Glucose metabolism echoes long-range temporal correlations in the human brain

Area of Science:

• Neuroscience
• Metabolic Imaging
• Systems Biology

Background:

• Intrinsic brain activity exhibits scale-invariant dynamics characterized by long-range temporal correlations.
• The metabolic underpinnings of these persistent neural dynamics at the individual level are not well understood.

Purpose of the Study:

• To investigate the relationship between long-range temporal correlations in resting-state brain activity and glucose metabolism.
• To elucidate the specific metabolic pathways associated with these brain dynamics.

Main Methods:

• Integration of resting-state functional Magnetic Resonance Imaging (fMRI) and dynamic [18F]FDG Positron Emission Tomography (PET) data.
• Quantification of long-range temporal correlations using the Hurst exponent.
• Full kinetic modeling of [18F]FDG PET data to assess glucose metabolism.

Main Results:

• A systematic relationship was found between the Hurst exponent and glucose metabolism.
• Higher long-range temporal correlations in brain activity were associated with increased energetic demands and glucose metabolism.
• The association was specifically linked to intracellular glucose phosphorylation, indicating a direct link to neuronal energy metabolism.

Conclusions:

• Persistent temporal dependencies in intrinsic brain activity incur a measurable metabolic cost.
• Brain glucose metabolism, particularly intracellular phosphorylation, supports these scale-invariant neural dynamics.
• Continuous biosynthetic processes, like protein synthesis, may also contribute to sustaining these dynamics, potentially explaining a portion of the brain's 'Dark Energy'.