Commentary to “Task activation results in regional 13 C-lactate signal increase in the human brain”

Abstract

Metabolism is fundamental to functional brain imaging. While functional MRI (fMRI) has greatly benefited neuroscience, ¹³C-MRS measures coupling between neuroenergetics and neurotransmission. However, a hyperpolarized ¹³C-MRI study in human brain shows increased ¹³C-lactate (i.e., cytosolic aerobic glycolysis) with no ¹³C-bicarbonate change (i.e., mitochondrial oxidation) within fMRI-defined activated areas. We discuss (dis)advantages of hyperpolarized vs. non-hyperpolarized ¹³C experiments and metabolic implications regarding the lactate increase: Is lactate a fuel for oligodendrocytes, astrocytes, or neurons? Is lactate a neuromodulator or a vasomodulator? Is lactate a byproduct of astrocytic glycogenolysis? Caveats aside, there is great enthusiasm for hyperpolarized ¹³C-fMRI.