Abstract
It is now well established that activity in sensory systems is subject to cross-modal attention. Attending to a stimulus in one sensory modality enhances activity in that sensory system, but simultaneously suppresses activity in other sensory systems. Here, we determined whether such cross-modal attention affects activity in the vestibular system. To this end, we employed a visual multiple object tracking task. We varied the number of tracked targets to measure the effect of attentional load on vestibular (parieto-insular vestibular cortex: PIVC) and visual-vestibular (posterior insular cortex: PIC) areas, while holding perceptual load constant. Participants performed the tracking task during functional magnetic resonance imaging (fMRI). Compared to passive viewing of multiple-object motion, activity during object tracking was increased in visual area MT+, posterior parietal cortex (PPC) and the frontal eye fields (FEF) in a load-dependent manner (replicating eariler results, Culham et al., 2001, Neuron, 32, 737–745). At the same time, activity in PIVC was suppressed and this suppression of activity increased with increasing attentional load. A similar load-dependent effect was evident in the anterior part of PIC, such that activity decreased with greater loads, whereas it was absent in posterior PIC. These results suggest that attention has a cross-modal modulatory effect on vestibular cortex during visual object tracking. Further results of a control experiment show that most of the suppression in PIVC is not caused by the visual stimulus per se, but by attention to the visual stimulus, suggesting that inhibitory interactions between sensory systems might not be hard-wired, but flexible, and depend on the allocation of attention to a particular sensory domain.
Meeting abstract presented at VSS 2017