Feature-Based Attention Affects Direction-Selective fMRI Adaptation in hMT+

Abstract

Functional magnetic resonance adaptation has been successfully used to reveal direction-selective responses in the human motion complex (hMT+). Here, we aimed at further investigating direction-selective as well as position-selective responses of hMT+ by looking at how these responses are affected by feature-based attention. We varied motion direction and position of 2 consecutive random-dot stimuli. Participants had to either attend to the direction or the position of the stimuli in separate runs. We show that direction selectivity in hMT+ as measured by functional magnetic resonance imaging (fMRI) adaptation was strongly influenced by task set. Attending to the motion direction of the stimuli lead to stronger direction-selective fMRI adaptation than attending to their position. Position selectivity, on the other hand, was largely unaffected by attentional focus. Interestingly, the change in the direction-selective adaptation profile across tasks could not be explained by inheritance from earlier areas. The response pattern in the early retinotopic cortex was stable across conditions. In conclusion, our results provide further evidence for the flexible coding of direction information in hMT+ depending on task demands.