Spontaneous synchronized neural activity in decerebrate gallamine-paralysed cats

In decerebrate cats paralysed with gallamine, over a period of several days there develops a remarkable synchronization of discharge in widely different motor nerves throughout the body, including intercostal nerves and limb nerves. These discharges are also in synchrony with slow waves approximately 100 ms in duration in the inferior olive. The slow waves and discharges are at first irregular and only weakly synchronized, but become increasingly strongly synchronized and by about the fourth day exhibit a strong 6-8 Hz rhythm. The degree of synchronization is greater the lower the end-tidal CO2 concentration. Transection of the spinal cord at a high cervical level breaks the synchrony and may abolish the discharge in the nerves, but the slow waves in the inferior olive continue rhythmically. It was shown, however, that gallamine injected subdurally at cervical vertebra 7 or lumbar vertebra 7 has a direct excitatory action on the spinal cord. Slow waves in the inferior olive are elicited by gallamine in the decerebrate, spinalized and decerebellectomized cat, and therefore must originate in the brainstem. Gallamine is known to act directly on olivary neurons and the slow waves may originate in the inferior olive, but further experiments are needed to determine what other structures it affects. The condition of the cat a few days after decerebration and paralysis resembles the clinical condition of reticular reflex myoclonus and it is suggested that the genesis of the myoclonus may be similar in the two conditions.