Aging is a natural process accompanied with a progressive deterioration of cognitive functions. With an aging population, more and more elderly people are suffering from cognitive impairment. Previous studies have paid more attention to the impact of inflammation and oxidative stress on cognitive function during aging. Recently, it has been discovered that neurovascular coupling (NVC), a mechanism regulating cerebral blood flow, may play a significant role in aging-related cognitive impairment. NVC responses regulate the supply of energy substances and oxygen during brain activity, which in turn enhances cognitive function. However, as people grow older, NVC responses gradually weaken, which may be one of the mechanisms underlying aging-induced cognitive impairment. Given the important role of NVC responses in the brain, it is necessary to search for intervention methods that can improve NVC responses and promote cognitive function. Exercise is an effective means to delay aging and improve cognitive function. It also has a certain promoting effect on NVC responses. This article reviews the regulatory mechanisms of NVC responses, the relationship between NVC responses and cognitive function, and explores the effects of aging and exercise intervention on NVC responses, hoping to provide new research ideas for exercise intervention to improve NVC responses and promote cognitive function in the elderly.
Humans ; Aged ; Neurovascular Coupling/physiology* ; Aging ; Cerebrovascular Circulation/physiology* ; Cognition ; Brain

Ischemia can cause decreased cerebral neurovascular coupling, leading to a failure in the autoregulation of cerebral blood flow. This study aims to investigate the effect of varying degrees of ischemia on cerebral hemodynamic reactivity using in vivo real-time optical imaging. We utilized direct cortical stimulation to elicit hyper-excitable neuronal activation, which leads to induced hemodynamic changes in both the normal and middle cerebral artery occlusion (MCAO) ischemic stroke groups. Hemodynamic measurements from optical imaging accurately predict the severity of occlusion in mild and severe MCAO animals. There is neither an increase in cerebral blood volume nor in vessel reactivity in the ipsilateral hemisphere (I.H) of animals with severe MCAO. The pial artery in the contralateral hemisphere (C.H) of the severe MCAO group reacted more slowly than both hemispheres in the normal and mild MCAO groups. In addition, the arterial reactivity of the I.H in the mild MCAO animals was faster than the normal animals. Furthermore, artery reactivity is tightly correlated with histological and behavioral results in the MCAO ischemic group. Thus, in vivo optical imaging may offer a simple and useful tool to assess the degree of ischemia and to understand how cerebral hemodynamics and vascular reactivity are affected by ischemia.
Animals ; Arteries ; Blood Volume ; Cerebrovascular Circulation ; Hemodynamics* ; Homeostasis ; Infarction, Middle Cerebral Artery* ; Ischemia ; Middle Cerebral Artery* ; Neurons ; Neurovascular Coupling ; Optical Imaging ; Rodentia* ; Stroke

In this paper a new type of cerebral circulation is introduced, including the basic principal, parameter algorithms and equipment design. The analyzer is developed on the basis of previous cerebral circulation analyzer and combined with the latest development of hemodynamics. It has the advantages of previous analyzer and overcomes its shortcomings frequently encountered in clinical that unable to finish the analysis without detection of all the intracranial vessels. It provides new functional module and adds indices such as hydraulic power, carotidshear stress, comprehensive index etc. This analyzer can be used for cerebral circulation dynamic analysis and auxiliary diagnosis of cerebrovascular diseases.
Algorithms ; Cerebrovascular Circulation ; Cerebrovascular Disorders ; diagnosis ; Equipment Design ; Hemodynamics ; Humans

Blood Pressure ; Cerebrovascular Circulation ; Circle of Willis ; Humans

In anesthetized normocapnic and normotensive dogs, the effect of arterial hypoxemia on cerebral blood flow and oxidative carbohydrate metabolism was studied. The results are as follows: 1) The hypoxic vasodilatory effect on cerevral vessels is intact even at profound systemic hypoxemia(Pao2 30 torr) if Paco2 is controlled within normal limits. 2) CMRO2 did not significantly increase above the normal even during profound arterial hopoxemis, indicating that CMRO2 levels are poor indices of hypoxia. 3) A disporportinately high glycolysis at Pao2 of 50 torr suggested early cerebral metabolic changes which became more marked with further decrease in Pao2. 4) One hour after restitution of normoxia, however, carebral blood flow and metabolism manifested complete recovery. 6) It is concluded that a transient(20 minutes) profoun systemic arterial hypoxemia does not produce prolonged disorder of cerebral blood flow and oxidative carbohydrate metabolism provided that the cerebral perfusion pressure is kept normal.
Animals ; Anoxia* ; Carbohydrate Metabolism ; Cerebrovascular Circulation* ; Dogs ; Glycolysis ; Metabolism*

Cerebrovascular Circulation ; physiology ; Humans ; Microcomputers ; Tomography, X-Ray Computed ; methods

BACKGROUNDThe feasibility of the mapping of quantitative cerebral blood flow (CBF) named flow-sensitive alternating inversion recovery exempting separate T1 measurement (FAIREST) is still controversial. This study aimed to evaluate the reliability of FAIREST in the measurement of regional CBF (rCBF) in healthy volunteers.

