scholarly journals Exhaustive Exercise Attenuates the Neurovascular Coupling by Blunting the Pressor Response to Visual Stimulation

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yuji Yamaguchi ◽  
Tsukasa Ikemura ◽  
Naoyuki Hayashi
Keyword(s):  
Blood Flow ◽  
Visual Stimulation ◽  
Pressor Response ◽  
Neurovascular Coupling ◽  
Transcranial Doppler Ultrasound ◽  
Mean Value ◽  
Exhaustive Exercise ◽  
Maximal Heart Rate ◽  
Eyes Closed ◽  
Relative Change

Neurovascular coupling (NVC) is assessed as an increase response to visual stimulation, and is monitored by blood flow of the posterior cerebral artery (PCA). To investigate whether exhaustive exercise modifies NVC, and more specifically, the relative contributions of vasodilatation in the downstream of PCA and the pressor response on NVC, we measured blood flow velocity in the PCA (PCAv) in 13 males using transcranial Doppler ultrasound flowmetry during a leg-cycle exercise at 75% of maximal heart rate until exhaustion. NVC was estimated as the relative change in PCAv from the mean value obtained during 20-s with the eyes closed to the peak value obtained during 40-s of visual stimulation involving looking at a reversed checkerboard. Conductance index (CI) was calculated by dividing PCAv by mean arterial pressure (MAP) to evaluate the vasodilatation. At exhaustion, PCAv was significantly decreased relative to baseline measurements, and the PCAv response to visual stimulation significantly decreased. Compared to baseline, exhaustive exercise significantly suppressed the increase in MAP to visual stimulation, while the CI response did not significantly change by the exercise. These results suggest that exhaustive exercise attenuates the magnitude of NVC by blunting the pressor response to visual stimulation.

scholarly journals Neurovascular coupling and cerebral autoregulation in atrial fibrillation

2019 ◽  
Vol 40 (8) ◽  
pp. 1647-1657 ◽  
Author(s):  
Rehan T Junejo ◽  
Igor D Braz ◽  
Samuel JE Lucas ◽  
Johannes J van Lieshout ◽  
Aaron A Phillips ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Cerebral Artery ◽  
Cerebral Autoregulation ◽  
Visual Stimulation ◽  
Function Analysis ◽  
Neurovascular Coupling ◽  
Healthy Controls ◽  
Eyes Closed ◽  
Increased Risk ◽  
Transfer Function Analysis

The risk of cognitive decline and stroke is increased by atrial fibrillation (AF). We sought to determine whether neurovascular coupling and cerebral autoregulation are blunted in people with AF in comparison with age-matched, patients with hypertension and healthy controls. Neurovascular coupling was assessed using five cycles of visual stimulation for 30 s followed by 30 s with both eyes-closed. Cerebral autoregulation was examined using a sit–stand test, and a repeated squat-to-stand (0.1 Hz) manoeuvre with transfer function analysis of mean arterial pressure (MAP; input) and middle cerebral artery mean blood flow velocity (MCA Vm; output) relationships at 0.1 Hz. Visual stimulation increased posterior cerebral artery conductance, but the magnitude of the response was blunted in patients with AF (18 [8] %; mean [SD]) and hypertension (17 [8] %), in comparison with healthy controls (26 [9] %) ( P < 0.05). In contrast, transmission of MAP to MCA Vm was greater in AF patients compared to hypertension and healthy controls, indicating diminished cerebral autoregulation. We have shown for the first time that AF patients have impaired neurovascular coupling responses to visual stimulation and diminished cerebral autoregulation. Such deficits in cerebrovascular regulation may contribute to the increased risk of cerebral dysfunction in people with AF.

scholarly journals Effects of Long Chain Omega-3 Polyunsaturated Fatty Acids on Brain Function in Mildly Hypertensive Older Adults

Nutrients ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1413 ◽  
Author(s):  
Peter R. C. Howe ◽  
Hamish M. Evans ◽  
Julia C. Kuszewski ◽  
Rachel H. X. Wong
Keyword(s):  
Blood Flow ◽  
Brain Function ◽  
Corn Oil ◽  
Controlled Trial ◽  
Neurovascular Coupling ◽  
Transcranial Doppler Ultrasound ◽  
Omega 3 ◽  
Cerebrovascular Function ◽  
Randomised Controlled ◽  
Long Chain

