User:Dbaush/Synaptic Gating Draft

Synaptic gating is the ability of neural circuits to "gate" inputs by either suppressing or facilitating specific synaptic activity. Selective inhibition of certain synapses has been studied thoroughly (see Gate theory of pain); however, recent studies have supported the existence of permissively gated synaptic transmission.

Suppressive synaptic gating
During the locomotor cycle, central locomotor circuits have the ability to inhibit neurotansmitter release from sensory afferent neurons. This prevents the relay of sensory input at inappropriate times.

Permissive synaptic gating
Synaptic gating encompasses a variety of mechanisms by which the efficacy of neuronal activity is modulated. Recent studeis have been done which demonstrate the permissive properties of synaptic gating. In certain instances, membrane depolarization can cause an opening of these 'gates' which previously had an inhibitory effect on the neuron they were gating. It is more than a matter of simple summation, however, in that, summation is the convergence of many EPSPs - either from a single neuron firing at a high frequency or from many neurons firing at once - at the axon hillock that depolarizes the membrane potential to the point of threshold. With synaptic gating, the membrane depolarization causes an increase in intracellular levels of calcium that will permit the presence of an action potential to release neurotransmitters.