Neurovascular coupling responses and cognitive function: The impact of aging and the interventional effect of exercise / 生理学报

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.

Neurovascular coupling analysis of working memory based on electroencephalography and functional near-infrared spectroscopy / 生物医学工程学杂志

Working memory is an important foundation for advanced cognitive function. The paper combines the spatiotemporal advantages of electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) to explore the neurovascular coupling mechanism of working memory. In the data analysis, the convolution matrix of time series of different trials in EEG data and hemodynamic response function (HRF) and the blood oxygen change matrix of fNIRS are extracted as the coupling characteristics. Then, canonical correlation analysis (CCA) is used to calculate the cross correlation between the two modal features. The results show that CCA algorithm can extract the similar change trend of related components between trials, and fNIRS activation of frontal pole region and dorsolateral prefrontal lobe are correlated with the delta, theta, and alpha rhythms of EEG data. This study reveals the mechanism of neurovascular coupling of working memory, and provides a new method for fusion of EEG data and fNIRS data.

The Imaging of Localization Related Symptomatic Epilepsies: The Value of Arterial Spin Labelling Based Magnetic Resonance Perfusion

Accurate identification of the epileptogenic zone is an important prerequisite in presurgical evaluation of refractory epilepsy since it affects seizure-free outcomes. Apart from structural magnetic resonance imaging (sMRI), delineation has been traditionally done with electroencephalography and nuclear imaging modalities. Arterial spin labelling (ASL) sequence is a non-contrast magnetic resonance perfusion technique capable of providing similar information. Similar to single-photon emission computed tomography, its utility in epilepsy is based on alterations in perfusion linked to seizure activity by neurovascular coupling. In this article, we discuss complementary value that ASL can provide in the evaluation and characterization of some basic substrates underlying epilepsy. We also discuss the role that ASL may play in sMRI negative epilepsy and acute scenarios such as status epilepticus.

Cerebral Hemodynamics and Vascular Reactivity in Mild and Severe Ischemic Rodent Middle Cerebral Artery Occlusion Stroke Models

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.

Effect of alpha-7 nicotinic acetylcholine receptor activation on beta-amyloid induced recognition memory impairment. Possible role of neurovascular function

PURPOSE: To evaluate the effects of PHA-543613 (α7-nAChR agonist) and galantamine (acetylcholinesterase inhibitor (AChEI)) on recognition memory and neurovascular coupling (NVC) response in beta-amyloid (Aβ) 25-35-treated mice. METHODS: PHA-543613 (1 mg/kg, i.p.), and galantamine (3 mg/kg, s.c.), effects were tested in Aβ25-35 mice model of AD. α7-nAChR antagonist, methyllycaconitine (MLA) (1 mg/kg, i.p.), was used for evaluation of receptor blockade effects. Recognition memory in animals was assessed by the novel object recognition (NOR) task. NVC response was analyzed by laser-doppler flow meter in barrel cortex by whisker stimulation method. RESULTS: Both, PHA-543613 and galantamine improve recognition memory in Aβ-treated animals. However, the advantageous effects of PHA-543613 were significantly higher than galantamine. Also, pretreatment with MLA reversed both galantamine and PHA-543613 effects on NOR. Impaired NVC response in AD animals was improved by PHA-543613 and galantamine. However, MLA pretreatment disrupts this function. CONCLUSION: Activation of α7-nAChR improved recognition memory possible through enhancement of neurovascular response in Alzheimer's disease in animals.

The comparison of the effects of dexmedetomidine, fentanyl and esmolol on prevention of hemodynamic response to intubation / Comparação entre os efeitos de dexmedetomidina, fentanil e esmolol na prevenção da resposta hemodinâmica à intubação / Comparación entre los efectos de la dexmedetomidina, el fentanilo y el esmolol en la prevención de la respuesta hemodinámica a la intubación

