Injections of L-Dopa, the Precursor of Norepinephrine, Can Enable Spinally

question 67

Multiple Choice

Injections of L-dopa, the precursor of norepinephrine, can enable spinally transected cats to walk on a treadmill. The most likely explanation for this result is that

• A) norepinephrine stimulates spinal motor neurons, causing muscle contractions.
• B) norepinephrine acts on the neuromuscular junctions of the limb muscles and causes muscle contractions.
• C) norepinephrine activates sensory afferents that cause reflex muscle contractions in the limbs.
• D) norepinephrine activates the central pattern generator that causes rhythmic stepping motions.

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