Imaging of Brainstem Sites Involved in Cardiovascular Control

This chapter discusses how neuro-imaging of brainstem sites is involved in cardiovascular control. The maintenance of blood pressure within a relatively narrow physiological range is essential to ensure adequate perfusion of vital organs such as the brain. The virtue in using this maneuver is that the changes in heart rate and arterial pressure are well known, with the increase in arterial pressure being brought about by an increase in muscle sympathetic nerve activity (MSNA). During the static phase of the maneuver, in which the inspiratory pump muscles are quiescent and only the laryngeal constrictors are active, intrathoracic pressure changes because of the elastic recoil of the lungs and chest wall against the closed glottis. Bilateral increases in activity also occur in the rostral lateral medulla, with decreases occurring in the dorsomedial and caudal lateral medulla. In humans, the rostral ventrolateral medulla (RVLM) and caudal ventrolateral medulla (CVLM) are displaced dorsally by the large inferior olivary nuclei.