Background and objectives: Laryngoscopy and intubation can cause hemodynamic response. Various medications may be employed to control that response. In this study, we aimed to compare the effects of dexmedetomidine, fentanyl and esmolol on hemodynamic response. Methods: Ninety elective surgery patients who needed endotracheal intubation who were in American Society of Anesthesiology I–II group and ages between 21 and 65 years were included in that prospective, randomized, double-blind study. Systolic, diastolic, mean arterial pressures, heart rates at the time of admittance at operation room were recorded as basal measurements. The patients were randomized into three groups: Group I (n = 30) received 1 μg/kg dexmedetomidine with infusion in 10 min, Group II (n = 30) received 2 μg/kg fentanyl, Group III received 2 mg/kg esmolol 2 min before induction. The patients were intubated in 3 min. Systolic, diastolic, mean arterial pressures and heart rates were measured before induction, before intubation and 1, 3, 5, 10 min after intubation. Results: When basal levels were compared with the measurements of the groups, it was found that 5 and 10 min after intubation heart rate in Group I and systolic, diastolic, mean arterial pressures in Group III were lower than other measurements (p < 0.05). Conclusions: Dexmedetomidine was superior in the prevention of tachycardia. Esmolol prevented sytolic, diastolic, mean arterial pressure increases following intubation. We concluded that further studies are needed in order to find a strategy that prevents the increase in systemic blood pressure and heart rate both. .

Justificativa e objetivos: Laringoscopia e intubação podem causar resposta hemodinâmica. Vários medicamentos podem ser usados para controlar essa resposta. Neste estudo, nosso objetivo foi comparar os efeitos de dexmedetomidina, fentanil e esmolol sobre a resposta hemodinâmica. Métodos: Foram incluídos no estudo prospectivo, randômico e duplo-cego 90 pacientes programados para cirurgias eletivas, com intubação endotraqueal, estado físico ASA I-II, entre 21 e 65 anos. Pressões arteriais médias, sistólicas, diastólicas e frequências cardíacas foram medidas ao darem entrada na sala de operações e registradas como valores basais. Os pacientes foram randomizados em três grupos: Grupo I (n = 30) recebeu 1 μg/kg de dexmedetomidina com infusão em 10 min; Grupo II (n = 30) recebeu 2 μg/kg de fentanil; Grupo III (n = 30) recebeu 2 mg/kg de esmolol 2 min antes da indução. Os pacientes foram intubados em 3 min. As pressões médias, sistólicas e diastólicas e as frequências cardíacas foram medidas antes da indução, antes da intubação e nos minutos 1, 3, 5 e 10 após a intubação. Resultados: Quando os níveis basais foram comparados entre os grupos, verificou-se que nos minutos 5 e 10 pós-intubação as frequências cardíacas no Grupo I e as pressões arteriais médias, sistólicas e diastólicas no Grupo III estavam mais baixas do que em outros tempos mensurados (p <0,05 ). Conclusões: Dexmedetomidina foi superior na prevenção de taquicardia. Esmolol preveniu o aumento das pressões arteriais médias, sistólicas e diastólicas após a intubação. Concluímos que estudos adicionais são necessários para descobrir uma estratégia que previna tanto o aumento ...

Justificación y objetivos: La laringoscopia y la intubación pueden causar una respuesta hemodinámica. Varios medicamentos pueden ser usados para controlar esa respuesta. En este estudio, nuestro objetivo fue comparar los efectos de la dexmedetomidina, el fentanilo y el esmolol sobre la respuesta hemodinámica. Métodos: Noventa pacientes programados para cirugías electivas con intubación endotraqueal, estado físico ASA I-II, y edades entre 21 y 65 años, se incluyeron en el estudio prospectivo, aleatorizado y doble ciego. Las presiones arteriales medias, sistólicas, diastólicas y las frecuencias cardíacas se midieron cuando los pacientes llegaron al quirófano y se registraron como valores basales. Los pacientes fueron aleatorizados en 3 grupos: el grupo i (n = 30) recibió 1 μg/kg de dexmedetomidina con infusión en 10 min; el grupo ii (n = 30) recibió 2 μg/kg de fentanilo; el grupo iii recibió 2 mg/kg de esmolol 2 min antes de la inducción. Los pacientes fueron intubados en 3 min. Las presiones medias, sistólicas y diastólicas y las frecuencias cardíacas fueron medidas antes de la inducción, antes de la intubación y durante los minutos 1, 3, 5 y 10 después de la intubación. Resultados: Cuando los niveles basales fueron comparados entre los grupos, verificamos que en los minutos 5 y 10 la postintubación, las frecuencias cardíacas en el grupo i y las presiones arteriales medias, sistólicas y diastólicas en el grupo iii eran más bajas que en otros tiempos medidos (p < 0,05). Conclusiones: La dexmedetomidina fue superior en la prevención de la taquicardia. El esmolol previno el aumento de las presiones arteriales medias, sistólicas y diastólicas después de la intubación. Concluimos que son necesarios algunos estudios adicionales para descubrir una estrategia ...