29 novembre 2012: Prof. Wolfram Schultz
Thursday, November 29th 2012, 12h30
Prof. Wolfram SCHULTZ
Wellcome Principal Research Fellow
Professor of Neuroscience
Department of Physiology, Development and Neuroscience
University of Cambridge, UK
"Neuronal reward and risk signals "
We investigate basic neuronal reward and risk processes that are important for decision making, using neurophysiological and neuroimaging methods. Dopamine neurons are activated by rewards and reward prediction stimuli. The signal reflects reward prediction error which represents a crucial signal for learning. As electrical and optogenetic activation of dopamine neurons elicits learning and approach behaviour, the data suggest a role for dopamine neurons in reward processing. Reward value appears to depend on the individual decision maker and the environment, and hence it is subjective. Dopamine neurons discount reward value across temporal delays of a few seconds, suggesting subjective value coding. Reward predictions inform about probability distributions of reward value. Dopamine and orbitofrontal neurons code value distinct from risk. Risk processing depends on individual risk attitude in humans. These data suggest that reward neurons code subjective reward value underlying economic decisions.
Wolfram Schultz is interested to relate the mechanics of brain activity to measurable behaviour. He combines behavioural, neurophysiological and neuroimaging techniques to investigate the neural mechanisms of learning, goal-directed behaviour and economic decision making at the level of single neurons and individual brain structures. He uses behavioural concepts from animal learning theory and economic decision theories to study the neurophysiology and neuroimaging of reward and risk in individual neurons and in specific brain regions, including the dopamine system, striatum, orbitofrontal cortex and amygdala. Wolfram Schultz discovered the phasic reward signal of dopamine neurons and characterised its coding of reward prediction error. He also imaged the first human brain reward signal with Nico Leenders. His current interests are in adaptive and reference dependent coding of reward value (a corner stone of Prospect Theory), neuronal risk signals for reward, and the influence of risk on reward value (as predicted by Utility Theory). These studies help to kindle the current interest of the experimental and theoretical neuroscience community in reinforcement learning and neuroeconomics and led to a large number of reward and economic decision studies in humans and animals. Wolfram Schultz received a doctoral degree in medicine from the University of Heidelberg, Germany, and a 'habilitation' at the University of Fribourg, Switzerland. He was a postdoctoral fellow at the Max-Planck Institute for Biophysical Chemistry in Göttingen, SUNY Buffalo and Karolinska Institute, Stockholm, before taking up junior and senior faculty positions at the University of Fribourg. In 2001 he moved to the University of Cambridge. He was a visiting scientist at Tokyo Metropolitan Institute for Neuroscience and at Tamagawa University and is a Visiting Research Associate at Caltech, Pasadena. A Fellow of the Royal Society, Wolfram Schultz has been awarded the 1984 Ellerman Prize of the Swiss Societies of Neurology, Neurosurgery and Neuropatholgy, the 1997 Theodore-Ott Prize of the Swiss Academy of Medical Sciences (shared), the 2002 Golden Brain Award of the Minerva Foundation, San Francisco, the 2005 Ipsen Prize for Neuronal Plasticity (shared) and the 2010 FENS-EJN Award. Wolfram Schultz is a past president of the European Brain and Behaviour Society and has served on national and international scientific councils and committees.