Synapse

Synapses are specialized junctions through which cells of the nervous system signal to one another and to non-neuronal cells such as muscles or glands. Synapses define the circuits in which the neurons of the central nervous system interconnect. They are thus crucial to the biological computations that underlie perception and thought. They also provide the means through which the nervous system connects to and controls the other systems of the body.

Table of contents

1 Anatomy and Structure 2 Signalling across the Synapse 3 Synaptic strength 4 Integration of synaptic inputs 5 Detailed properties and regulation

Anatomy and Structure

At a prototypical synapse, such as a dendritic spine, a mushroom-shaped bud projects from each of two cells and the caps of these buds press flat against one another. At this interface, the membraness of the two cells flank each other across a slender gap, the narrowness of which enables signaling molecules known as neurotransmitters to pass rapidly from one cell to the other by diffusion. This gap is sometimes called the synaptic cleft.

Synapses are asymmetric both in structure and in how they operate. Only the so-called pre-synaptic neuron secretes the neurotransmitter, which binds to receptorss facing into the synapse from the post-synaptic cell. The pre-synaptic nerve terminal generally buds from the tip of an axon, while the post-synaptic target surface typically appears on a dendrite, a cell body or another part of a cell.