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The pattern of motor neuron activity can change the biochemical and functional properties of skeletal muscle cells. A. Muscle fibers have characteristic
metabolic, molecular, and electrical properties that identify them as "slow" (tonic) or "fast" (phasic) types. The micrograph on the right shows a section of
muscle tissue with histochemical staining for myosin ATPase. The middle sketch shows a section through the muscle, in which motor neurons (green and
brown) form synapses on a single type of muscle fiber. (Photo reproduced, with permission, from Arthur P. Hays.)
B. Motor neurons that connect with fast and slow muscle fibers (fast and slow motor neurons) exhibit distinct patterns of electrical activity: steady low
frequency (tonic)
for slow
and intermittent
high-frequency
bursts
(phasic)offorNeural
fast. Science, Fifth Editon
Source:
Formation
and Elimination
of Synapses,
Principles
C. Cross-innervation
experiments
showed JH,
thatJessell
some TM,
property
of the motor
neuron helps
to determine
whether
muscle
fibersFifth
are Editon;
fast or slow.
CrossCitation: Kandel
ER, Schwartz
Siegelbaum
SA, Hudspeth
AJ, Mack
S. Principles
of Neural
Science,
2012 Available
innervation was achieved
by
surgically
rerouting
fast
axons
to
slow
muscle
and
vice
versa.
Although
the
properties
of
the
motor
neurons
are
little
changed,
at: http://mhmedical.com/ Accessed: May 10, 2017
the properties
of the muscle
profoundly.
For example,
motor neurons induce fast properties in the slow muscle. (Adapted, with permission,
Copyright
© 2017change
McGraw-Hill
Education.
All rightsfast
reserved
from Salmons and Sreter 1976.)