Figure 4
Effects of cholinergic compounds on synaptic inhibition. A, B. Voltage traces of a neurone in control conditions and in the presence of CCh. Orthodromic stimulation elicited compound synaptic responses consisting of an EPSP, IPSPA and IPSPB. The two IPSPs are particularly obvious at less negative membrane potentials. The membrane potential was altered by current injections (+0.4, 0, -0.4 nA, from top to bottom). B: Traces from the same neurone in the presence of CCh. Note the marked decrease in the amplitudes of IPSPA and IPSPB in the top trace. C,D: Plot of the membrane potentials obtained by different current injections (−0.4 to + 0.4, 0.05 nA increment) at different times of the traces shown in A and B. The different symbols denote the different times indicated in A and B. Note the decrease in IPSPA and IPSPB conductances obvious from the steeper current voltage relationship. E. Plot of the mean gIPSP-A and gIPSP-B in control and in the presence of CCh as indicated. F. Plot of the mean gIPSP-B values in control, in the presence of xanomeline (xano) and xanomeline + CCh. The vertical bars represent the s.e.m