Line Orientation Demo

Sweeping lines and  cortical response Orientation key Orientation map
a b c d e
f
g h
Key:
  1. retinal image presented to map g.
  2. initial response of the cortex to that image
  3. orientation histogram of the initial response
  4. settled response of the cortex to that image
  5. orientation histogram of the settled response
  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 is presented. A version of this page with smaller pictures is also available.

First check out the spinning RF-LISSOM orientation demo, because that version has more detailed documentation. These images happen to be from a smaller network (96x96) but use otherwise similar parameter settings. The entire retina is shown here; usually the retinal area outside the white outline is ignored. The retinal input has been colored according to its orientation here for convenience, but the actual input was monochrome.

Notice that as each oriented line sweeps across the orientation map, it activates only those neurons with orientation preferences similar to the input orientation. At the same time, the position and shape of the input is encoded in the position and shape of the cortical activity. Near the borders of the cortex, there are distortions that are an artifact of the limited lateral connectivity of those neurons, but a straight line should still be perceived because all of the activated neurons code for similar orientations.

To see more clearly how the various orientations are overlaid to make the full orientation map, see the Full Map Demo, which is a slightly different view of the same data.