POWER SPECTRAL-ANALYSIS OF INSPIRATORY NERVE ACTIVITY IN THE ANESTHETIZED RAT - UNCORRELATED FAST OSCILLATIONS IN DIFFERENT INSPIRATORY NERVES

The spectral composition of the inspiratory nerve discharge was studie d in spontaneously breathing Sprague-Dawley rats under urethane (n = 7 ) or barbiturate (n = 10) anesthesia. Left phrenic nerve activity was recorded simultaneously with right phrenic or left recurrent laryngeal nerves. We found that all neurograms showed prominent fast oscillatio ns at common frequencies in the high frequency (HFO) range. Concurrent medium frequency oscillations (MFO) were present in inspiratory nerve discharges of four rats anesthetized with Nembutal. Significant coher ences between different nerves were uncommon (n = 2) and were only fou nd between HFOs. Thus although nerve autospectra were dominated by HFO , weak correlations indicated a relatively weak system HFO in the cent ral pattern generator, in the anesthetized rat.