will take place on Tuesday, 31 January 2017 from 17:15 to 18:15 hours in CBBM Research Building, EG, Room 50/51.
Host: Prof. Thomas Münte
Department of Neurology
University of Lübeck
Abstract
We make thousands of choices each day. Even the simplest of these choices result from a complex interplay of large numbers of neurons that are distributed across multiple brain regions. I will present recent work from my lab that aims to uncover how this interplay is dynamically shaped by global brain states. I will focus on a pervasive feature of choice behavior: variations in choice across repeated presentations of the same choice options. Most existing computational models of decision-making account for this choice variability by introducing random ‘noise’ into the decision process. Other models postulate that choice variability reflects hidden, but systematic, biases in the decision process. I will present converging evidence that helps reconcile these ideas. In a number of experiments, we monitor subjects’ behavior together with central arousal state (assessed through pupil diameter) and neural population activity (assessed through fMRI and MEG) during elementary sensory-motor decisions. This reveals that a substantial component of choice variability is explained by trial-to-trial fluctuations in central arousal: Phasic boosts of arousal during decision formation predict a systematic reduction in subjects’ intrinsic decision biases. Brainstem fMRI shows that the decision-related arousal boost reflects evoked responses in a network of neuromodulatory brainstem systems controlling central arousal state, including the noradrenergic system. Further, we find that the effect of the decision-related arousal boost on bias is mediated by a selective modulation of choice-encoding pattern signals in frontal and parietal association cortex. Taken together, our results suggest that the phasic release of neuromodulators during decision-making dynamically suppresses preexisting biases in the brain’s decision-making machinery. Without monitoring central arousal state, the resulting variations in decision bias appear as random behavioral noise.
Biosketch
Tobias Donner is a Full Professor of Integrative Neuroscience at the University Medical Center Hamburg-Eppendorf (UKE). His lab studies the interaction between brain states and the neural computations underlying decisions. To this end, the lab combines quantitative analysis of behavior, computational modeling, multimodal neuroimaging (fMRI and MEG), and pharmacological interventions. In 2003, Tobias Donner earned an MD from the Charitè, Berlin, and completed his doctoral work at the Berlin Neuroimaging Centre (with Arno Villringer and Stephan Brandt). From 2003 to 2006, he was on a joint postdoc position at the Dept of Neurophysiology, UKE, and the Donders Institute in Nijmegen (with Andreas Engel and Pascal Fries). From 2006 to 2009, he joined David Heeger’s Computational Neuroimaging Lab at New York University on a Postdoctoral Fellowship award of the German National Academy of Sciences Leopoldina. In 2009, became Assistant Professor in Brain and Cognition at the University of Amsterdam. Since 2015, he is full Professor at the UKE, funded by a Heisenberg-Professorship of the DFG.
