I use primarily and almost exclusively maths and physics. I have not really go to the point yet where I actually need to exchange notes with a biologist or a neuroscientist. The reason being that the mathematical and physical foundations of what we are trying to do, are simply not there yet. And it will probably take some time before we can actually properly start talking to clinicians, and even patients, about how what we are doing can help them attain a better quality of life. But until then, it is only maths and physics and huge amount of programming.