Dendritenspines

Dendritenspines, or dendritic spines, are small membranous protrusions on the dendrites of neurons. Most are the postsynaptic sites of excitatory synapses and contain a postsynaptic density rich in glutamate receptors, scaffolding proteins, and signaling molecules. The spine usually has a bulbous head connected to the dendrite by a narrow neck, a morphology that helps compartmentalize calcium signals and biochemical cascades within the synapse.

Spine morphology varies and includes mushroom, thin, stubby, and filopodia-like forms. Spines are highly dynamic and continually remodel in response to neuronal activity. The density and shape of spines correlate with synaptic strength and plasticity, influencing how neurons store and process information.

Formation and maintenance of dendritic spines depend on the actin cytoskeleton and signaling networks, including Rho family GTPases, CaMKII, and PSD-95. Activity-dependent remodeling underlies synaptic plasticity phenomena such as long-term potentiation and long-term depression, which contribute to learning and memory.

Clinical and research significance: changes in spine density or morphology are associated with cognitive function and various neurological conditions. Spine loss or abnormal spine shape is observed in neurodegenerative diseases such as Alzheimer's disease and in neurodevelopmental disorders including fragile X syndrome and autism. Studying dendritic spines provides insight into synaptic connectivity, plasticity, and the cellular basis of learning. Imaging techniques such as confocal and two-photon microscopy enable visualization of spine structure and dynamics in living tissue.