Received September 26, 2006
Revised October 23, 2006
Accepted after revision November 23, 2006

¹ Dartmouth Medical School

^* To whom correspondence should be addressed. E-mail: walter.m.stjohn{at}dartmouth.edu.

	Abstract

High frequency oscillations may be signatures of the basic mechanisms underlying the neurogenesis of various patterns of automatic ventilatory activity. These high frequency oscillations in phrenic activity differ greatly in eupnea and gasping, implying different mechanisms of neurogenesis. In a decerebrate, in situ preparation of the rat, the peak frequency of high frequency oscillations fell in apneusis following removal of the rostral pons. Following removal of all pons, phrenic discharge had a mixed pattern of gasps and multiple bursts; some of the latter were incrementing, as in eupnea. Regardless of pattern, peak frequencies were significantly below those which were found during eupnea, apneusis or gasping of the decerebrate preparation. Results do not support the concept that "non gasping" rhythmic patterns that can be recorded following a removal of pons are generated by the same mechanisms as those generating eupnea. Indeed, both pons and medulla appear essential for all aspects of eupnea to be expressed.

Key Words: Brainstem, Respiration, Respiratory control

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