Region-specific uncoupling of oxygen and glucose metabolism in the human cortex during visual stimulation
Year: 2024
Type: preprint
Abstract: The brain primarily relies on oxidative glucose metabolism; however, the oxygen-to-glucose index (OGI) has been suggested to decrease during neuronal activation. Direct evidence for this uncoupling is limited, as the cerebral metabolic rates of oxygen (CMRO₂) and glucose (CMRglc) have not been measured simultaneously in humans under different physiological conditions. We combined multiparametric quantitative BOLD (mqBOLD) imaging with functional PET (fPET) to quantify oxygen and glucose metabolism simultaneously during rest and visual stimulation in a single session. At rest, OGI in the visual cortex was approximately 4.6–5.0, consistent with predominantly oxidative metabolism. During stimulation, CMRglc and cerebral blood flow (CBF) increased, while oxygen extraction fraction (OEF) decreased. CMRO₂ rose only modestly, resulting in a 12% reduction in OGI within the visual cortex. Interestingly, this glycolytic shift extended across the wider cortex (∼8%), but through a different mechanism. While the visual cortex displayed increased CBF and CMRglc with reduced OEF, characteristic of aerobic glycolysis, the remaining cortex showed reduced CBF and CMRO₂ but maintained CMRglc. Our study demonstrates the feasibility of measuring the dynamics of both energy substrates simultaneously in the human brain and reveals a widespread, regionally heterogeneous shift in energy metabolism in response to stimulation. (196)
Language: English
Subfield: Radiology, Nuclear Medicine and Imaging
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W4403376232