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→Postsynaptic Mechanisms of Chemical Transmission
* Once transmitter binds to the postsynaptic membrane, the ion channels for this synapse open, and allow the ions that they permeate to flow through them. The membrane, which was sitting at -90mV, begins to rapidly depolarize towards the reversal potential of the synapse (+20 mV). The activation of the synaptic ion channels is represented in the electrical equivalent circuit by showing that the switch has closed (Figure 6, panel 2). Current flows into the cell through the synaptic ion channels, those gated by binding the transmitter; current flows out of the adjacent non-synaptic membrane through the ungated leak channels and through the capacitor, so that <math>I_{EPSP} = I_{L} + I_{C}</math>.
* At the peak of the synaptic potential, the capacitance of the membrane is neither charging nor discharging, so that the membrane is in a steady state (Figure 6, panel 3). At this point, <math>I_{EPSP} = -I_{L}</math>.
* After transmitter binds receptors, the receptors and transmitter may unbind, and the transmitter may be rapidly removed from the synaptic cleft by enzymes that inactivate the transmitter, by being re-uptaken into the presynaptic terminal, or by diffusing away from the synaptic cleft. In addition, the receptor may inactivate, becoming unresponsive to the transmitter; or the channel may inactivate.
