STRFs for LFP (left) and for MSU activity (right) averaged over the 16-electrode array.

The two panels represent an average of the data shown in Figure 5. For the left panel blue indicates negative LFP amplitudes, red colors indicate positive amplitude values and yellow corresponds to zero crossings. Contour lines indicate 25, 50 and 75% of LFP negative maximum (white) and positive maximum (red). Note peak spike activity in the 50–75% negative LFP-amplitude contour lines.