<s>[INST] Which of the following statements is TRUE regarding alpha and gamma motor neurons During light activity, alpha motor neurons are activated first; during heavy activity, gamma motor neurons are activated first. b. Alpha motor neurons are activated before gamma motor neurons. c. Alpha and gamma motor neurons are activated at the same time. d. During light activity, gamma motor neurons are activated first; during heavy activity, alpha motor neurons are activated first. e. Gamma motor neurons are activated before alpha motor neurons. [/INST] Answer e) is correct. During active stretch excitation of gamma efferent neutrons of anterior gray column of spinal cord produces contraction of polar regions of the intro fugal fibers and there by not contractile equatorial regions of nuclear bag and chain fibers are actively stretched. This results in excitation of alpha motor neurons through the monosynaptic loop of stretch reflex consequently the extra fugal fibers of the corresponding muscle are contracted until it shortens to equal with the degree of contraction of muscle spindle. This method of contraction of skeletal muscle maintains its residual length. The alpha and gamma motor neurons are excited simultaneously by the pyramidal tract, the alpha neurons being the fast conductors initiate muscle contraction without limit of shortening and the gamma neurons through the reflex loop maintain muscle contraction with desired length. </s>