Active properties of dendrites

Dendrites (from the Latin word Dendron, meaning “tree”) are extensions from the cell body of neurons and are the recipient site for the majority of synaptic inputs. These inputs are processed and integrated within the dendrites, leading in some cases to the generation of dendritic supra-threshold responses, or dendritic spikes, and ultimately initiate a somatic action potential – the final output of the neuron –in the axon initial segment.

Dendrites are not passive structures, but express a myriad of different types of voltage-gated ion channels that both regulate the integration of synaptic inputs as well as the generation and propagation of dendritic spikes. Many of these channels undergo various forms of activity-dependent plasticity (called “intrinsic plasticity”), which operate in parallel with well-known forms of synaptic plasticity. The expression and function of ion channels in dendrites have also been shown to be abnormal in several disease models suggesting that both genetic and acquired “channelopathies” may be an underlying mechanism of the disease state.

The dendrites of many neurons are also covered by thousands of small membrane protrusions called dendritic spines. Their peculiar morphology, with a small head connected to the dendritic shaft by a slender neck, has inspired decades of theoretical – and more recently experimental – work, in an attempt to understand how the voltage signal generated by synaptic input at the spine head is delivered to the parent dendrite, and the effect this has on the processing of synaptic inputs.

With the advent of advanced optical techniques, in particular two-photon laser microscopy, it has become possible to image and photo-activate dendritic spines deep in tissue with high spatial resolution. In combination with electrophysiological and molecular tools, there is now a wealth of information on the molecular identity, distribution, and function of a range of different voltage-gated channels in both dendrites and spines.

The aim of this Research Topic in Frontiers of Neuroscience is to describe the molecular characteristics, subcellular distribution, and function of the voltage-gated channels presently known to exist in the spines and dendrites. Furthermore, this Research Topic will include an overview of some of the technical advances made and the challenges facing investigators using optical, molecular, and electrophysiological methods to uncover the role of dendrites and spines in brain function in both health and disease.