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Evaluating the gray and white matter energy budgets of human brain function
Yuguo Yu1, Peter Herman2,3,4, Douglas L Rothman2,3,4,5
11 School of Life Science and the Collaborative Innovation Center for Brain Science, the Center for Computational Systems Biology, Fudan University, Shanghai, China.
Summary
Brain energy consumption is primarily for signaling in gray matter and nonsignaling in white matter. This study quantifies these costs, revealing lower signaling rates in human brains compared to rats.
Area of Science:
- Neuroscience
- Metabolic Imaging
- Biophysics
Background:
- Brain energy demands are crucial for function, but the allocation between signaling and nonsignaling processes remains debated.
- Glucose oxidation (CMRglc(ox)) is the main energy source, with its distribution in gray and white matter poorly understood.
Purpose of the Study:
- To quantify the energy budget for signaling and nonsignaling processes in gray and white matter.
- To compare energy consumption patterns between human and rat brains at a cellular level.
Main Methods:
- Combined metabolic measurements (PET, autoradiography, 13C-MRS) with theoretical bottom-up energy budget calculations.
- Utilized biophysical properties of neuronal/glial cells and species-specific electrophysiological/morphological data.
Main Results:
- Awake resting cortical signaling accounts for ~70% of CMRglc(ox), while nonsignaling processes account for ~30%.
- Nonsignaling energy demands dominate in white matter, contrasting with gray matter.
- Human cortical glutamatergic signaling rate (~1.2 Hz) is approximately 4 times lower than in rats.
Conclusions:
- Established conserved principles of brain energy allocation across species.
- Validated bottom-up energy budgets enable computation of CMRglc(ox) maps and cellular interpretation of metabolic imaging.
- Revealed significant differences in signaling energy costs between human and rat brains.
