HELP nerve conduction experiment

Alan Chua achua at lynx.bc.ca
Wed Feb 19 20:19:28 EST 1997


Hi
	I need some help on this proposed lab experiment I will be
conducting.  The procedure is like this:  the subject wears a
recording electrode directly on the abductor digiti minimi muscle on
the arm.  This recording electrode is connected to a preamplifier and
then to the oscilloscope.  Stimulating electrodes are then placed,
first on the ulnar nerve between the radius and humerus at the elbow,
and then on the medial side of the wrist.  This stimulating electrode
is then connected to the trigger portion of the oscilloscope.  A
ground is placed in between the recording and stimulating electrode to
remove 60 hz interference.  The purpose of my experiment is to measure
the ulnar nerve conduction velocity by taking the distance between two
sites for stimulating electrode, and dividing this by the difference
in the latency period of the two sites (latency period is the period
beginning with stimulation and ending with the onset of the abductor
digiti minimi muscle contraction.

a few questions I would like answered are as follows:

what are 3 possible random error and 2 systematic sources of error for
my experiment?

what four components make up the latency between the beginning of the
stimulus and the beginning of the response? (eg travel distance,
musculature, etc)

Why does the EMG signal produced here different from a typical raw EMG
signal?

What is the purpose of the preamplifier connecting  the recording
electrode to the oscilloscope?

How can I ensure the electrical safety of the subject?  (eg remove
metal rings, move electrical sources away from subject, etc.)

My colleagues have suggested that I record the muscle activity instead
of the nerve fibers, why is this so?
						
To anyone who can improve my experimental procedure and answer my
inquries, thank you very much.

						achua at lynx.bc.ca



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