Energetic basis of brain activity: implications for neuroimaging.
Level 5 - mechanism / opinion, no new human data
Narrative review of neuroimaging and metabolic physiological literature
PubMed 15271497 · doi:10.1016/j.tins.2004.06.005
What was done
Narrative synthesis of in vivo magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI) literature examining cerebral energy consumption, glucose oxidation pathways, and neurotransmitter (glutamate and GABA) cycling.
What was found
The human brain accounts for approximately 2% of body mass but approximately 20% of body oxygen consumption. In the resting awake state, approximately 80% of brain energy consumption supports neuronal firing and the cycling of glutamate and GABA neurotransmitters. Task-related stimulation produces comparatively small changes in neuronal activity over this high baseline.
Why it matters
Contextualizes functional neuroimaging signals by demonstrating that task-related activations reflect minor metabolic perturbations superimposed on a massive baseline of ongoing cerebral activity.
Limits
Narrative review design without systematic search methodology or meta-analytic data. No specific sample sizes, demographic details, or statistical error bounds are provided in the abstract.
Cited by
- supports Approximately 80% of brain energy consumption is dedicated to glutamatergic neurotransmission.