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A model of brain circulation and metabolism: NIRS signal changes during physiological challenges.

Banaji M, Mallet A, Elwell CE, Nicholls P, Cooper CE - PLoS Comput. Biol. (2008)

Bottom Line: These quantities are now frequently measured in clinical settings; however the relationship between the measurements and the underlying physiological events is in general complex.We anticipate that the model will play an important role in helping to understand the NIRS signals, in particular, the cytochrome signal, which has been hard to interpret.The comparisons are encouraging, showing that the model is able to reproduce observed behaviour in response to various stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Essex, Colchester, United Kingdom. m.banaji@ucl.ac.uk

ABSTRACT
We construct a model of brain circulation and energy metabolism. The model is designed to explain experimental data and predict the response of the circulation and metabolism to a variety of stimuli, in particular, changes in arterial blood pressure, CO(2) levels, O(2) levels, and functional activation. Significant model outputs are predictions about blood flow, metabolic rate, and quantities measurable noninvasively using near-infrared spectroscopy (NIRS), including cerebral blood volume and oxygenation and the redox state of the Cu(A) centre in cytochrome c oxidase. These quantities are now frequently measured in clinical settings; however the relationship between the measurements and the underlying physiological events is in general complex. We anticipate that the model will play an important role in helping to understand the NIRS signals, in particular, the cytochrome signal, which has been hard to interpret. A range of model simulations are presented, and model outputs are compared to published data obtained from both in vivo and in vitro settings. The comparisons are encouraging, showing that the model is able to reproduce observed behaviour in response to various stimuli.

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Summary of the main inputs, variables and processes in the model.Model inputs are enclosed in solid ovals, while outputs are enclosed indashed ovals. Pa is arterial blood pressure,SaO2 is arterial oxygen saturation level, PaCO2 is arterialCO2 level. TOS and ΔoxCCO are NIRS signals defined inthe text.
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pcbi-1000212-g001: Summary of the main inputs, variables and processes in the model.Model inputs are enclosed in solid ovals, while outputs are enclosed indashed ovals. Pa is arterial blood pressure,SaO2 is arterial oxygen saturation level, PaCO2 is arterialCO2 level. TOS and ΔoxCCO are NIRS signals defined inthe text.

Mentions: The basic structure of the model is illustrated in Figure 1. In order to aid model validation, asmaller mitochondrial model appropriate to in vitro situationswill also be introduced later. In particular this model omits all processesrelating to blood flow, with oxygen being supplied directly to the mitochondria.


A model of brain circulation and metabolism: NIRS signal changes during physiological challenges.

Banaji M, Mallet A, Elwell CE, Nicholls P, Cooper CE - PLoS Comput. Biol. (2008)

Summary of the main inputs, variables and processes in the model.Model inputs are enclosed in solid ovals, while outputs are enclosed indashed ovals. Pa is arterial blood pressure,SaO2 is arterial oxygen saturation level, PaCO2 is arterialCO2 level. TOS and ΔoxCCO are NIRS signals defined inthe text.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2573000&req=5

pcbi-1000212-g001: Summary of the main inputs, variables and processes in the model.Model inputs are enclosed in solid ovals, while outputs are enclosed indashed ovals. Pa is arterial blood pressure,SaO2 is arterial oxygen saturation level, PaCO2 is arterialCO2 level. TOS and ΔoxCCO are NIRS signals defined inthe text.
Mentions: The basic structure of the model is illustrated in Figure 1. In order to aid model validation, asmaller mitochondrial model appropriate to in vitro situationswill also be introduced later. In particular this model omits all processesrelating to blood flow, with oxygen being supplied directly to the mitochondria.

Bottom Line: These quantities are now frequently measured in clinical settings; however the relationship between the measurements and the underlying physiological events is in general complex.We anticipate that the model will play an important role in helping to understand the NIRS signals, in particular, the cytochrome signal, which has been hard to interpret.The comparisons are encouraging, showing that the model is able to reproduce observed behaviour in response to various stimuli.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, University of Essex, Colchester, United Kingdom. m.banaji@ucl.ac.uk

ABSTRACT
We construct a model of brain circulation and energy metabolism. The model is designed to explain experimental data and predict the response of the circulation and metabolism to a variety of stimuli, in particular, changes in arterial blood pressure, CO(2) levels, O(2) levels, and functional activation. Significant model outputs are predictions about blood flow, metabolic rate, and quantities measurable noninvasively using near-infrared spectroscopy (NIRS), including cerebral blood volume and oxygenation and the redox state of the Cu(A) centre in cytochrome c oxidase. These quantities are now frequently measured in clinical settings; however the relationship between the measurements and the underlying physiological events is in general complex. We anticipate that the model will play an important role in helping to understand the NIRS signals, in particular, the cytochrome signal, which has been hard to interpret. A range of model simulations are presented, and model outputs are compared to published data obtained from both in vivo and in vitro settings. The comparisons are encouraging, showing that the model is able to reproduce observed behaviour in response to various stimuli.

Show MeSH