Spinal neurons specialized
for
scratching as opposed to swimming:
A substantial
minority (20/63)
of individual
neurons recorded in the spinal cord hindlimb enlargment gray matter
were
activated during scratching motor patterns but not during
swimming motor
patterns (right, A:
scratching, B:
swimming; IF = instantaneous frequency of this single
neuron; SU = single-unit; KE, HF, and HE are knee extensor, hip flexor, and hip
extensor
motor nerves, respectively; C shows that this neuron was most active
during the
hip extensor phase of scratching). Each such neuron tested (8/8) had
reduced
activity during swimming motor patterns (D).
These data demonstrate that some spinal cord interneuronal circuitry is
relatively specialized for generating scratching, as opposed to
swimming, motor
patterns. (From
Berkowitz, J. Comp.
Physiol. A 188:225-234,
2002)