Testing for pre-synaptic and post-synaptic changes in the soleus H reflex pathway following selective muscle...

Muscle vibration does not affect post-synaptic excitability of the corresponding motoneuronal pool, the concurrent depression of the monosynaptic reflex resulting from a pre-motoneuronal block of Ia spindle afferents. Indeed (1) both homonymous and heteronymous soleus responses (to electrical stimulation of the posterior tibial nerve (TN) and femoral nerve (FN), respectively) are clearly depressed during selective vibration of the homologous muscle (namely soleus (S) or quadriceps (Q)), but remain completely unchanged during vibration of the heterologous muscle (i.e. Q or S); (2) the effectiveness of facilitatory conditioning of FN and TN Ia afferents, respectively on the S motoneuronal pool is definitely reduced during vibration of the homologous muscle (namely Q and S).