scholarly journals Brief anesthesia, but not voluntary locomotion, significantly alters cortical temperature

2015 ◽  
Vol 114 (1) ◽  
pp. 309-322 ◽  
Author(s):  
Michael J. Shirey ◽  
Jared B. Smith ◽  
D'Anne E. Kudlik ◽  
Bing-Xing Huo ◽  
Stephanie E. Greene ◽  
...  
Keyword(s):  
Blood Vessel ◽  
Computational Models ◽  
Brain Temperature ◽  
Core Body Temperature ◽  
Field Potential ◽  
Vessel Diameter ◽  
Two Photon Microscopy ◽  
Convolution Model ◽  
Cortical Temperature ◽  
The Brain

Changes in brain temperature can alter electrical properties of neurons and cause changes in behavior. However, it is not well understood how behaviors, like locomotion, or experimental manipulations, like anesthesia, alter brain temperature. We implanted thermocouples in sensorimotor cortex of mice to understand how cortical temperature was affected by locomotion, as well as by brief and prolonged anesthesia. Voluntary locomotion induced small (∼0.1°C) but reliable increases in cortical temperature that could be described using a linear convolution model. In contrast, brief (90-s) exposure to isoflurane anesthesia depressed cortical temperature by ∼2°C, which lasted for up to 30 min after the cessation of anesthesia. Cortical temperature decreases were not accompanied by a concomitant decrease in the γ-band local field potential power, multiunit firing rate, or locomotion behavior, which all returned to baseline within a few minutes after the cessation of anesthesia. In anesthetized animals where core body temperature was kept constant, cortical temperature was still >1°C lower than in the awake animal. Thermocouples implanted in the subcortex showed similar temperature changes under anesthesia, suggesting these responses occur throughout the brain. Two-photon microscopy of individual blood vessel dynamics following brief isoflurane exposure revealed a large increase in vessel diameter that ceased before the brain temperature significantly decreased, indicating cerebral heat loss was not due to increased cerebral blood vessel dilation. These data should be considered in experimental designs recording in anesthetized preparations, computational models relating temperature and neural activity, and awake-behaving methods that require brief anesthesia before experimental procedures.

scholarly journals Supportive or information-processing functions of the mature protoplasmic astrocyte in the mammalian CNS? A critical appraisal

2007 ◽  
Vol 3 (3) ◽  
pp. 181-189 ◽  
Author(s):  
Harold K. Kimelberg
Keyword(s):  
Information Processing ◽  
Blood Vessel ◽  
Critical Appraisal ◽  
Vessel Diameter ◽  
Synaptic Activity ◽  
Metabolic Substrates ◽  
Processing Properties ◽  
New Evidence ◽  
The Brain ◽  
Domain Concept

AbstractIt has been proposed that astrocytes should no longer be viewed purely as support cells for neurons, such as providing a constant environment and metabolic substrates, but that they should also be viewed as being involved in affecting synaptic activity in an active way and, therefore, an integral part of the information-processing properties of the brain. This essay discusses the possible differences between a support and an instructive role, and concludes that any distinction has to be blurred. In view of this, and a brief overview of the nature of the data, the new evidence seems insufficient to conclude that the physiological roles of mature astrocytes go beyond a general support role. I propose a model of mature protoplasmic astrocyte function that is drawn from the most recent data on their structure, the domain concept and their syncytial characteristics, of an independent rather than integrative functioning of the ends of each process where the activities that affect synaptic activity and blood vessel diameter will be concentrated.

Temperature Difference Between the Body Core and the Arterial Blood Supplied to the Brain During Hyperthermia or Hypothermia

2001 ◽  
Author(s):  
Liang Zhu ◽  
Maithreyi Bommadevara
Keyword(s):  
Blood Vessel ◽  
Temperature Difference ◽  
Carotid Arteries ◽  
Brain Temperature ◽  
Indirect Evidence ◽  
Blood Perfusion ◽  
The Body ◽  
Arterial Blood ◽  
Body Core ◽  
The Brain