Purported benefits of long chain omega-3 polyunsaturated fatty acid (LCn-3PUFA) for brain function may be attributable, at least in part, to improved cerebral perfusion. A pilot randomised controlled trial was undertaken to investigate effects of taking a DHA-rich fish oil supplement for 20 weeks on cerebrovascular function, mood and cognitive performance. Borderline hypertensives aged 40–85 years with low habitual LCn-3PUFA intake took four capsules/day of EPAX (1600 mg DHA + 400 mg EPA) or placebo (corn oil). Cerebrovascular function was assessed at baseline and after 20 weeks in 38 completers (19 on each supplement) using transcranial Doppler ultrasound of blood flow in the middle cerebral artery at rest and whilst performing a battery of cognitive tasks (neurovascular coupling). The primary outcome, cerebrovascular responsiveness (CVR) to hypercapnia, increased 26% (p = 0.024) in women; there was no change in men. In contrast, neurovascular coupling increased significantly (p = 0.01 for the overall response) in men only; the latter correlated with an increase of EPA in erythrocytes (r = 0.616, p = 0.002). There was no associated improvement of mood or cognition in either men or women. These preliminary observations indicate that LCn-3PUFA supplementation has the potential to enhance blood flow in the brain in response to both hypercapnic and cognitive stimuli. Future studies should examine differential effects of EPA and DHA and take account of the gender differences in responsiveness to supplementation.

scholarly journals Retinal Neurovascular Coupling in Diabetes

2020 ◽  
Vol 9 (9) ◽  
pp. 2829 ◽  
Author(s):  
Gerhard Garhöfer ◽  
Jacqueline Chua ◽  
Bingyao Tan ◽  
Damon Wong ◽  
Doreen Schmidl ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diabetic Retinopathy ◽  
Molecular Mechanisms ◽  
Visual Stimulation ◽  
Neurovascular Coupling ◽  
Neural Tissue ◽  
Current Evidence ◽  
Compelling Evidence ◽  
Functional Hyperemia ◽  
Patients With Diabetes

Neurovascular coupling, also termed functional hyperemia, is one of the physiological key mechanisms to adjust blood flow in a neural tissue in response to functional activity. In the retina, increased neural activity, such as that induced by visual stimulation, leads to the dilatation of retinal arterioles, which is accompanied by an immediate increase in retinal and optic nerve head blood flow. According to the current scientific view, functional hyperemia ensures the adequate supply of nutrients and metabolites in response to the increased metabolic demand of the neural tissue. Although the molecular mechanisms behind neurovascular coupling are not yet fully elucidated, there is compelling evidence that this regulation is impaired in a wide variety of neurodegenerative and vascular diseases. In particular, it has been shown that the breakdown of the functional hyperemic response is an early event in patients with diabetes. There is compelling evidence that alterations in neurovascular coupling precede visible signs of diabetic retinopathy. Based on these observations, it has been hypothesized that a breakdown of functional hyperemia may contribute to the retinal complications of diabetes such as diabetic retinopathy or macular edema. The present review summarizes the current evidence of impaired neurovascular coupling in patients with diabetes. In this context, the molecular mechanisms of functional hyperemia in health and disease will be covered. Finally, we will also discuss how neurovascular coupling may in future be used to monitor disease progression or risk stratification.

Hourly staircase sprinting exercise “snacks” improve femoral artery shear patterns but not flow-mediated dilation or cerebrovascular regulation: A pilot study

2020 ◽  
Author(s):  
Hannah G Caldwell ◽  
Geoff B Coombs ◽  
Hossein Rafiei ◽  
Philip N Ainslie ◽  
Jonathan P. Little
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Femoral Artery ◽  
Vascular Function ◽  
Regional Blood Flow ◽  
Cerebral Metabolism ◽  
Neurovascular Coupling ◽  
Duplex Ultrasound ◽  
Transcranial Doppler Ultrasound ◽  
Flow Mediated Dilation

