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

Figure 2

Plot of fPSP amplitude (normalized to baseline) in V1 of individual rats at six time points throughout the experiment. Application of LFS () to the LGN resulted in significant depression of fPSP amplitude in the large majority of animals (7/8 or 8/8, depending on the time following stimulation). Combined LFS + RF stimulation (), RF stimulation alone (), or LFS + RF stimulation in rats pretreated (i.p.) with acetylcholine receptor (AChR) antagonists () resulted in heterogeneous responses, with about half of the rats in each group exhibiting potentiation, while the remaining ones showed depression of fPSP amplitude at most time points following delivery of the stimulation protocol (the AChR antagonist condition is comprised of 1 mg/kg scopolamine, ; 0.5 mg/kg mecamylamine, ; 10 mg/kg scopolamine + 5 mg/kg mecamylamine, ; total ; see text and Figure 3 for details).