(1) A synapse in which the nerve impulse in a presynaptic cell tend to increase the probability of the postsynaptic cell to fire an action potential.
(2) A synapse wherein a nerve impulse in the presynaptic cell results in the release of excitatory neurotransmitters that open ion channels in the postsynaptic cell membrane where positive ions can move into, causing a transient depolarization that increases the likelihood of postsynaptic cell to fire an action potential.
The amino acid glutamate is the major excitatory neurotransmitter in an excitatory synapse in the central nervous system of vertebrates.
Compare: inhibitory synapse
See also: synapse