Spatiotemporal Effects of Synaptic Current

A neuron receives excitatory and inhibitory electrical signals from other neurons via synaptic connections on dendritic spines, branches, or somatic membranes. These signals travel from different locations to the soma depolarizing or hyperpolarizing the membrane, thus regulating cell excitability. Although this is a straightforward concept, there are a multitude of intricate details that occur at the neuronal level, which regulate this process. This chapter looks to describe these spatiotemporal details of synaptic input so that the beginning electrophysiologist can become aware of the full potential of neuronal communication. To begin, we discuss Wilfrid Rall’s cable theory followed by empirical evidence supporting or refuting Rall’s predictions. This is followed by an introduction into Hebbian plasticity or spike-timing-dependent plasticity (STDP), which is a process critically dependent upon the temporal firing activity of both presynaptic and postsynaptic neurons.