It has long been known that psychostimulant drugs have the paradoxical effect of reducing hyperactivity. [Psychostimulant drugs include methylphenidate – known by the trade names Ritalin, Concerta, and Methylin – and methamphetamine]. Since the mid-1950s, millions of children and adults have been prescribed stimulant medications to control attention deficit hyperactivity disorder (ADHD). But for more than seven decades, since the first experiment that gave an amphetamine drug to children diagnosed with behavioral problems, scientists have not known how stimulants work to control hyperactivity.
Now, a researcher at SUNY Downstate Medical Center, working with colleagues in Mexico, has identified the probable mechanism by which certain stimulants accomplish this paradoxical reduction of motor activity. David Erlij, MD, PhD, professor of physiology and pharmacology at SUNY Downstate, and fellow researchers have identified a network of nerve terminals where stimulation of dopamine D4 receptors depresses motor activity. “This network is localized deep in the brain, in the basal ganglia and the thalamus,” says Dr. Erlij, “and its responses explain the reduction in motor activity caused by psychostimulants.”
Source: Medical News Today