Receptive field properties.

<p>a) Maximum number of spikes in response to a black or white stimulus for the superficial layers, intermediate layers and deep layers. Responses to white stimuli are shown in white and responses to black stimuli in black. b) Average size of the black subfield and the white subfield for the superficial layers, intermediate layers and deep layers. Responses to white stimuli are shown in white and responses to black stimuli in black. c) Sizes of the black subfield and the white subfield in relation to the recording depth in the optic tectum. Open circles represent the white subfields while closed circles represent the black subfields. d) Average contrast index for the superficial (shown in light grey), intermediate (shown in dark grey) and deep layers (shown in black). Negative values represent neurons whose black subfield was larger, while positive values represent neurons whose white subfield was larger. e) Distribution of the contrast index values for the superficial layers (shown in light grey), intermediate layers (shown in dark grey) and deep layers (shown in black). Please notice that the majority of the neurons has a contrast index >0 indicating a larger subfield for black than for white. Error bars represent standard errors. *p<0.05.