EEG, Evoked Potential, and Extracellular Single-Unit Recordings In Vivo

Neurons within the central nervous system transmit information as a pulsed electrical code which is conducted down specialized processes (axons) that connect with other neurons. Each neuron can potentially connect with many other neurons and vice versa. At the sites of connections, information is transmitted across synapses, neurotransmitters are released from presynaptic terminals, and these diffuse to receptor molecules located on the postsynaptic neuron. The latter then converts the chemical code back into electrical signals that are transmitted along the axon of the postsynaptic neuron. Since the brain exerts its complex function through these “simple” electrical signals, the electrical activity of the brain can be measured in spatial scales from the relatively gross potentials using electroencephalography and evoked potentials down to the level of the plasma membrane, where currents produce within a single neuron (single-unit action potential). In this chapter, I briefly describe these recording techniques and experimental approaches.