Synaptic Gating - Gated Synapse Model

Gated Synapse Model

The model for gated synapses was originally derived from the model electronic circuit, in which the gatekeeper serves as a transistor in a circuit. In a circuit, a transistor can act as a switch that turns an electrical signal on or off. In addition, a transistor can serve to amplify an existing current in a circuit. In effect, the gatekeeper neuron acts as the transistor of a gated synapse by modulating the transmission of the signal between the pre-synaptic and post-synaptic neurons.

In a model gated synapse, the gate is either open or closed by default. The gatekeeper neuron, therefore, serves as an external switch to the gate at the synapse of two other neurons. One of these neurons provides the input signal and the other provides the output signal. It is the role of the gatekeeper neuron to regulate the transmission of the input to the output. When activated, the gatekeeper neuron alters the polarity of the presynaptic axon to either open or close the gate. If this neuron depolarizes the presynaptic axon, it allows the signal to be transmitted. Thus, the gate is open. Hyperpolarization of the presynaptic axon closes the gate. Just like in a transistor, the gatekeeper neuron turns the system on or off; it affects the output signal of the postsynaptic neuron. Whether it is turned on or off is dependent on the nature of the input signal (either excitatory or inhibitory) from the presynaptic neuron.