METHODSEighteen healthy volunteers underwent magnetic resonance (MR) scanning with the sequence of FAIREST. While they were at rest, rCBF values were obtained in various brain regions of interest (ROIs). The same scheme was repeated on every subject after two weeks. Statistical analysis was made to determine the effect of location, scan and side on the measurement of rCBF.

RESULTSThe mean CBF values were (122+/-28) ml x (100 g)(-1) x min(-1) and (43+/-10) ml x (100 g)(-1) x min(-1) in the gray and white matter respectively. There was significant main effect of location (t=-12.5, P<0.01), but no significant effect of side. Paired t-test of ROIs in the same slice showed no significant difference in most sites between two scans, except in the gray matter of the bilateral frontal lobes (t=2.18-2.34, P <0.05). However, the rCBF values of the same structure obtained from different slices showed a significant difference (t=-3.49, P<0.01).

CONCLUSIONFAIREST is a reliable technique in the measurement of rCBF, but different imaging slice may affect the agreement of rCBF across the scans.

OBJECTIVETo explore the mechanism of moxibustion at Zusanli (ST 36) and Xuanzhong (GB 39) treatment of ischemic apoplexy, and to evaluate the clinical therapeutic effect.

METHODSWith the design of sequential trial, the patients were divided into a treatment group and a control group. The treatment group were treated by addition with moxibustion at Zusanli (ST 36) and Xuanzhong (GB 39) on the basis of basic expectant treatment, once each day, for 20 consecutive days; and the control group with basic expectant treatment for 20 days. Changes of cerebrovascular functions before and after treatment were investigated by transcranial Doppler ultrasound (TCD) in the matched-pair's patients of ischemic apoplexy; the clinical therapeutic effect was assessed by nervous function defect before and after treatment.

RESULTSAll the test lines of the research targets reached to the effective margin the sequential trial figure, with a significant difference as compared with the control group (P < 0.05).

CONCLUSIONMoxibustion at Zusanli (ST 36) and Xuanzhong (GB 39) has good regulative action on cerebral vasomotorial response, auto-regulation of cerebral blood flow, and establishment of collateral circulation, and improves recovery nervous functions.

Arterial spin labeling (ASL) technique is a kind of perfusion functional magnetic resonance imaging method that is based on endogenous contrast, and it can measure cerebral blood flow (CBF) noninvasively. The ASL technique has advantages of noninvasiveness, simplicity and relatively lower costs so that it is more suitable for longitudinal studies compared with previous perfusion methods, such as positron emission tomography (PET), single photon emission computed tomography (SPECT), CT and the contrast agent based magnetic resonance perfusion imaging. This paper mainly discusses the current clinical applications of ASL in brain diseases as cerebrovascular diseases, brain tumors, Alzheimer's disease and epilepsy, etc.
Animals ; Brain Diseases ; diagnosis ; Brain Neoplasms ; diagnosis ; Cerebrovascular Circulation ; Cerebrovascular Disorders ; diagnosis ; Humans ; Magnetic Resonance Imaging ; methods ; Perfusion ; Spin Labels

BACKGROUND AND PURPOSE: External counterpulsation (ECP) is a noninvasive method used to enhance cerebral perfusion by elevating the blood pressure in ischemic stroke. However, the response of the beat-to-beat blood pressure variability (BPV) in ischemic stroke patients during ECP remains unknown. METHODS: We enrolled recent ischemic stroke patients and healthy controls. Changes in the blood flow velocities in bilateral middle cerebral arteries and the continuous beat-to-beat blood pressure before, during, and after ECP were monitored. Power spectral analysis revealed that the BPV included oscillations at very low frequency (VLF; <0.04 Hz), low frequency (LF; 0.04-0.15 Hz), and high frequency (HF; 0.15-0.40 Hz), and the total power spectral density (TP; <0.40 Hz) and LF/HF ratio were calculated. RESULTS: We found that ECP significantly increased the systolic and diastolic blood pressures in both stroke patients and controls. ECP decreased markedly the systolic and diastolic BPVs at VLF and LF and the TP, and the diastolic BPV at HF when compared with baseline. The decreases in diastolic and systolic BPV reached 37.56% and 23.20%, respectively, at VLF, 21.15% and 12.19% at LF, 8.76% and 16.59% at HF, and 31.92% and 23.62% for the total TP in stroke patients, which did not differ from those in healthy controls. The change in flow velocity on the contralateral side was positively correlated with the total TP systolic BPV change induced by ECP (r=0.312, p=0.035). CONCLUSIONS: ECP reduces the beat-to-beat BPV when increasing the blood pressure and cerebral blood flow velocity in ischemic stroke patients. ECP might be able to improve the clinical outcome by decreasing the beat-to-beat BPV in stroke patients, and this should be explored further in future studies.
Blood Flow Velocity ; Blood Pressure* ; Cerebrovascular Circulation* ; Counterpulsation* ; Humans ; Methods ; Middle Cerebral Artery ; Perfusion ; Stroke*