Laura,
“Numerous experiments show that the loss of dopamine from the basal ganglia increases inhibitory output from the habitual control circuits”
I happen to be a control engineer and the article sighted makes some sense to me.
Any man made dynamic system (for example the control system driving a rocket) must include a feed forward signal defining the immediate goal for movement (intention) AND a feed back signal quantifying the actual movement achieved. In engineering terms the feed back signal is used to attenuate and correct the feed forward signal (i.e. inhibitory and it is typically called a negative feed back signal). Of course this happens in a continuous manner in infinitesimal small steps.
The science of man made control systems essentially aims at smooth movement by manipulating the feed back signal.
For example, too much negative feed back signal will make movement sluggish. Too little (negative feedback) may result in uncontrolled or oscillatory movement.
This is a simplified picture and hope it helps.
Imad