Thursday, May 28, 2009

Apical Dendrite

An apical dendrite is a dendrite which projects from the apex of a pyramidal neuron. The apical dendrite belongs to one of two primary categories of dendrites, and it distinguishes the pyramidal neuron from the spiny stellate cell in the cortices. Pyramidal cells are found in the prefrontal cortex, the hippocampus, the entorhinal cortex, and the olfactory cortex. Dendrite arbors formed by apical dendrites are the means by which synaptic inputs into a cell are integrated.

The apical dendrites in these regions contribute significantly to memory, learning, and sensory associations by modulating the excitatory and inhibitory signals received by the pyramidal neurons. Apical dendrites can be divided into two categories: distal and proximal. The longer distal apical dendrites project from the pyramidal neuron body opposite from the axon. Distal apical dendrites form non-local synapses. Shorter proximal apical dendrites project radially to local pyramidal cells and interneurons. Pyramidal neurons segregate their inputs using proximal and apical dendrites.