Dendritic Spines

Abstract

Dendritic spines are small protrusions from dendrites that host the majority of excitatory synapses in the central nervous system. Structurally, excitatory synapses located on dendritic spines are asymmetric, with a presynaptic bouton that contains round clear vesicles apposed to a postsynaptic density where glutamate receptors are anchored. Spines form biochemical compartments that can isolate activated signalling pathways that occur at one synapse from those at other synapses, thereby providing a way to enhance the specificity of connections between neurons in the brain. Structural changes of dendritic spines in response to stimulation facilitate changes in synaptic strength, and these changes are likely to underlie important higher brain functions such as learning and memory. Dysregulation of spine morphology is seen in several neurological disorders such as Alzheimer's disease and fragile X syndrome. Key Concepts Spines are the primary site of excitatory synapses. Smooth endoplasmic reticulum can form complex structures localized to large spines. The cytoskeleton of spines is mostly composed of actin. Trans‐synaptic adhesion molecules as well as proteins secreted from astroglia help stabilise synapses. Spines can act as small biochemical compartments. Spine structure is responsive to activity.