Explain the physiological mechanism that creates center-surround receptive fields by explaining what happens when you look at a book that is sitting on top of a desk.

Question

What will be an ideal response?

Answer 1

When you look at a book sitting on a desk, the image of the book is projected onto the fovea. Cones in the fovea initiate an excitatory signal in response to light reflecting off the book. This signal then moves to the bipolar and horizontal cells. In response to the signal from the cones, horizontal cells send inhibitory signals back to adjacent cones and send excitatory signals across to other horizontal cells, thus increasing the inhibitory feedback on the cones. This inhibition decreases across space, so that cones farther from the source of the image are less inhibited. The combination of the positive signals coming from bipolar cells and the inhibition coming from the horizontal cells determines the strength of a signal to a retinal ganglion cell, which then has its own center-surround characteristics. The result of these complex processes is lateral inhibition, which facilitates edge detection.