From Science Daily News, an encouraging report that some sessions breathing extra oxygen may selectively restore brain function damaged by a stroke, even a couple years later. A hyperbaric chamber delivering oxygen to the lungs at a higher pressure, supplies extra energy to the circulating blood. This has been used to treat sports injuries. The extra energy is helpful to brain tissue too.
Summarizing what I read, the brain is said to burn twenty percent of the body 's energy even though only about a tenth of the brain's neurons are busy firing at any one time. Neurons that need repair take even more energy. The thinking appears to be that there just isn't enough reserve energy in the blood supply to take on the repair job at the same time as the general operations of the brain. The treatment results in increased blood flow to many parts of the brain. This does't sound scary or invasive.
The colourized MRI has a lot of information. The third quadrant shows the percentage improvement in blood flow to different parts of the brain after the enhanced oxygen treatment. There's no negative change and zero to twenty five percent improved flow elsewhere.
Link to the original story: "Dr. Shai Efrati of Tel Aviv University's Sackler Faculty of Medicine has found a way to restore a significant amount of neurological function in brain tissue thought to be chronically damaged -- even years after initial injury".