Quantitative positron emission tomography reveals regional differences in aerobic glycolysis within the human brain

Abstract

Glucose and oxygen metabolism are tightly coupled in the human brain, with the preponderance of the brain's glucose supply used to generate ATP via oxidative phosphorylation. A fraction of glucose is consumed outside of oxidative phosphorylation despite the presence of sufficient oxygen to do so. We refer to this process as aerobic glycolysis. A recent positron emission tomography study reported that aerobic glycolysis is uniform within gray matter. Here, we analyze the same data and demonstrate robust regional differences in aerobic glycolysis within gray matter, a finding consistent with previously published data.

Keywords: Brain imaging; energy metabolism; glucose; metabolism; positron emission tomography.

Figure 1.

Differences in OGI between resting state networks. (a) Regions of interest for each of the seven resting state networks projected on the right hemisphere cortical gray matter surface of the Conte 69 atlas using Connectome Workbench. Images show the right lateral and medial surfaces. (b) Pairwise differences between each resting state network. Within each cell is the difference in OGI (ΔOGI) between resting state networks along with the 95% CI of the difference. Positive numbers indicate greater OGI (less AG) in the network listed on the vertical axis. Only significant differences are shown in color. The numbers along the bottom row are the mean and the 95% CI for each network. Network abbreviations: FPC: fronto-parietal control, DMN: default mode, DAN: dorsal attention, VAN: ventral attention; LAN: language; SMN: somatomotor; VIS: visual. (c) Within-subject comparison of OGI evaluated within the default mode network versus visual network. The solid blue lines connect regional measurements within a single participant. Note consistency of regional differences in OGI from subject to subject. The DMN exhibited lower OGI than the visual network (VIS) in every subject.

Figure 2.

Regional topography of OGI. (a) A group-averaged OGI map obtained from the authors of the Hyder et al. study. Regional differences are found throughout the brain. (b) Replication of Figure 3(a) from Hyder et al. shows little regional variation in OGI. Regional differences are masked by the use of a color scale that lacks a dynamic range which is not matched over the relevant physiologic range of the data.