Orientation Map Demo

Sweeping lines and accumulate cortical response Orientation key Orientation map
a b c d e
f
g h
Key:
  1. retinal image presented most recently to map g.
  2. peak initial responses of cortex so far
  3. peak initial orientation histogram values so far
  4. peak settled response of cortex so far
  5. peak settled orientation histogram values so far
  6. key showing color assigned to each angle
  7. self-organized RF-LISSOM orientation map
  8. orientation histogram of the orientation map
The sequence repeats after each of the four orientations are presented. A version of this page with smaller pictures is also available.

First check out the Line Orientation Demo, which shows how the cortex responds to each individual stimulus. The images on this page show the same data except that once a cortical unit or histogram bar has reached a certain level, it remains on. Thus, over time, the cortical images show the history of the peak responses to the inputs.

Each time an oriented line is presented, the areas whose colors match that line are filled in; by the time the last is presented, the entire orientation map has been revealed. Since the lines activate broad, overlapping ranges of orientations, each successive line activates a smaller number of new units than the previous; by the end of the third orientation shown, only a few units remain to be filled in.

Note that the accumulated histograms show the peak level of the indicated orientation bin, i.e. the peak percentage activated at any one time. This is an inherently noisy measurement because it is determined by a very small number of border units as each line reaches the edge of the retina. However, if you disregard the noisy peaks, even the histograms demonstrate the gradual filling-in of the full range of orientations.