Integrative physiological and computational approaches to understand autonomic control of cerebral autoregulation

Abstract

The brain requires steady delivery of oxygen and glucose, without which neurodegeneration occurs within minutes. Thus, the ability of the cerebral vasculature to maintain relatively steady blood flow in the face of changing systemic pressure, i.e., cerebral autoregulation, is critical to neurophysiologic health. Although the study of autoregulation dates to the early 20th century, only the recent availability of cerebral blood flow measures with high temporal resolution has allowed rapid, beat-by-beat measurements to explore the characteristics and mechanisms of autoregulation. These explorations have been further enhanced by the ability to apply sophisticated computational approaches that exploit the large amounts of data that can be acquired. These advances have led to unique insights. For example, recent studies have revealed characteristic time scales wherein cerebral autoregulation is most active, and specific regions wherein autonomic mechanisms are prepotent. However, given that effective cerebral autoregulation against pressure fluctuations results in relatively unchanging flow despite changing pressure, estimating the pressure-flow relationship can be limited by the error inherent in computational models of autoregulatory function. This review will focus on the autonomic neural control of the cerebral vasculature in health and disease from an integrative physiologic and perspective. It will also provide a critical overview of the current analytic approaches to understand cerebral autoregulation.

Deferoxamine, Cerebrovascular Hemodynamics, and Vascular Aging

“…While linear approaches can indicate an improvement (or deterioration) in cerebral autoregulation, nonlinearities may play an important role, and linear approaches may not be adequate to fully describe characteristics and effectiveness of cerebral autoregulation. 52;53 Thus, while we observed an improvement in cerebral autoregulation in older individuals after DFO infusion, future studies are needed to delineate exactly how DFO enhances vascular function in the brain.…”

Static autoregulation in humans: a review and reanalysis

“…In contrast, dynamic CA refers to the cerebral pressure-flow relationship observed during transient changes in arterial pressure (e.g., with changes in posture) and takes place over several seconds. Although the current study has focused on static CA, it should be noted that the physiological basis for differential mechanistic control between dynamic and static is unclear [1]. Likewise, in contrast to dynamic CA (reviewed in [5]), the physiological mechanisms underpinning static CA have been less studied and warrant further investigation.…”

“…Although the physiological underpinnings remain obscure [1], CA is characterized on a continuum ranging from static (steady-state) to dynamic (transient) components. Static CA is typically described as operating over several minutes to hours and represents the steady-state relationship between mean arterial pressure (MAP) and CBF [2].…”

Impaired Cerebral Autoregulation Is Associated With Vasospasm and Delayed Cerebral Ischemia in Subarachnoid Hemorrhage

“…However, although increased gain and reduced phase both indicate an impairment of cerebral auto-regulation, they are insufficient to tease apart physiological mechanisms of autoregulation. 27,28 …”