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The location of neurons generating the rhythm of breathing in mammals is unknown. By microsection of the neonatal rat brainstem in vitro, a limited region of the ventral medulla (the pre-Bötzinger Complex) that contains neurons essential for rhythmogenesis was identified. Rhythm generation was eliminated by removal of only this region. Medullary slices(More)
Three classes of neurons within the lateral tegmental field of the rat medulla having different target projections were identified by retrograde labelling with three different fluorescent tracers. Labelled bulbospinal premotor and propriobulbar interneurons of the ventral respiratory group and vagal motoneurons of nucleus ambiguus formed partially(More)
We present three hypotheses related to the nervous system control of breathing in mammals: 1) that neural mechanisms controlling breathing change with state and that the relationship between mechanisms in different states can be described in terms of either modulation or a basic transformation of properties, or both; 2) that the mechanisms generating(More)
An anatomic projection from the retrotrapezoid nucleus to the ventral respiratory group in cat was previously reported by our laboratory (J. C. Smith, D. E. Morrison, H. H. Ellenberger, M. R. Otto, and J. L. Feldman. J. Comp. Neurol. 281: 69-96, 1989). We now report on the properties of neurons in the retrotrapezoid nucleus, investigated with extracellular(More)
The termination patterns in the rat phrenic nucleus of neurons within two respiratory cell groups of the ventrolateral medulla (Bötzinger Complex and the rostral ventral respiratory group) were determined. The plant lectin, Phaseolus vulgaris leuco-agglutinin, was used as an anterograde tracer to label presynaptic processes of bulbospinal neurons, and(More)
The termination patterns of axons in the phrenic nucleus immunoreactive to synthetic enzymes for catecholamines and for serotonin and GABA were studied in rats. Spinal cord tissue in which phrenic motoneurons were retrogradely labeled with horseradish peroxidase was incubated with antisera against dopamine beta-hydroxylase,(More)
Brainstem projections to the phrenic nucleus were studied in rabbits using horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) as a retrograde and anterograde neuronal tracer. Injections of 1% WGA-HRP were centered in the phrenic nucleus in the C4-C5 ventral horn in 4 rabbits to identify pontomedullary nuclear groups that contain neurons(More)
Efferent and afferent connections of the dorsal and ventral respiratory groups in the medulla of the cat were mapped by axonal transport of wheat germ agglutinin conjugated to horseradish peroxidase. Injections of wheat germ agglutinin-horseradish peroxidase into the dorsal respiratory group and the three principal subdivisions of the ventral respiratory(More)
The pontomedullary connections of the rostral division of the ventral respiratory group (rVRG), the largest medullary population of inspiratory bulbospinal and propriobulbar neurons, were identified in the rat by retrograde and anterograde tracing techniques. These experiments revealed that: (i) the Kölliker-Fuse nucleus, portions of the medial and lateral(More)
The relationship of serotonergic neurons in raphe and ventrolateral medullary regions to neurons projecting to the rostral ventral respiratory group in the rat were investigated using combined immunohistochemical and retrograde labeling techniques. Serotonergic and non-serotonergic neurons retrogradely labeled with rhodamine beads were found intermingled in(More)