Stimulus-activated changes in brain tissue temperature in the anesthetized rat

LaManna, Joseph Charles; McCracken, Kimberly A.; Patil, Madhavi; Prohaska, O.

doi:10.1007/bf00999769

Cited by 83 publications

(69 citation statements)

References 25 publications

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“…Indeed, although, numerous experimental studies have demonstrated changes in the brain temperature of humans and animals upon functionally induced changes in brain activity, the magnitude and even sign of reported temperature changes vary substantially. For example, localized temperature variations from 0.01°C to 0.2°C were observed in animal brains (5)(6)(7)(8)(9)(10)(11)(12)(13) under different stimuli (visual, auditory, somatic). As reported in ref.…”

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confidence: 99%

Theoretical model of temperature regulation in the brain during changes in functional activity

Sukstanskiı̆

Yablonskiy

2006

Proc. Natl. Acad. Sci. U.S.A.

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The balance between metabolic heat production, heat removal by blood flow, and heat conductance defines local temperature distribution in a living tissue. Disproportional local increases in blood flow as compared with oxygen consumption during functional brain activity disturb this balance, leading to temperature changes. In this article we have developed a theoretical framework that allows analysis of temperature changes during arbitrary functional brain activity. We established theoretical boundaries on temperature changes and explained how these boundaries depend on physiology (blood flow and metabolism) and external (heat exchange with the environment) experimental conditions. We show that, in regions located deep in the brain, task performance should be accompanied by temperature decreases in regions where blood flow increases (activated regions) and by temperature increases in regions where blood flow decreases (deactivated regions). The sign of temperature effect may be reversed for superficial cortex regions, where the baseline brain temperature is lower than the temperature of incoming arterial blood due to the heat exchange with the environment. Importantly, due to heat conductance, the temperature effect is not localized to the activated region but extends to a surrounding tissue at rest over the distances regulated by the temperature-shielding effect of blood flow. This temperature-shielding effect quantifies the means by which cerebral blood flow prevents ''temperature perturbations'' from propagating away from the perturbed regions. For small activated regions, this effect also substantially suppresses the magnitude of the temperature response, making it especially important for small animal brains.brain temperature ͉ cerebral blood flow ͉ cerebral metabolism ͉ functional brain activity B asic mechanisms underlying global temperature regulation in humans and animals have attracted substantial attention from scientists, and considerable progress has been achieved in this area both in health and disease (see, e.g., refs. 1-4). However, information on brain temperature regulation, especially its relationship to function, is conflicting. Indeed, although, numerous experimental studies have demonstrated changes in the brain temperature of humans and animals upon functionally induced changes in brain activity, the magnitude and even sign of reported temperature changes vary substantially. For example, localized temperature variations from 0.01°C to 0.2°C were observed in animal brains (5-13) under different stimuli (visual, auditory, somatic). As reported in ref. 6, the sign of temperature response to visual stimulation in cats depends on the frequency of flashing light; for low frequencies (2-12 Hz), the temperature increases, whereas at high-frequencies (42-62 Hz) the temperature decreased. Negative temperature changes, on average Ϫ0.2°C, were observed in the deep regions of the visual cortex in conscious intact human subjects by a magnetic resonance method (14), whereas positive temperature changes up...

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confidence: 99%

Theoretical model of temperature regulation in the brain during changes in functional activity

Sukstanskiı̆

Yablonskiy

2006

Proc. Natl. Acad. Sci. U.S.A.

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“…• C can have long-term effect on tissue [LaManna et al 1989] and, in the extreme, death may even result from excessive tissue heating [Ruggera et al 2003]. …”

Section: Introductionmentioning

confidence: 99%

A Design and Analysis Framework for Thermal-Resilient Hard Real-Time Systems

Hettiarachchi

Fisher

Ahmed

et al. 2014

ACM Trans. Embed. Comput. Syst.

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We address the challenge of designing predictable real-time systems in an unpredictable thermal environment where environmental temperature may dynamically change (e.g., implantable medical devices). Towards this challenge, we propose a control-theoretic design methodology which permits a system designer to specify a set of hard-real-time performance modes under which the system may operate. The system automatically adjusts the real-time performance mode based on the external thermal stress. We show (via analysis, simulations, and a hardware testbed implementation) that our control-design framework is stable and control performance is equivalent to previous real-time thermal approaches, even under dynamic temperature changes. A crucial and novel advantage of our framework over previous real-time control is the ability to guarantee hard deadlines even under transitions between modes. Furthermore, our system design permits the calculation of a new metric called thermal resiliency which characterizes the maximum external thermal stress that any hard-real-time performance mode can withstand. Thus, our design framework and analysis may be classified as a thermal stress analysis for real-time systems.

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“…Thus, it has been proposed (Yablonskiy et al, 2000) that disproportional changes in cerebral metabolic rate of oxygen consumption ( ) 2 CMRO and CBF evoked by neuronal activity can explain the variation in brain tissue temperature (in the range of 0 0.2 C ± ) revealed by functional studies in humans (Yablonskiy et al, 2000;Shevelev et al, 1993;Gorbach et al, 2003) and animals (Trübel et al, 2006;Serota and Gerard, 1938;McElligot and Melzack, 1967;Melzack and Casey, 1967;Hayward and Baker, 1968;LaManna et al, 1989;Gorbach, 1993;Shevelev and Tsicalov, 1997;Shevelev, 1998).…”

Section: Introductionmentioning

confidence: 99%

From Blood Oxygenation Level Dependent (BOLD) Signals to Brain Temperature Maps

Sotero

Iturria-Medina

2011

Bull Math Biol

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A theoretical framework is presented for converting Blood Oxygenation Level Dependent (BOLD) images to temperature maps, based on the idea that disproportional local changes in cerebral blood flow (CBF) as compared with cerebral metabolic rate of oxygen consumption (CMRO 2 ) during functional brain activity, lead to both brain temperature changes and the BOLD effect. Using an oxygen limitation model and a BOLD signal model we obtain a transcendental equation relating CBF and CMRO 2 changes with the corresponding BOLD signal, which is solved in terms of the Lambert W function. Inserting this result in the dynamic bio-heat equation describing the rate of temperature changes in the brain, we obtain a non autonomous ordinary differential equation that depends on the BOLD response, which is solved numerically for each brain voxel. In order to test the method, temperature maps obtained from a real BOLD dataset are calculated showing temperature variations in the range: (-0.15, 0.1) which is consistent with experimental results. The method could find potential clinical uses as it is an improvement over conventional methods which require invasive probes and can record only few locations simultaneously. Interestingly, the statistical analysis revealed that significant temperature variations are more localized than BOLD activations. This seems to exclude the use of temperature maps for mapping neuronal activity as areas where it is well known that electrical activity occurs (such as V5 bilaterally) are not activated in the obtained maps. But it also opens questions about the nature of the information processing and the underlying vascular network in visual areas that give rise to this result.

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Stimulus-activated changes in brain tissue temperature in the anesthetized rat

Cited by 83 publications

References 25 publications

Theoretical model of temperature regulation in the brain during changes in functional activity

Theoretical model of temperature regulation in the brain during changes in functional activity

A Design and Analysis Framework for Thermal-Resilient Hard Real-Time Systems

From Blood Oxygenation Level Dependent (BOLD) Signals to Brain Temperature Maps

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