I reckon the meaning of ataxia (“lacking coordination”) could be applied to our brains. I know I have FA but I suspect my brain doesn’t. Not my functional brain anyway.
The phrase “Use it or lose it” comes from the fact that the story that we use only 10% of our brain’s capacity is a myth. All functional brain real estate is always used and if a spot isn’t needed anymore (i.e. an amputee wouldn’t be using the spot that previously powered movement in the amputated limb), other functions will soon move in instead.
That’s why we do physiotherapy and exercise – to build and maintain strength and balance, to practise movement that we’ll use elsewhere. That keeps our brains working at those functions.
An unused functional part doesn’t need to be lost forever though. We can train our brains. In fact, stroke victims have retrained their brains from scratch, crawling then walking. That’s the power of neuroplasticity.
If you want to be awe-struck by stories of how the functional brain can be retasked, read The brain that changes itself by Norman Doidge. It’ll inspire you to keep at your exercise, keep going to physiotherapy and if you’ve lapsed, start going again!