Table 1.

Amplitude modulation

			VPL			S1
Monkey	Set	Condition	r	P	n	r	P	n
m26	1	Active task	0.786	<0.05	23	1	<0.001	31
m26	2	Active task	0.881	<0.01	15	0.976	<0.001	28
m27	1	Active task	0.607	0.167	20	0.750	0.066	3
m26	1	Passive control	0.857	<0.05	13	0.964	<0.01	19
m26	2	Passive control	0.810	<0.05	8	0.929	<0.01	16
m27	1	Passive control	0.857	<0.05	11	—	—	—

Power spectra at 20 Hz during the stimulus window (t = 0–0.5 s) were averaged over trials per stimulus-amplitude class. A positive modulation of 20-Hz power by the stimulus amplitude was observed (Spearman correlation).