Task effects reveal flexible coding in the human motion complex (hMT+)
Weigelt, S.1,2, Singer, W.1,2, and Kohler, A.1,2
1Max-Planck-Institut für Hirnforschung, Frankfurt; 2Brain Imaging Center, Frankfurt
Using functional magnetic resonance (fMRI) we addressed two questions with regard to motion processing in the human motion complex (hMT+): Is fMRI adaptation in hMT+ influenced by the behavioral task? Is direction-selective fMRI adaptation in hMT+ fully inherited from primary visual cortex (V1)? Focusing on the interaction of position- and direction-selective fMRI adaptation we scanned 20 subjects that performed two behavioral tasks. Our results show that fMRI adaptation in hMT+ is strongly influenced by the behavioral task. When subjects perform a task on motion direction, the response profile of hMT+ displays an interaction of position- and direction-selective adaptation. This response profile cannot be easily explained by a mere inheritance from V1 (that displays a pure position-selective adaptation effect). When subjects perform the position task, hMT+ (as well as V1) shows a pure position-selective adaptation effect. We conclude that task set fundamentally changes adaptive processes in hMT+ allowing for flexible coding.