Weak light stimulation of pyramidal cells reduces gamma power.

<p>A. Raw trace of the LFP measured in the CA3 stratum radiatum of a hippocampal slice. Background drive given by 400 nM kainic acid induced gamma oscillations (peak frequency Hz. A 100 ms, weak (1–3 ) pulse of blue light, indicated in blue, reduced the amplitude of the ongoing oscillations. B. Population data from 94 trials, 8 slices plotting energy in the gamma band (25–50 Hz) as a function of time. The average energy during the stimulation period was of the pre-stimulation baseline. The dashed lines indicate one estimated standard deviation.