EEG, Evoked Potential, and Extracellular Single-Unit Recordings In Vivo - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 87

Chapter 6
EEG, Evoked Potential, and Extracellular
Single-Unit Recordings In Vivo
Jie Wu
Abstract
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 mole-
cules 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 briefl y describe these recording techniques and experimental approaches.
Key words: Electroencephalography, Evoked potentials , Single-unit action potential , Electrophysiology,
In vivo recording
1. Introduction
Electroencephalography (EEG) and evoked potential (EP) recordings
were the earliest methods used to monitor brain electrical activity.
Since Hans Berger recorded the fi rst human EEG in 1929, these
techniques have become commonplace tools used in both clinical
diagnosis and basic research aimed at investigating a variety of fun-
damental and clinically relevant questions, such as epilepsy, psy-
chosis, sleep, and anesthesia ( 1-4 ).
EEG is the technique, whereby electrical activity generated
by the brain is amplifi ed and displayed. This method enables one
to assess brain function noninvasively over time. Although many
abnormalities on the EEG are considered to be nonspecifi c, there