Yes this is true, but we actually have a lot more data to back this on than exclusively fMRI analysis - for example the ADHD medication guanfacine works only because the alpha 2 receptors happen to be wired differently in the prefrontal cortex than it is in other areas of the brain (a2 is inhibitory for most brain regions, but in the PFC they're positioned to amplify connections between neurons) , so by stimulating alpha 2 we allow for a more “top down” control from the prefrontal cortex than we do without, which improves executive function.

So that is one extremely robust way to understand neurological conditions like ADHD or Parkinson’s