Glossary
Synapse
What is a synapse?
A synapse is a junction through which a neuron signals another cell. The receiving cell is often another neuron, but it can also be a muscle or gland cell.
Chemical and electrical synapses
At a chemical synapse, neurotransmitters cross a small gap and act on receptors in the receiving cell. At an electrical synapse, gap-junction channels allow direct passage of current between cells. Electrical transmission is often bidirectional, although some junctions favor one direction.
Parts of a chemical synapse
- Presynaptic terminal: The sending end, where vesicles store neurotransmitter.
- Synaptic cleft: The gap the released transmitter crosses.
- Postsynaptic membrane: The receiving surface, with receptors that respond to transmitter.
In a typical chemical synapse, an arriving action potential triggers transmitter release. The effect depends on the transmitter and receptors involved; it may make the receiving neuron more or less likely to fire.
Learning and memory
Synaptic transmission can change with activity and experience. This synaptic plasticity is an important subject in research on learning and memory.
Why it matters
Synapses are where cells communicate, and changes in that communication can affect a circuit. Studying synaptic dysfunction can help explain neurological problems, but a finding at one junction does not explain a whole disorder on its own.