2007 Sensory Physiology

Topographic maps

Spatial representation

  • the location of rods and cones within the retina determines the topographic representation of space within the visual pathway - this receptive field map is maintained centrally, forming a topographic map in the primary visual cortex (V1)
    • inputs from the fovea (green) are overrepresented compared to the periphery (blue)
Topographic map of visual cortices

 

  • there is only one map of visual space
  • i.e, there's a separate map for each visual field, not a map for each eye
  • this is established by the crossing of the fibres at the optic chiasm, where axons from the nasal retinas cross, but axons from the temporal retinas don't
    • this means that ganglion cells (in both eyes) that have receptive fields in the left visual field project to the right thalamus and vice versa
    • depth perception (the ability of the brain to create three-deimensional representations of objects) is dependent on binocular vision

.

 

Visual system pathways

S&G Figure 10.36

Site Map | Email: Dr. Janet Fitzakerley | ©2007 University of Minnesota Medical School Duluth | Last modified: 11-oct-07 9:55 AM