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. 2012 Jul 25;7(7):e40601. doi: 10.1371/journal.pone.0040601

Figure 3. Inhibitory synapses.

Figure 3

A. An AP evoked in the presynaptic inhibitory neuron and the simultaneously recorded IPSP (average of 15 traces, each) from the postsynaptic excitatory neuron at two membrane potentials. The IPSP was hyperpolarizing at a Vm of −50 mV but depolarizing at −75 mV. B. The IPSP amplitude plotted as function of the membrane potential (Vm). The data were fitted with a straight line (dashed) intercepting the x-axis (indicated by an arrow) at −65 mV. C. In 7 subsequent traces, IPSP amplitudes varied in response to single presynaptic APs, but no failures were observed. The postsynaptic Vm was held at −50 mV D. A histogram of the IPSP amplitudes (filled bars) was constructed from 60 traces and the background noise (empty bars). The IPSP histogram was fitted with a Gaussian distribution with a median at −0.53 mV (arrow) and a σ of 0.36 mV.