Hyperbaric Oxygenation Effects on Human Brain In Vivo: 1H MRS and Resting-State fMRI Study

Abstract

Previously using 31P magnetic resonance spectroscopy (MRS) we have demonstrated that one hyperbaric oxygenation (HBO) session (with O2 pressure 1.2 atm) directly activates cerebral energetics: the decrease in creatine phosphate (PCr) and, possibly, the increase in nicotinamide adenine dinucleotide. The aim of this study is to elucidate the effect of one HBO session on the concentrations of metabolites detectible by 1H MRS, and on the connectivity in Default Mode Network. Absolute concentrations of the metabolites were calculated. The reduction of N-acetyl aspartate by 3% was found in mediolateral prefrontal cortex (MPFC) with p < 0.05 and in posterior cingulate cortex (p < 0.1). The resting-state functional connectivity between these zones was elevated by ~ 40%, p < 0.05 after HBO session. Glutamate levels remained unchanged after HBO. There is an indication in support of lactate growth in MPFC after HBO session. The demonstrated metabolic changes, as well as the decrease in PCr shown in previous study, may signify the activation of power supply processes to compensate the energy expenses connected with the enhancement of cerebral functional connectivity even after one HBO session.