Healthy males (n=10; 24±4 years; BMI: 24±2 kg/m2) completed two randomized conditions separated by ≥48 hours involving 6-8.5 hours of sitting with (“stair snacks”) and without (sedentary) hourly staircase sprint interval exercise (approx. 14-20 s each). Resting blood flow and shear rates were measured in the femoral artery, internal carotid artery, and vertebral artery (Duplex ultrasound). Flow-mediated dilation (FMD) was quantified as an index of peripheral endothelial function in the femoral artery. Neurovascular coupling (NVC; regional blood flow response to local increases in cerebral metabolism) was assessed in the posterior cerebral artery (transcranial Doppler ultrasound). Femoral artery hemodynamics were higher following the active trial with no change in the sedentary trial, including blood flow (+32±23% vs. -10±28%; P=0.015 and P=0.253, respectively), vascular conductance (+32±27% vs. -15±26%; P=0.012 and P=0.098, respectively), and mean shear rate (+17±8% vs. -8±28%; P=0.004 and P=0.310, respectively). The change in FMD was not different within or between conditions (P=0.184). Global cerebral blood flow (CBF), conductance, shear patterns, and NVC were not different within or between conditions (all P>0.05). Overall, exercise “stair snacks” improve femoral artery blood flow and shear patterns but not peripheral (e.g., FMD) or cerebral (e.g., CBF and NVC) vascular function following prolonged sitting. The study was registered at ClinicalTrials.gov (NCT03374436) Key findings: ● Breaking up 8.5 hours of sitting with hourly staircase sprinting exercise “snacks” improves resting femoral artery shear patterns but not flow-mediated dilation. ● Cerebral blood flow and neurovascular coupling were unaltered following 6 hours of sitting with and without hourly exercise breaks.

Neurovascular coupling is not influenced by lower body negative pressure in humans

2020 ◽  
Vol 319 (1) ◽  
pp. H22-H31
Author(s):  
Milena Samora ◽  
Lauro C. Vianna ◽  
Jake C. Carmo ◽  
Victor Macedo ◽  
Matthew Dawes ◽  
...  
Keyword(s):  
Blood Flow ◽  
Vertebral Artery ◽  
Cerebral Artery ◽  
Negative Pressure ◽  
Visual Stimulation ◽  
Posterior Cerebral Artery ◽  
Lower Body Negative Pressure ◽  
Neurovascular Coupling ◽  
Lower Body ◽  
Artery Blood Flow

Visual stimulation evoked a robust increase in posterior cerebral artery velocity and a modest increase in vertebral artery blood flow, i.e., neurovascular coupling (NVC), which was unaffected by lower body negative pressure in humans (LBNP). In addition, although LBNP induced a mild hypocapnia, this degree of hypocapnia in the absence of LBNP failed to modify the NVC response.

Cerebral blood flow velocity changes to visual stimuli in patients with multiple sclerosis

2002 ◽  
Vol 8 (3) ◽  
pp. 217-221 ◽  
Author(s):  
N Uzuner ◽  
S Özkan ◽  
D Gücüyener ◽  
G Özdemir
Keyword(s):  
Multiple Sclerosis ◽  
Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Visual Stimulation ◽  
Cerebral Blood Flow Velocity ◽  
Cerebral Arteries ◽  
Visual Stimuli ◽  
Occipital Cortex ◽  
Eyes Closed

We assessed the blood flow velocity (BFv) changes to visual stimuli using transcranial Doppler (TCD) in patients with multiple sclerosis (MS) during an exacerbation period by means of vasoneuronal coupling. Eighty-four patients (19 men, 75 women) and 45 healthy subjects (14 men, 31 women) were studied. Both posterior cerebral arteries (PCAs) were simultaneously monitored by TCD sonography during 10 cycles of 20 s eyes open observing complex moving visual images, and 20 s eyes closed at the end of every cycle. TCD sonography was performed at least at the first 2 days of exacerbation. Mean cerebral BFv throughout the procedure (p =0.003, p =0.001; right and left sides, respectively), velocity at rest (p =0.001, p <0.001), and velocity at stimulation (p =0.021, p =0.01) on both PCAs were significantly lower in patients than controls. However, BFv changes to visual stimulation on both sides were significantly higher in patients (p =0.01, p =0.031) compared to controls. There were negative correlations between P100 latencies and relative blood flow changes on both sides, but it was not significant on the left side. These results may suggest that patients with MS during exacerbation have more reactive vessels in the posterior circulation and/or more reactive neurons in the occipital cortex.

