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Owner’s Guide
27
Using the Bio Amp
Standard electrophysiology texts describe how to record various types of biological
signal. ADInstruments also produces materials describing specific uses of Bio Amps,
such as Animal Physiology and Human Physiology LabChart experiments, that can be
downloaded from the ADInstruments website or obtained from your ADInstruments
representative.
Some Suitable Uses
The Bio Amp can measure a wide variety of biological signal sources. Some of these
measurements include:
ECG. Electrocardiogram (also referred to as EKG); a recording of surface potentials due
to electrical currents associated with the heartbeat.
EEG. Electroencephalogram; a recording of the electrical activity of the brain. Scalp
electrodes record potential waves (10–100 µV) representing the summed activity of
cortical neurons.
EMG. Electromyography; a recording of the electrical activity of a muscle, using surface
electrodes. The recorded activity may be a voluntary contraction, or evoked by motor
nerve stimulation.
EOG. Electro-oculogram; a recording of the potential diff erence between the front and
back of the eyeball, as projected on to the face. Only supported on Octal and Quad Bio
Amps (not supported on Single and Dual Bio Amps)
ERG. Electroretinogram; a recording of the electrical signals produced in the retina by a
light stimulus. Bilateral measurements require a Dual Bio Amp, or two Bio Amps.
Cortical Evoked Potentials. Averaged recordings of the electrical activity of the brain
when subject to stimulation: visual evoked response, auditory evoked response, and
somatosensory response. These should be done with signal averaging, using Scope
view.
SNAP. Sensory nerve action potential; a recording of evoked responses in stimulated
nerves. This is usually done with signal averaging, using Scope view.
Some Unsuitable Uses
The Single/Dual Bio Amp and Quad/Octal Bio Amp are not recommended for work
requiring high-impedance electrodes or using a high bandwidth. Some of the tasks for
which they are not really suitable include:
•
Intracellular micropipette recordings. Recordings from a very fine, electrolyte-
filled tube inserted into a nerve or muscle cell. These require an electrometer
amplifier.
•
Needle electromyography; the intramuscular recording of the electrical activity
of a muscle, which requires low input capacitance and a driven guard.
For these a headstage is required. The bandwidth is limited to approximately 5 kHz.