Effect of NB stimulation on multiunit activity throughout the depth of cortex. (a) Multiunit spike rate (color coded, scale bar on the right) recorded by the polytrode plotted against cortical depth and time during one repeat of a natural movie (only 18 of the 27 polytrode channels are shown). (b) Multiunit responses to the first 10 repeats (trials) of the movie, before (control) and 0 to 5 s after NB stimulation, both plotted on the color scale shown in (a).