The Baroreflex And Neurogenic Control Of Cerebral Autoregulation In Cerebral Blood Flow
type: CreativeWork
description: Introduction The neurogenic component of cerebral autoregulation (CA) refers to those mechanisms controlling cerebral blood flow under the influence of the nervous system, and which rely on the innervation of the cerebral blood vessels. The neurogenic control of CA is incompletely understood. Reports of a functional relationship between CA and the baroreflex (BR) have prompted suggestions that the baroreceptors might supply neurogenic input to the cerebral vasculature. Alternative potential inputs have also not been explored. A head up tilt (HUT) protocol offers an established way to investigate CA further. Near-infrared spectroscopy (NIRS) measurements during HUT provide an approach to characterising changes in the cerebral vasculature during orthostatic challenge. Inferences from HUT require knowledge of whether a hydrostatic correction must be applied to blood pressure (BP) measurements taken at heart level to convert them to BP at brain level. Whether such a correction is necessary is not fully understood. Methods Human subjects underwent HUT. Changes in heart rate, BP, cerebral blood flow and NIRS parameters were characterised. These variables were used to assess the appropriateness of hydrostatic correction. The measures were also used to calculate baroreceptor sensitivity (BRS) and CA index which were then compared using correlation techniques and Granger causality analysis. In the second set of experiments, subjects underwent a virtual reality simulation of HUT (VHUT) without gravitational change. Physiological variables were measured as before and responses during HUT and VHUT were compared. Results BP measured at heart level increased during HUT. Hydrostatic correction for BP at the level of the brain resulted in lower values. NIRS revealed an increase in cerebral blood volume which may occur predominantly within the venous compartment. There was no evidence to support a relationship between BRS and CA index. VHUT may result in some change within the cereb…
abstract: Introduction The neurogenic component of cerebral autoregulation (CA) refers to those mechanisms controlling cerebral blood flow under the influence of the nervous system, and which rely on the innervation of the cerebral blood vessels. The neurogenic control of CA is incompletely understood. Reports of a functional relationship between CA and the baroreflex (BR) have prompted suggestions that the baroreceptors might supply neurogenic input to the cerebral vasculature. Alternative potential inputs have also not been explored. A head up tilt (HUT) protocol offers an established way to investigate CA further. Near-infrared spectroscopy (NIRS) measurements during HUT provide an approach to characterising changes in the cerebral vasculature during orthostatic challenge. Inferences from HUT require knowledge of whether a hydrostatic correction must be applied to blood pressure (BP) measurements taken at heart level to convert them to BP at brain level. Whether such a correction is necessary is not fully understood. Methods Human subjects underwent HUT. Changes in heart rate, BP, cerebral blood flow and NIRS parameters were characterised. These variables were used to assess the appropriateness of hydrostatic correction. The measures were also used to calculate baroreceptor sensitivity (BRS) and CA index which were then compared using correlation techniques and Granger causality analysis. In the second set of experiments, subjects underwent a virtual reality simulation of HUT (VHUT) without gravitational change. Physiological variables were measured as before and responses during HUT and VHUT were compared. Results BP measured at heart level increased during HUT. Hydrostatic correction for BP at the level of the brain resulted in lower values. NIRS revealed an increase in cerebral blood volume which may occur predominantly within the venous compartment. There was no evidence to support a relationship between BRS and CA index. VHUT may result in some change within the cereb…
author: Vonberg, Frederick
keywords: Neurogenic Control, Cerebral Autoregulation
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/6bbac7aa-5304-4d37-8dff-63b329bfccf1/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2024-02
date modified: 2026-07-22T22:23:59Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.113743