dendrites

Dendrites are the branched extensions of neurons that receive synaptic input and transmit electrical signals toward the cell body. The dendritic tree increases a neuron's receptive surface area and forms complex, tree-like arbors that vary across neuron types. Dendritic spines are small membranous protrusions along dendrites; most excitatory synapses in the cortex and hippocampus form on these spines, whose number and shape can change with activity.

Electrical signaling in dendrites is governed by passive cable properties and by active ion channels. Synaptic inputs generate postsynaptic potentials that decay with distance from the synapse, leading to spatial and temporal summation at the soma. Dendrites can also support local regenerative events, or dendritic spikes, mediated by NMDA receptors and voltage-gated calcium channels, which can influence spike initiation at the axon hillock.

Different neurons exhibit diverse dendritic morphologies. Pyramidal neurons have apical and basal dendrites, while interneurons may have compact or highly branched arbors. Dendritic development continues after birth, with growth, pruning, and spine turnover driven by experience and learning.

Dendrites are essential for the computational capabilities of neurons, supporting spatial and temporal integration and coincidence detection. Abnormal dendritic structure or spine dynamics are linked to several neurological and psychiatric disorders, highlighting their role in health and disease.