Cooperativity in Distributed Respiratory and Cardiovascular-Related Brainstem Neural Assemblies: Insights from Many-Neuron Recordings

Abstract

Baroreceptor stimulation causes a decline in respiratory frequency and tidal volume [16]. The brainstem mechanisms that mediate these changes are not well understood [2, 3, 16]. Neurons distributed in the nucleus tractus solitarius and both midline and ventrolateral regions of the medulla have been implicated in the regulation of breathing and cardiovascular control [1–5, 12, 13, 15, 18]. Our working hypothesis is that the bulbospinal projections that control the muscles of breathing and the sympathetic innervation of the cardiovascular system are regulated by a shared, dynamically organized, distributed neural network. The study of emergent network properties and processes requires the ability to represent the state (e.g., degree of synchrony) of subsets of neural assemblies as they interact. Traditional methods lack the spatial and temporal resolution needed for this task. In this preliminary report, we describe the use of many-neuron recordings and quantitative analytical methods to detect and evaluate functional connectivity and cooperative behavior among brainstem cardiorespiratory neurons. The data obtained with this approach support the hypothesis that a distributed neural network in the midline of the medulla contributes to both the stability of the breathing pattern and to changes in that pattern associated with altered baroreceptor activity.

This research was supported by NIH grant NS 19814.