Fig. 4.

Cholinergic synaptic currents are excitatory. A, Averaged mEPSCs (>20 traces at each potential) recorded in the presence of 1 μm TTX from a single neuron at 6 DIV at indicated holding potentials. The peak current–voltage relationship indicates a reversal potential near 0 mV. B, In current-clamp mode, nAChR-mediated sEPSPs were recorded from a single neuron (6 DIV) at two different holding potentials. At rest, −35 mV in this neuron, an sEPSP triggers a spontaneous AP with a threshold at −28 mV. When the cell is held at −55 mV by injection of hyperpolarizing current, the sEPSPs are depolarizing, but they do not give rise to regenerative events.