Cerebrovascular Response to Repetitive Visual Stimulation in Interictal Migraine with Aura

Cephalalgia ◽  
2004 ◽  
Vol 24 (9) ◽  
pp. 700-706 ◽  
Author(s):  
K Nedeltchev ◽  
M Arnold ◽  
M Schwerzmann ◽  
A Nirkko ◽  
F Lagger ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Transcranial Doppler ◽  
Blood Flow Velocity ◽  
Visual Stimulation ◽  
Cerebral Blood Flow Velocity ◽  
Cerebral Arteries ◽  
Transcranial Doppler Ultrasound ◽  
Healthy Controls ◽  
Cerebral Vasoreactivity

Cortical hypersensitivity and absent habituation to different stimuli have been observed in migraine patients. These features might also be transmitted to the cerebral vasoreactivity, but results are conflicting so far. Transcranial Doppler ultrasound (TCD) was used to assess cerebral blood flow velocity (CBFV) changes in the middle (MCA) and posterior cerebral arteries (PCA) in relation to repetitive checkerboard visual stimulation. Stimulation consisted of 10 consecutive cycles, each comprising 10 s stimulation and 10 s rest. TCD recordings were analysed using stimulus-related averaging algorithm. Data of 19 interictal migraineurs with aura were compared to those of 19 headache-free healthy volunteers. The CBFV increase in PCA and in MCA during visual stimulation was significantly larger and steeper in migraineurs than in controls ( P = 0.017 and P = 0.005). The response in PCA remained stable over the 10 stimulation cycles, both in migraineurs and in controls. The response in MCA was stable only in migraineurs. In controls it decreased over the last 5 stimulation cycles compared with the first 5 cycles ( P = 0.04). Migraineurs with aura exhibit a larger cerebrovascular response to repetitive visual stimulation compared to headache-free subjects. A reduced adaptation to environmental stimuli in migraine is suggested, since there was no habituation in migraineurs in contrast to healthy controls.

scholarly journals Reversal of neurovascular coupling in the default mode network: Evidence from hypoxia

2020 ◽  
pp. 0271678X2093082
Author(s):  
Gabriella MK Rossetti ◽  
Giovanni d’Avossa ◽  
Matthew Rogan ◽  
Jamie H Macdonald ◽  
Samuel J Oliver ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Neuronal Activity ◽  
Motion Detection ◽  
Default Mode Network ◽  
Visual Stimulation ◽  
Neurovascular Coupling ◽  
Bold Response ◽  
Default Mode ◽  
Regional Specificity

Local changes in cerebral blood flow are thought to match changes in neuronal activity, a phenomenon termed neurovascular coupling. Hypoxia increases global resting cerebral blood flow, but regional cerebral blood flow (rCBF) changes are non-uniform. Hypoxia decreases baseline rCBF to the default mode network (DMN), which could reflect either decreased neuronal activity or altered neurovascular coupling. To distinguish between these hypotheses, we characterized the effects of hypoxia on baseline rCBF, task performance, and the hemodynamic (BOLD) response to task activity. During hypoxia, baseline CBF increased across most of the brain, but decreased in DMN regions. Performance on memory recall and motion detection tasks was not diminished, suggesting task-relevant neuronal activity was unaffected. Hypoxia reversed both positive and negative task-evoked BOLD responses in the DMN, suggesting hypoxia reverses neurovascular coupling in the DMN of healthy adults. The reversal of the BOLD response was specific to the DMN. Hypoxia produced modest increases in activations in the visual attention network (VAN) during the motion detection task, and had no effect on activations in the visual cortex during visual stimulation. This regional specificity may be particularly pertinent to clinical populations characterized by hypoxemia and may enhance understanding of regional specificity in neurodegenerative disease pathology.

Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation

2021 ◽  
pp. 1-16
Author(s):  
Alexander Yang Hui Xiang ◽  
Prashanna Khwaounjoo ◽  
Yusuf Ozgur Cakmak
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Visual Stimulation ◽  
Pupil Diameter ◽  
Parasympathetic Activity ◽  
Whole Body ◽  
Vagal Activity ◽  
Eyes Closed ◽  
Visual Flow ◽  
Visual Interactions

BACKGROUND: Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated. OBJECTIVE: This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter. METHODS: Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset. RESULTS: CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed. CONCLUSIONS: Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

Sign in / Sign up

Export Citation Format

Share Document