EEG, Evoked Potential, and Extracellular Single-Unit Recordings In Vivo - Animal Models of Acute Neurological Injuries: Injury and Mechanistic Assessments - page 88

are a number of specifi c EEG fi ndings that are diagnostic of a
particular condition, state, or lesion within the central nervous
system (CNS). EEG recordings refl ect the cumulative synaptic
activity from extracellular ionic currents induced by dendritic elec-
trical activity.
EP on the other hand is an electrical potential recorded from
the CNS of a human or animals following presentation of a stimu-
lus, as distinct from spontaneous potentials as detected by EEG.
EPs are small electrical events arising from neural tissue that occur
in response to sensory stimulation. George Dawson developed an
average technique to increase the signal/noise ratio, which allows
this technique to be widely used for both clinical diagnosis and basic
research ( 5 ). Current clinical applications usually involve stimulation
of the visual, auditory, or somatosensory system. Somatosensory
evoked potentials, for example, have been used during surgery as a
means to locate and protect sensitive brain areas. They can also
effectively be used to determine cortical ischemia during carotid
endarterectomy surgeries and for intraoperative mapping of the
sensory areas of the brain.
Extracellular single-unit recording was developed in the 1950s
and this technique has been used to record the fi eld potentials of
active single neurons in order to investigate fundamental questions
about the excitability of CNS dendrites ( 6, 7 ). They also have been
used to study the behaviorally related discharge patterns of CNS
neurons in the awake, moving animal (e.g., 8, 9 ). This chapter briefl y
introduces the basic procedures, required materials, and tools for
measuring EEG, EP, and extracellular single-unit signals and proves
some examples regarding how these techniques can be applied to
various animal models in vivo.

2. Materials

EEG . Many EEG amplifi ers are available in the market, some of
which are used for clinical diagnosis and others for animal research.
In our laboratory, we use a Comet XL Lab-based PSG system from
GRASS Technologies to study epilepsy (Fig. 1a ).
EP . An AxoClamp 2B amplifi er from Axon Instrument
(Fig. 1b -1) with HS-2A headstage (Gain: ×1 LU) is used to study
slow-pain responses by selective stimulation of peripheral C-fi bers.
Single-unit recording. We use A-M System (Model 1800,
Fig. 1c -1) for single-unit recording.

2.1. Electrophy-
siological Equipment

2.1.1. Amplifi er

An oscilloscope is used to constantly monitor the electrical signals
detected by the recording electrode and amplifi ed by the amplifi er
for the extracellular single-unit recordings from midbrain dopamin-
ergic neuron. The oscilloscope is used to monitor the action potential

2.1.2. Oscilloscope