Effect of lateral cervical cord lesions on the respiratory rhythm of anaesthetized, decerebrate cats after vagotomy.

1. The lateral cervical cord of vagotomized, anaesthetized cats was superficially lesioned at the C3 or the C7 level before or after midcollicular decerebration.2. These cord lesions eliminated the inhibition of diaphragmatic discharge caused by chest compression. Previous work (Remmers, 1973) indicates that this change can be attributed to loss of reflex inhibition of inspiratory activity by intercostal afferents, probably as a result of interruption of tracts ascending in the lateral columns.3. Decerebrate cats with bilateral cervical cord lesions displayed abnormal respiratory patterns, ranging from apnoea to apneusis.4. The results are consistent with the hypothesis that the lateral columns carry proprioceptive feed-back from intercostal mechanoreceptors which promotes rhythmic breathing in the anaesthetized decerebrate cat.