Ensemble Dynamics of Stellate Ganglion Neurons Reveal Differential Transduction of Cardiac and Pulmonary Inputs ‐ SPARC

Abstract

Background The sympathetic nervous system exerts closed‐loop hierarchical control of cardiac function partially through peripheral sympathetic ganglia (PSGs). To what extent PSGs possess network processing capabilities useful for local cardiopulmonary integration outside the central nervous system is unknown. Methods To understand whether neurons within PSGs process cardiopulmonary inputs, and to gain insights into the modes and properties of such transduction, we performed extracellular recordings (via a linear 16‐electrode array) to determine intrinsic activity of left stellate ganglion (LSG) neurons in chloralose‐anesthetized pigs (n=8). Continuous respiratory and left ventricular pressures (RP and LVP) were recorded along with the ECG. Neuronal activity was examined during resting states and under various cardiopulmonary stressors. Linkages between neural activity and LVP and RP were examined at the local neural ensemble and global population levels such that ensemble behavior could be examined over short time scales (minutes) versus evolution of population level processing over hours, using a sliding window. Results Neural ensembles show a wide range of regional behaviors with activity that may cease or commence during the cardiorespiratory cycle such that no neuron is either purely cardiac or pulmonary, rather neurons exhibit cardiopulmonary integration. Global level processing was examined, over a sliding window, for: (i) the presence or absence of cardiac and respiratory periodicities, and (ii) the evolution of the degree to which greater or lesser ‘attention’ is globally paid to LVP and RP relative to random sampling. The results of (ii) show that the greatest attention is paid to diastole and near‐peak LVP. Regarding RP, little attention is paid to the respiratory pressure while the breathing rate from (i) is generally strongly evident. Interestingly, spiking density did not correlate with level of attention i.e. increased spiking levels does not imply that random sampling has ceased and attention has become focused on LVP or RP. Conclusions Activity of stellate ganglion neurons recorded in situ reveal complex local neuronal and global population properties that are dynamically phase‐ and rate‐locked with cardiac and pulmonary function respectively. The combination of (i) and (ii) are useful in finding consistency in neuronal attention across animals since this combination gives insight into the degree to which a population of neurons is processing information at the local and global levels within PSGs. Support or Funding Information NIH: DP2OD024323‐01 and OT2OD023848