September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
Subcortical and cortical responses to local biological motion as revealed by fMRI and MEG
Author Affiliations
  • Dorita Chang
    Department of Psychology, The University of Hong Kong, Hong Kong
  • Hiroshi Ban
    Center for Information and Neural Networks (CiNet), NICT, Japan
    Graduate School of Frontier Biosciences, Osaka University, Japan
  • Yuji Ikegaya
    Center for Information and Neural Networks (CiNet), NICT, Japan
    Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan
  • Ichiro Fujita
    Graduate School of Frontier Biosciences, Osaka University, Japan
  • Nikolaus Troje
    Department of Psychology, Queen's University, Canada
Journal of Vision August 2017, Vol.17, 64. doi:10.1167/17.10.64
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      Dorita Chang, Hiroshi Ban, Yuji Ikegaya, Ichiro Fujita, Nikolaus Troje; Subcortical and cortical responses to local biological motion as revealed by fMRI and MEG. Journal of Vision 2017;17(10):64. doi: 10.1167/17.10.64.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

We report findings from both human fMRI (n = 35), and MEG (n = 10) experiments that tested neural responses to dynamic ("local", acceleration) cues in biological motion. We measured fMRI responses (3T Siemens Trio, 1.5 mm3) to point-light stimuli that were degraded according to: 1. spatial coherency (intact, horizontally scrambled with vertical order retained, horizontally scrambled with vertical order inverted); 2. local motion (intact, constant velocity); and 3. temporal structure (intact, scrambled). Results from MVPA decoding analyses revealed surprising sensitivity of subcortical (non-visual) thalamic area ventral lateral nucleus (VLN) for discriminating local naturally-accelerating biological motion from constant velocity motion, in addition to a wide cortical network that extends dorsally through the IPS and ventrally, including the STS. Retaining the vertical order of the local trajectories resulted in higher accuracies than inverting it, but phase-randomization did not affect (discrimination) responses. In a separate experiment, different subjects were presented with the same stimuli while magnetic responses were measured using a 360 channel whole head MEG system (Neuromag 360, Elekta; 1000 Hz sampling frequency). Results revealed responses in much of the same cortical network identified using fMRI, peaking at 100-150 ms, and again at 350-500 ms after stimulus onset during which we also observed important functional differences with greater activity in hMT+, LO, and STS for structure-from-motion versus the local natural acceleration stimulus, and greater early (V1-V3) and IPS activity for the local natural acceleration versus constant velocity motion. We also observed activity along the medial surface by 200 ms. The fact that medial activity arrives distinctly following early cortical activity (100-150 ms), but before the 350-500 ms window suggests that the implication of thalamic VLN for biological motion perception observed with fMRI may have arisen from early cortical responses, but not higher order extrastriate cortex.

Meeting abstract presented at VSS 2017

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