Figure 5. 5‐HT7 receptor blockade has no direct effect on motoneuron excitability, but alters sensory input to flexor motoneurons produced by plantar flexion of the hindlimb at the ankle joint.
A, the procedure for eliciting reflex EMG discharges in Sol and TA muscles (described in detail in the text). B–D, after SB269970 the activity produced during dorsi‐flexion of both Sol and TA was relatively unaffected by the drug (compare B, C and D), showing the absence of a direct effect of the drug on motoneuron excitability, whereas the reflex response in TA to plantar flexion was reversibly abolished (compare B, C and D). Abbreviations: rSol, right soleus muscle; rTA, right tibialis anterior muscle.