MEDULLARY MECHANISMS OF RESPIRATORY CONTROL

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From studies of rhythmic behaviors such as walking, flying, swimming, and breathing, a common conceptual organization for the neuronal control of rhythmic movements has emerged. There is now nearly universal agreement that the basic motor pattern underlying rhythmic movements is produced by a network of neurons comprising a central pattern generator. The proposed project is a network, synaptic, and cellular analysis of mechanisms of pattern generation within the mammalian (guinea pig) respiratory system. The major question addressed is: what is the cellular and synaptic basis for generation of the mammalian respiratory rhythm? A combined electrophysiological and histological approach will be taken. The proposed experiments are divided into three major sections. First is characterization of the passive and active integrative properties of medullary neurons in regions of the brain stem known to be involved respiratory control. Second is a morphological analysis of structure of medullary neurons using intracellular staining techniques. Third is mapping and characterizing patterns of synaptic connectivity between medullary respiratory nucleic using multiple intracellular recording techniques. For these purposes we have developed an in vitro brain stem slice preparation and demonstrated the feasibility of multiple intracellular recording. The slice preparation provides an excellent opportunity to study electrical, morphological, and synaptic properties of medullary neurons at a cellular level not possible with other approaches. Such information will be extremely useful in evaluating current or future hypotheses for the cellular basis of pattern generation within the mammalian respiratory system and be of interest to the study of motor systems in general.