Neuromagnetic correlates of visual motion coherence

Eur J Neurosci. 2005 Dec;22(11):2937-45. doi: 10.1111/j.1460-9568.2005.04473.x.


In order to characterize cortical responses to coherent motion we use magnetoencephalography (MEG) to measure human brain activity that is modulated by the degree of global coherence in a visual motion stimulus. Five subjects passively viewed two-phase motion sequences of sparse random dot fields. In the first (incoherent) phase the dots moved in random directions; in the second (coherent) phase a variable percentage of dots moved uniformly in one direction while the others moved randomly. We show that: (i) visual-motion-evoked magnetic fields, measured with a whole-scalp neuromagnetometer, reveal two transient events, within which we identify two significant peaks--the 'ON-M220' peak approximately 220 ms after the onset of incoherent motion and the 'TR-M230' peak, approximately 230 ms after the transition from incoherent to coherent motion; (ii) in lateral occipital channels, the TR-M230 peak amplitude varies with the percentage of motion coherence; (iii) two main sources are active in response to the transition from incoherent to coherent motion, the human medial temporal area complex/V3 accessory area (hMT+/V3A) and the superior temporal sulcus (STS), and (iv) these distinct areas show a similar, significant dependence of response strength and latency on motion coherence.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cerebral Cortex / diagnostic imaging
  • Cerebral Cortex / physiology*
  • Data Interpretation, Statistical
  • Female
  • Functional Laterality / physiology
  • Humans
  • Magnetic Resonance Imaging
  • Magnetoencephalography*
  • Male
  • Motion Perception / physiology*
  • Photic Stimulation
  • Positron-Emission Tomography
  • Visual Perception / physiology*