synapse

n. the specialized junction through which neural signals are transmitted from one neuron (the presynaptic neuron) to another (the postsynaptic neuron). In most synapses, the knoblike ending (terminal button) of the axon of a presynaptic neuron faces the dendrite or cell body of the postsynaptic neuron across a narrow gap, the synaptic cleft. The arrival of a neural signal triggers the release of neurotransmitter from synaptic vesicles in the terminal button into the synaptic cleft. Here the molecules of neurotransmitter activate receptors in the postsynaptic membrane and cause the opening of ion channels in the postsynaptic cell. This may lead to excitation or inhibition of the postsynaptic cell, depending on which ion channels are affected. Also called synaptic junction. See also axo-axonal synapse; electrical synapse. —synaptic adj.

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Psychology term of the day

November 15th 2024

operant behavior

behavior that produces an effect on the environment and whose likelihood of recurrence is influenced by consequences (see operant). Operant behavior is nearly synonymous with voluntary behavior.