RESPIRATORY MOTOR-NERVE ACTIVITIES DURING EXPERIMENTAL SEIZURES IN CATS

We evaluated respiratory motor nerve activities during experimental se izures induced with subcortical penicillin. The activities of the phre nic (PH), nasolabial (NL), and hypoglossal (HG) nerves and the recurre nt laryngeal motor branches to the thyroarytenoid (TA) and posterior c ricoarytenoid (PCA) muscles were analyzed in 13 anesthetized, vagotomi zed, paralyzed, and ventilated cats. During ictal and interictal phase s of seizures, nerve activities became irregular and peak integrated n erve activities increased, particularly in the case of the PH nerve. T he ictal phase of seizures was associated with increased tonic activit y and decreased phasic respiratory discharges, particularly in the cas es of the HG, NL, and PCA nerves. During some prolonged ictal discharg es, entrainment of nerve activities by cortical spiking was associated with irregular uncoordinated activation, particularly in the TA nerve . These studies help explain respiratory impairment during seizures by providing evidence of impaired coordination between activation of mus cles that regulate upper airway patency and activation of the diaphrag m.