Abstract In this study a theoretical model was developed to evaluate the temperature difference between the body core and the arterial blood supplied to the brain. Several factors including the local blood perfusion rate, blood vessel bifurcation in the neck, and blood vessel pairs on both sides of the neck were considered in the model. The theoretical approach was used to estimate the potential for cooling of blood in the carotid artery on its way to the brain by heat exchange with its countercurrent jugular vein and by the radial heat conduction loss to the cool neck surface. It shows that blood temperature along the common and internal carotid arteries typically decreases up to 0.86°C during hyperthermia. Selectively cooling the neck surface during hypothermia increases the heat loss from the carotid arteries and results in approximately 1.2°C in the carotid arterial temperature. This research could provide indirect evidence of the existence of selective brain cooling (SBC) in humans during hyperthermia. The simulated results can also be used to evaluate the feasibility of lowering brain temperature effectively by selectively cooling the head and neck surface during hypothermia treatment for brain injury or multiple sclerosis.

scholarly journals Relevance of Blood Vessel Networks in Blast-Induced Traumatic Brain Injury

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yi Hua ◽  
Shengmao Lin ◽  
Linxia Gu
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Blood Vessel ◽  
Vessel Diameter ◽  
Dynamic Responses ◽  
Brain Dynamics ◽  
Cerebral Vasculature ◽  
Vessel Networks ◽  
The Brain

Cerebral vasculature is a complex network that circulates blood through the brain. However, the role of this networking effect in brain dynamics has seldom been inspected. This work is to study the effects of blood vessel networks on dynamic responses of the brain under blast loading. Voronoi tessellations were implemented to represent the network of blood vessels in the brain. The brain dynamics in terms of maximum principal strain (MPS), shear strain (SS), and intracranial pressure (ICP) were monitored and compared. Results show that blood vessel networks significantly affected brain responses. The increased MPS and SS were observed within the brain embedded with vessel networks, which did not exist in the case without blood vessel networks. It is interesting to observe that the alternation of the ICP response was minimal. Moreover, the vessel diameter and density also affected brain dynamics in both MPS and SS measures. This work sheds light on the role of cerebral vasculature in blast-induced traumatic brain injury.

scholarly journals Brain surface temperature under a craniotomy

2012 ◽  
Vol 108 (11) ◽  
pp. 3138-3146 ◽  
Author(s):  
Abigail S. Kalmbach ◽  
Jack Waters
Keyword(s):  
Heat Loss ◽  
Brain Temperature ◽  
Core Body Temperature ◽  
Region Of Interest ◽  
Brain Structures ◽  
Network Function ◽  
Cranial Window ◽  
Brain Surface ◽  
And Function ◽  
The Brain

Many neuroscientists access surface brain structures via a small cranial window, opened in the bone above the brain region of interest. Unfortunately this methodology has the potential to perturb the structure and function of the underlying brain tissue. One potential perturbation is heat loss from the brain surface, which may result in local dysregulation of brain temperature. Here, we demonstrate that heat loss is a significant problem in a cranial window preparation in common use for electrical recording and imaging studies in mice. In the absence of corrective measures, the exposed surface of the neocortex was at ∼28°C, ∼10°C below core body temperature, and a standing temperature gradient existed, with tissue below the core temperature even several millimeters into the brain. Cooling affected cellular and network function in neocortex and resulted principally from increased heat loss due to convection and radiation through the skull and cranial window. We demonstrate that constant perfusion of solution, warmed to 37°C, over the brain surface readily corrects the brain temperature, resulting in a stable temperature of 36–38°C at all depths. Our results indicate that temperature dysregulation may be common in cranial window preparations that are in widespread use in neuroscience, underlining the need to take measures to maintain the brain temperature in many physiology experiments.

scholarly journals A Model for the Peak-Interval Task Based on Neural Oscillation-Delimited States

2018 ◽  
Author(s):  
Thiago T. Varella ◽  
Marcelo Bussotti Reyes ◽  
Marcelo S. Caetano ◽  
Raphael Y. de Camargo
Keyword(s):  
Computational Models ◽  
Field Potential ◽  
Response Patterns ◽  
Time Intervals ◽  
Repeated Presentation ◽  
Neuronal Ensembles ◽  
Biological Interpretation ◽  
Network Properties ◽  
The Brain ◽  
Local Field Potential Lfp

