June 2004
Volume 4, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2004
A human cortical specialization for the processing of velocity gradients in moving stimuli
Author Affiliations
  • Julio C. Martinez-Trujillo
    Centre for Vision Research, York University, Toronto, Ontario, Canada
  • Jens M. Hopf
    Otto-von-Guericke University, Department of Neurology II, Magdeburg, Germany
  • Stefan Treue
    Cognitive Neuroscience Laboratory, German Primate Center, Goettingen, Germany
  • Richard Wildes
    Centre for Vision Research, York University, Toronto, Ontario, Canada
  • Evgueni Simine
    Centre for Vision Research, York University, Toronto, Ontario, Canada
  • Hans J. Heinze
    Otto-von-Guericke University, Department of Neurology II, Magdeburg, Germany
  • John K. Tsotsos
    Centre for Vision Research, York University, Toronto, Ontario, Canada
Journal of Vision August 2004, Vol.4, 81. doi:10.1167/4.8.81
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to Subscribers Only
      Sign In or Create an Account ×
    • Get Citation

      Julio C. Martinez-Trujillo, Jens M. Hopf, Stefan Treue, Richard Wildes, Evgueni Simine, Hans J. Heinze, John K. Tsotsos; A human cortical specialization for the processing of velocity gradients in moving stimuli. Journal of Vision 2004;4(8):81. doi: 10.1167/4.8.81.

      Download citation file:


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

      ×
  • Supplements
Abstract

It is known that the primate visual system possesses neurons specialized in motion processing. Many of these neurons are selective for the direction of translational motion (i.e. in areas V1, MT) or for the specific arrangement of different motion directions (i.e., in areas MST and 7a) in moving random dot patterns (RDP). Some studies have reported that a subset of neurons in monkey area MT is selective for the orientation of velocity gradients (VG) in such patterns. Currently it is unclear whether humans possess a similar specialization. Here, we use event-related fMRI to investigate this issue. In experimental trials, two RDPs moving in the same direction were presented on a computer screen at both sides of a fixation cross during 500ms. Human observers (n=5) indicated which pattern moved faster. In 1/3th of the trials the RDPs contained a velocity gradient (VG-trials, i.e., dots accelerating), in other 1/3th of the trials dots moved at the same speed (without-VG-trials). In the last 1/3th, the dots were stationary (ST-trials) and subjects indicated which RDP contained more dots. The dots' density and average speed in VG- and without-VG-trials was matched. We measured BOLD responses (neuro-optimized GE Signa LX 1.5 T scanner) while subjects performed the task. In agreement with previous studies, BOLD-related activation was stronger, in VG- and without-SG-trials relative to ST trials, in area V1 and the MT/V5+ complex. We found an increase in activation within the human complex MT/V5+ in VG-trials relative to without-VG-trials. Additionally, we compared the activation evoked by VG-stimuli against the one evoked by expanding patterns containing a similar type of VG but a different arrangement of motion directions. We found that the former patterns evoked a significantly stronger activation within the human MT/V5+ complex relative to the latter. Our results suggest that the human motion processing system possess specialized regions for the processing of VG information in moving stimuli.

Martinez-Trujillo, J. C., Hopf, J. M., Treue, S., Wildes, R., Simine, E., Heinze, H. J., Tsotsos, J. K.(2004). A human cortical specialization for the processing of velocity gradients in moving stimuli [Abstract]. Journal of Vision, 4( 8): 81, 81a, http://journalofvision.org/4/8/81/, doi:10.1167/4.8.81. [CrossRef]
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×