Tracing Human Sympathetic Cardiovascular Control Mechanism in the Brain

We review our approach of using MSNA-coupled fMRI to identify how different regions of the brain interact to control blood pressure. By performing functional magnetic resonance imaging (fMRI) of the brain at the same time as recording muscle sympathetic nerve activity (MSNA), via a microelectrode in the common peroneal nerve, we can identify areas of the brain involved in the generation of sympathetic outflow to the muscle vascular bed, a major contributor to blood pressure regulation.

Together with functional connectivity analysis of areas identified through MSNA-coupled fMRI, we have established key components of the human sympathetic connectome and their roles in the control of blood pressure. Whilst our studies confirm the roles of nucleus tractus solitarius (NTS), caudal ventrolateral medulla (CVLM) and rostral ventrolateral medulla (RVLM) in the baroreflex-mediated control of MSNA, we have identified cortical areas - dorsolateral prefrontal cortex, precuneus and insula - that are coupled to RVLM via the hypothalamus and midbrain periaqueductal gray (PAG). This emphasizes the roles of areas above the brainstem in the regulation of blood pressure.