Submitted on October 25, 2007
Accepted on February 19, 2008
Differential modulation of neural network and pacemaker activity underlying eupnea and sigh breathing activities
Andrew K. Tryba1*, Fernando Pena2, Steven P. Lieske3, Jean Charles Viemari4, Muriel Thoby-Brisson5, and Jan-Marino Ramirez6
1 Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States; , United States
2 Departamento de Farmacobiologia, Cinvestav-Sede Sur, Mexico, Mexico D.F., Mexico
3 Department of Psychiatry, University of California San Francisco, San Francisco, California, United States
4 Laboratoire Plasticite et physio-pathologie de la motricite, CNRS, Marseille, France
5 Institut Alfred Fessard, NGI - CNRS, Gif sur Yvette, France; , France
6 Organismal Biology & Anatomy, The University of Chicago, Chicago, Illinois, United States
* To whom correspondence should be addressed. E-mail: atryba{at}mcw.edu.
Many networks generate distinct rhythms with multiple frequency and amplitude characteristics. The respiratory network in the pre-Botzinger complex (pre-Bot) generates both the low frequency, large amplitude sigh rhythm and a faster, smaller amplitude, eupneic rhythm. Could the same set of pacemakers generate both rhythms? Here we used an in vitro respiratory brainslice preparation. We describe a subset of synaptically isolated pacemakers that spontaneously generates two distinct bursting patterns. These two patterns resemble network activity including sigh-like bursts that occur at low frequencies and have large amplitudes and eupneic-like bursts with higher frequency bursts and smaller amplitudes. Cholinergic neuromodulation altered the network and pacemaker bursting: fictive sigh frequency is increased dramatically, while fictive eupneic frequency is drastically lowered. The data suggest that timing and amplitude characteristics of fictive eupneic and sigh rhythms are set by the same set of pacemakers that are tuned by changes in the neuromodulatory state.
