Neurons and Synapses

Neurons are highly specialized for signal processing and conduction via electrochemical processes. The morphological structure of a neuron includes a cell body, called the soma, and elaborate branching structures that enable communication with sensory receptors, distant neurons, etc. In the simplest view, input and output are handled separately. Inputs are collected in a continuous fashion by the dendrites, and represented as a variation of the transmembrane voltage. Multiple inputs are summed in the dendritic tree, and the net input is represented as transmembrane voltage at the soma. When the soma voltage reaches some threshold, a discrete voltage pulse is generated, called an action potential, which propagates down the axon as output. The end of the axon also has elaborate branching to enable communication with target neurons. The input-output properties of neurons have been studied extensively and modeled in detail (Koch and Segev 1989).

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