How to Measure the Oxygen Production of Algi in the Brain

In our study, we injected algi into the blood vessels of a tadpole. We're working on these animals, after utilizing them and isolating the brain from these animals. Afterwards, measured the production of oxygen upon illumination of the tissue. Now when you turn off the light, it goes down to zero again. First the algie don't produce oxygen any more, and the brain is starting to consume all the oxygen that the algie have produced. And does that mean that, if you wanted to, you could turn the light up and down on a dimmer switch, and really find tun controll how much oxygen the brain is getting?