I would even add “Based on studies in mice, D1 receptors might make for better targets than D2 receptors”
That would be a welcome clarification.
my guess is this is like saying the odd registers on a chip are involved, vs the even registers. But it is actually hard to infer what the actually program running does, not to mention what bug in the program is causing the problem. But some substance deactivates the odd registers somehow without taking down the whole chip.