Activation of human extrageniculostriate pathways after damage to area V1

Neuroimage. 1999 Jan;9(1):97-107. doi: 10.1006/nimg.1998.0390.


We have used positron emission tomography (PET) to specify the cortical and subcortical structures activated following visual stimulation of the scotomatous field in a patient with an asymmetric bilateral developmental anomaly of the visual cortex. Computerized perimetry indicated a left visual field defect only although MRI and 18FDG-PET scans showed abnormalities in both occipital lobes. The visual stimuli were semicircular gratings moving in opposite directions on a dynamic random-dot background. They were specifically constructed to eliminate intra- and extraocular light scatter and to optimize the activation of extra-striate cortical areas and their projecting subcortical relays. For anatomical localization PET images were coregistered to the subject's MRI in Talairach coordinates. After subtraction of the baseline conditions from the stimulation conditions, a t-statistic map was created on a voxel-by-voxel basis. Stimulation of the scotomatous hemifield yielded significant activations of Brodmann cortical areas 18-19 and 47 as well as the pulvinar thalami of the left hemisphere, in addition to a less prominent activation in the right hemisphere. Stimulation of the intact hemifield produced significant activation of Brodmann cortical areas 30 and 47 of the left hemisphere. These results suggest that in the absence of area V1, residual vision observed in the blind hemifield could be mediated by a retinofugal pathway to extrastriate cortex via the pulvinar.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain Damage, Chronic / diagnostic imaging*
  • Brain Mapping
  • Dominance, Cerebral / physiology
  • Female
  • Geniculate Bodies / abnormalities*
  • Geniculate Bodies / diagnostic imaging
  • Hemianopsia / diagnostic imaging
  • Humans
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Imaging
  • Motion Perception / physiology
  • Pattern Recognition, Visual / physiology
  • Scotoma / diagnostic imaging*
  • Synaptic Transmission / physiology
  • Tomography, Emission-Computed*
  • Visual Cortex / abnormalities*
  • Visual Cortex / diagnostic imaging
  • Visual Fields / physiology
  • Visual Pathways / diagnostic imaging*