| ISLE | Chapter 3
| Compound Eyes
In the compound eye, there is not a single entrance to the eye, but many small structures called ommatidia. The surface of the eye is then a complex faceted structure with each facet being the entrance to a different ommatidia. Each ommatidia has its own small lens and a small collection of pigment cells that capture the light and do transduction. These different ommatidia have their own neural connections but they also interact similar to light falling on one cone inhibiting light responses to adjacent cones through horizontal cells. As such, these eyes have lateral inhibition. In fact, one of the very early studies of lateral inhibition is in the compound eye of the limulus or horseshoe crab (Hartline & Ratliff, 1958). Compound eyes are particularly good at detecting motion. Given the size of the ommatidium relative to our receptors, motion of objects creates a flicker effect as adjacent ommatidia turn on and off.
In the video below you can see further discussion and some simulations of how some different compound eyes see. Remember this is a simulation. There are many types of compound eyes and all of them work differently than human eyes. More importantly, we have different brains behind our eyes. So this simulation only superficially captures some aspects of compound eye vision. On the illustration you can interact with compound eyes and try different stimuli and photographs to see how different compound eyes work.
To see the illustration in full screen, which is recommended, press the Full Screen button, which appears at the top of the page.
On the Illustration tab, you can stimulate a region of the retina and see the effect on the single cell you are recording from.
Below is a list of the ways that you can alter the model. The settings include the following:
Choose a Stimulus: Select from a predtermined set of stimluli to present
to the compound eye. The stimulus will be shown on the far left and the responses for the row
of ommatidia outlined in red will be plotted in the middle. You can move your stimuli around by touching
or dragging the stimulus with mouse of finger.
Image as Compound Eye Sees: Process the image so that it, in similation,
appears as the compound eye might experience it.
Ommatidia Size: Make the ommatidia smaller, more resolution, or larger,
less resolution, to see how different types of compound eyes might experience the same scene.
Plot Level: Choose the row of ommatidia to show in the graph in the
middle of the screne.
Show Cells: Show or hide outlines of the ommatidia on the region where the
stimulus is displayed.
Pressing this button restores the settings to their default values. It also gets you a new cell which might have a different receptive field.