title: Separate Perceptual and Neural Processing of Velocity- and Disparity-Based 3D Motion Signals.
abstract: Although the visual system uses both velocity- and disparity-based binocular information for computing 3D motion, it is unknown whether (and how) these two signals interact. We found that these two binocular signals are processed distinctly at the levels of both cortical activity in human MT and perception. In human MT, adaptation to both velocity-based and disparity-based 3D motions demonstrated direction-selective neuroimaging responses. However, when adaptation to one cue was probed using the other cue, there was no evidence of interaction between them (i.e., there was no "cross-cue" adaptation). Analogous psychophysical measurements yielded correspondingly weak cross-cue motion aftereffects (MAEs) in the face of very strong within-cue adaptation. In a direct test of perceptual independence, adapting to opposite 3D directions generated by different binocular cues resulted in simultaneous, superimposed, opposite-direction MAEs. These findings suggest that velocity- and disparity-based 3D motion signals may both flow through area MT but constitute distinct signals and pathways.
  
  
  
  Recent human neuroimaging and monkey electrophysiology have revealed 3D motion selectivity in area MT, which is driven by both velocity-based and disparity-based 3D motion signals. However, to elucidate the neural mechanisms by which the brain extracts 3D motion given these binocular signals, it is essential to understand how-or indeed if-these two binocular cues interact. We show that velocity-based and disparity-based signals are mostly separate at the levels of both fMRI responses in area MT and perception. Our findings suggest that the two binocular cues for 3D motion might be processed by separate specialized mechanisms.
authors: Center for Perceptual Systems, sjjoo@uw.edu.|Department of Psychology, and.|Department of Neuroscience, The University of Texas at Austin, Austin, Texas 78712, and.
authors: Sung Jun
authors: 0000-0001-6915-6992
authors: SJ
authors: Joo
authors: Center for Perceptual Systems.|Department of Psychology, and.|Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461.
authors: Thaddeus B
authors: 0000-0002-5009-7889
authors: TB
authors: Czuba
authors: Center for Perceptual Systems.|Department of Psychology, and.
authors: Lawrence K
authors: 0000-0002-3958-781X
authors: LK
authors: Cormack
authors: Center for Perceptual Systems.|Department of Psychology, and.|Department of Neuroscience, The University of Texas at Austin, Austin, Texas 78712, and.
authors: Alexander C
authors: 0000-0003-1430-6935
authors: AC
authors: Huk
mesh_terms: D000328:Adult; D003463:Cues; D005260:Female; D005366:Figural Aftereffect; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*; D059906:Neuroimaging; D010775:Photic Stimulation; D015357:Vision Disparity / Q000502:physiology; D015348:Vision, Binocular / Q000502:physiology; D014793:Visual Cortex / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*
keywords: 3D motion; binocular vision; changing disparity; fMRI; interocular velocity difference; motion aftereffect