Figure 5

CCh-induced depression of synaptic transmission is due to activation of muscarinic receptors. A, B. Voltage traces of a rat neocortical neurone (top traces) and simultaneously recorded field potentials (bottom trace) in control condition (A) and in the presence of 10 μM carbachol (CCh) (B). The traces show synaptic responses elicited by orthodromic stimulation (100 μs, 20 V). Note the depressant effect of CCh on the amplitude of EPSP and field potential. C. Plot of the average EPSP amplitudes vs. stimulus intensity (input–output curve) in control conditions and in the presence of CCh as indicated (n = 45). D. Plot of the average field potential amplitudes vs. stimulus intensity in control and in the presence of CCh (n = 42). These experiments were performed in STRC. **: p < 0.01, ***: p < 0.001