghani{at}utoronto.ca Department of Physiology, University of Toronto, Toronto, Ontario, Canada

T. P. Lillicrap

tim{at}biomed.queensu.ca Centre for Neuroscience Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada

D. B. Tweed

douglas.tweed{at}utoronto.ca Departments of Physiology and Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada, and Centre for Vision Research, York University, Toronto, Ontario M3J 1P3, Canada

To learn effectively, an adaptive controller needs to know its sensitivity derivatives—the variables that quantify how system performance depends on the commands from the controller. In the case of biological sensorimotor control, no one has explained how those derivatives themselves might be learned, and some authors suggest they are not learned at all but are known innately. Here we show that this knowledge cannot be solely innate, given the adaptive flexibility of neural systems. And we show how it could be learned using forms of information transport that are available in the brain. The mechanism, which we call implicit supervision, helps explain the flexibility and speed of sensorimotor learning and our ability to cope with high-dimensional work spaces and tools.