Specific mechanisms underlying how the brain keeps track of time are largely unknown. Several existing computational models of timing reproduce behavioral results obtained with experimental psychophysical tasks, but only a few tackle the underlying biological mechanisms, such as the synchronized neural activity that occurs through-out brain areas. In this paper, we introduce a model for the peak-interval task based on neuronal network properties. We consider that Local Field Potential (LFP) oscillation cycles specify a sequence of states, represented as neuronal ensembles. Repeated presentation of time intervals during training reinforces the connections of specific ensembles to downstream networks. Later, during the peak-interval procedure, these downstream networks are reactivated by previously experienced neuronal ensembles, triggering actions at the learned time intervals. The model reproduces experimental response patterns from individual rats in the peak-interval procedure, satisfying relevant properties such as the Weber law. Finally, we provide a biological interpretation of the parameters of the model.

scholarly journals Power Failure of Mitochondria and Oxidative Stress in Neurodegeneration and Its Computational Models

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 229
Author(s):  
JunHyuk Woo ◽  
Hyesun Cho ◽  
YunHee Seol ◽  
Soon Ho Kim ◽  
Chanhyeok Park ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Mitochondrial Dysfunction ◽  
Computational Models ◽  
Neuronal Damage ◽  
Living Organism ◽  
The Body ◽  
Mitochondrial Functions ◽  
A Cell ◽  
The Brain ◽  
And Oxidative Stress

The brain needs more energy than other organs in the body. Mitochondria are the generator of vital power in the living organism. Not only do mitochondria sense signals from the outside of a cell, but they also orchestrate the cascade of subcellular events by supplying adenosine-5′-triphosphate (ATP), the biochemical energy. It is known that impaired mitochondrial function and oxidative stress contribute or lead to neuronal damage and degeneration of the brain. This mini-review focuses on addressing how mitochondrial dysfunction and oxidative stress are associated with the pathogenesis of neurodegenerative disorders including Alzheimer’s disease, amyotrophic lateral sclerosis, Huntington’s disease, and Parkinson’s disease. In addition, we discuss state-of-the-art computational models of mitochondrial functions in relation to oxidative stress and neurodegeneration. Together, a better understanding of brain disease-specific mitochondrial dysfunction and oxidative stress can pave the way to developing antioxidant therapeutic strategies to ameliorate neuronal activity and prevent neurodegeneration.

scholarly journals Inferring brain-computational mechanisms with models of activity measurements

2016 ◽  
Vol 371 (1705) ◽  
pp. 20160278 ◽  
Author(s):  
Nikolaus Kriegeskorte ◽  
Jörn Diedrichsen
Keyword(s):  
Computational Models ◽  
Brain Activity ◽  
Visual Object ◽  
Visual Object Recognition ◽  
Summary Statistics ◽  
Activity Data ◽  
Individual Measurement ◽  
Activity Measurements ◽  
The Brain ◽  
The Way

High-resolution functional imaging is providing increasingly rich measurements of brain activity in animals and humans. A major challenge is to leverage such data to gain insight into the brain's computational mechanisms. The first step is to define candidate brain-computational models (BCMs) that can perform the behavioural task in question. We would then like to infer which of the candidate BCMs best accounts for measured brain-activity data. Here we describe a method that complements each BCM by a measurement model (MM), which simulates the way the brain-activity measurements reflect neuronal activity (e.g. local averaging in functional magnetic resonance imaging (fMRI) voxels or sparse sampling in array recordings). The resulting generative model (BCM-MM) produces simulated measurements. To avoid having to fit the MM to predict each individual measurement channel of the brain-activity data, we compare the measured and predicted data at the level of summary statistics. We describe a novel particular implementation of this approach, called probabilistic representational similarity analysis (pRSA) with MMs, which uses representational dissimilarity matrices (RDMs) as the summary statistics. We validate this method by simulations of fMRI measurements (locally averaging voxels) based on a deep convolutional neural network for visual object recognition. Results indicate that the way the measurements sample the activity patterns strongly affects the apparent representational dissimilarities. However, modelling of the measurement process can account for these effects, and different BCMs remain distinguishable even under substantial noise. The pRSA method enables us to perform Bayesian inference on the set of BCMs and to recognize the data-generating model in each case. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’.

Sign in / Sign up

Export Citation Format

Share Document