Prolonged activation of soleus motoneurones following a conditioning train in soleus Ia afferents - A case for a reverberating loop?

In the decerebrate cat a short train of impulses in Ia afferents from the soleus muscle (or its synergists) may cause a long latency prolonged activity in the soleus muscle as judged by EMG and tension recording. The excitability increase may stay virtually constant during long periods (several minutes) but can be terminated at any time by a train of impulses in, for example, the peroneal nerve. It is suggested that the conditioning Ia impulses activate a neuronal circuit which can maintain a reverberating activity thereby causing the heightened excitability of the soleus motoneurones.