Inactivate Player

Could we use, let's say, pharmacological drugs to activate or inactivate brain cells?

Once in the lungs, bacteria may invade the spaces between cells and between alveoli, where the macrophages and neutrophils (defensive white blood cells) attempt to inactivate the bacteria.

You can think of channelrhodopsin as a sort of light sensitive switch that can be artificially installed in brain cells so that now we can use that switch to activate or inactivate the brain cell simply by clicking it, and in this case we click it on with pulses of light.