Axon terminal

When an action potential arrives at an axon terminal (A), the neurotransmitter is released and diffuses across the synaptic cleft.

[1] Neurotransmitter molecules are packaged into synaptic vesicles that cluster beneath the axon terminal membrane on the presynaptic side (A) of a synapse.

[1] Historically, calcium-sensitive dyes were the first tool to quantify the calcium influx into synaptic terminals and to investigate the mechanisms of short-term plasticity.

[7] Another possibility is constructing a genetically encoded sensor that becomes fluorescent when bound to a specific neurotransmitter, e.g., glutamate.

[8] This method is sensitive enough to detect the fusion of a single transmitter vesicle in brain tissue and to measure the release probability at individual synapses.