Potential Role of Synaptic Activity to Inhibit LTD Induction in Rat Visual Cortex

Figure 5

Averaged power spectra for ECoG activity (band-pass filtered between 0.1 and 5 Hz) recorded in V1 of urethane-anesthetized rats. (a) Baseline (prestimulation) ECoG activity showed prominent slow wave activity with peak power between 0.6 and 0.8 Hz. Application of LFS to the LGN enhanced power between 0.6 and 2 Hz. (b) RF stimulation alone or (c) paired LFS + RF stimulation suppressed very low-frequency (~0.6 Hz) power, strongly enhanced power around 1 Hz, and resulted in the appearance of power peaks at ~1.8, 2.7, and 3.5 Hz. (d) Rats treated with a combination of scopolamine and mecamylamine (scopol., 10 mg/kg + mecamyl., 5 mg/kg) continued to exhibit the novel power peaks elicited by LFS + RF stimulation. Power spectra are group averages (n’s for all groups, the same as above) and were calculated for 30-second epochs recorded prior to and during delivery of the stimulation protocol. For each rat, power was normalized to the peak power present in the baseline ECoG epoch.

(a) LFS

(b) RF stim.

(c) LFS + RF stim.

(d) LFS + RF stim.: scopol. + mecamyl