title: Re-examining overlap between tactile and visual motion responses within hMT+ and STS.
abstract: Here, we examine overlap between tactile and visual motion BOLD responses within the human MT+ complex. Although several studies have reported tactile responses overlapping with hMT+, many used group average analyses, leaving it unclear whether these responses were restricted to subregions of hMT+. Moreover, previous studies either employed a tactile task or passive stimulation, leaving it unclear whether or not tactile responses in hMT+ are simply the consequence of visual imagery. Here, we carried out a replication of one of the classic papers finding tactile responses in hMT+. We mapped MT and MST in individual subjects using visual field localizers. We then examined responses to tactile motion on the arm, either presented passively or in the presence of a visual task performed at fixation designed to minimize visualization of the concurrent tactile stimulation. To our surprise, without a visual task, we found only weak tactile motion responses in MT (6% of voxels showing tactile responses) and MST (2% of voxels). With an unrelated visual task designed to withdraw attention from the tactile modality, responses in MST were reduced to almost nothing (<1% regions). Consistent with previous results, we did observe tactile responses in STS regions superior and anterior to hMT+. Despite the lack of individual overlap, group-averaged responses produced strong spurious overlap between tactile and visual motion responses within hMT+ that resembled those observed in previous studies. The weak nature of tactile responses in hMT+ (and their abolition by withdrawal of attention) suggests that hMT+ may not serve as a supramodal motion processing module.
authors.affiliation: Department of Psychology, University of Washington, Seattle, WA 98195, USA; Department of Psychology, University of Nevada Reno, Reno, NV 89557, USA. Electronic address: fangj@unr.edu.
authors.forename: Fang
authors.initials: F
authors.lastname: Jiang
authors.affiliation: Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Beauchamp
authors.affiliation: Department of Psychology, University of Washington, Seattle, WA 98195, USA.
authors.forename: Ione
authors.initials: I
authors.lastname: Fine
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D010812:Physical Stimulation; D013702:Temporal Lobe / Q000502:physiology*; D055698:Touch Perception / Q000502:physiology*; D055815:Young Adult
keywords: Attention; Cross-modal; Multimodal; Multisensory; fMRI