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Digital Image Processing and Three-Dimensional Reconstruction in the Basic Neurosciences
Published in Rangachar Kasturi, Mohan M. Trivedi, Image Analysis Applications, 2020
In one way or another, all neuroscience researchers seek answers to the question: How does the brain work? The most complex object in nature, a human brain, defines humans individually and as a species. In addition to its role in mentation and sensory processing, the brain plays important roles in regulating the health of the whole body. One example is its function as the topmost level of regulatory control in the endocrine system—the brain itself produces hormones that regulate the production of hormones generated by other tissues. The brain is capable of autoregulation as well. Since the brain requires a continuous and large (relative to other tissues) supply of oxygen and glucose for fuel, and since it can store no reserves of those substances, it adjusts the rate of transport of glucose across the blood-brain barrier and the rate of flow of the blood bringing the glucose and oxygen it needs. Blood flow and transport can be regionally up- or down-regulated, depending on the metabolic needs of the local tissues. Thus, in addition to the well-known structural complexity of the brain presented by neuroanatomy, the brain’s behavior as a consumer of energy and a processor of neurochemical information is likewise complex.
Acousto-Optic Cerebral Monitoring
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
Michal Balberg, Revital Pery-Shechter
The adequate perfusion of blood is regulated by the healthy brain in order to prevent situations where blood flow is higher or lower than needed for proper function (Czosnyka et al., 2009). However, when this autoregulation mechanism is compromised in the brain of patients suffering from traumatic brain injury, stroke, hypertension, or even under general anesthesia, it is crucial to continuously monitor the variations in cerebral blood flow (CBF) in order to manage and adjust cerebral perfusion. For example, recent clinical research using transcranial Doppler ultrasound (TCD) and optical assessment of cerebral autoregulation during cardio-vascular surgeries (Ono et al., 2012) has demonstrated that patients with impaired autoregulation are more likely than those with functional autoregulation to have perioperative stroke. The authors conclude that non-invasive monitoring of autoregulation may provide an accurate means to predict impaired autoregulation.
Kidney Structure and Physiology
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Joel M. Henderson and Mostafa Belghasem
Systemic arterial blood pressure varies throughout the day. Despite this, the perfusion pressure in the kidney is tightly regulated via several mechanisms to maintain the pressure gradient required to drive glomerular ltration at an optimal level. e glomerular capillary pressure driving ltration is dependent upon the upstream hemodynamic pressure in the renal arterial system, and the resistances imparted by the aerent and eerent arterioles. Contraction of the aerent arteriole increases the resistance proximal to the glomerulus, thereby reducing blood pressure within the glomerular capillaries. e resistance due to the contraction of the eerent arteriole raises the glomerular capillary blood pressure. ese two arterioles respond dierentially to various stimuli, as discussed below. e two most important mechanisms modulating glomerular capillary hemodynamics are autoregulation and tubuloglomerular feedback.
Cognition impairment of rat in undersea environment
Published in International Journal of Environmental Health Research, 2022
Yingxin Zou, Ying Tang, Wei Fan, Lina Liu, Yong Jiao
The cognitive changes might have primarily occurred due to two reasons, either there was a direct stimulus from the undersea environment or there was an activation of the brain plasticity as an adaptative mechanism to deal with the extreme environment. The regulation of CBF is an important, established way of controlling brain plasticity. It undergoes autoregulation, which is a dynamic response to protect the cerebral circulation from matching the need for constant blood supply and water homeostasis. CBF comprises of key physiologic processes that maintain optimum functioning of the neural activity. Cerebral hypoperfusion may attenuate the brain function, including the autonomic nervous system. The regulation of CBF also plays an efficient role in the preservation of cognitive function (Ogoh 2017), though an increase in CBF does not necessarily lead to cognitive benefits (Haskell-Ramsay et al. 2018). During diving, cetaceans cognitively control bradycardia and vasoconstriction to decrease cardiac output and organ perfusion, maintain blood pressure, and redistribute the flow of blood to the hypoxia-sensitive brain and heart (Elmegaard et al. 2016). A lower CBF was associated with poor cognition (Purkayastha et al. 2019), though its autoregulation was observed to be preserved in sympathetically and parasympathetically denervated animals indicating that it was not a major contributing factor in the extrinsic neurogenic regulation. There is an increase in CBF in case of improvement in neuronal activity when there is an increased cognitive demand for the metabolic substrate glucose and oxygen (Haskell-Ramsay et al. 2018).