[Respiratory modulation of startle reflexes in the cat].

Phasic respiratory influences on late reflex discharges in the limb and lower intercostal nerves--electrophysiological analogs of somesthetic and acoustic startle reflexes (SR)--were studied in unanesthetized (decerebrated) or chloralose-anesthetized cats. The integrated values of the SR in both types of nerves always essentially decreased during inspiratory phase (by 28-58% on the whole) compared to those during expiratory phase. Data obtained evidence that this respiratory modulation of the SR occurs mainly at the brainstem level. The modulation of the limb SR is presumably due to a suppression of the reflex transmission only during the inspiratory phase. Trends and temporal development of SR modulations during the whole respiratory cycle has shown that there are distinct differences in reticular mechanisms underlying the modulation in the limb and intercostal reflexes as well as in organization of the corresponding reticular centre.