Dopamine freeze

From Yenra

New research from Northwestern University's Feinberg School of Medicine has revealed that dopamine strengthens and weakens the two primary circuits in the brain that control our behavior. This provides new insight into why a flood of dopamine can lead to compulsive, addictive behavior and too little dopamaine can leave Parkinson's patients frozen and unable to move.

These two main brain circuits help us decide whether to act out a desire or not. For example, do you get off the couch and drive to the store for icy beverages on a hot summer night, or just lie on the couch?

One circuit is a stop circuit that prevents you from acting on a desire; the other is a go circuit that provokes you to action. These circuits are located in the striatum, the region of the brain that translates thoughts into actions.

In the study, researchers examined the strength of synapses connecting the cerebral cortex, the region of the brain involved in perceptions, feelings and thought, to the striatum, home of the stop and go circuits that select or prevent action.

Scientists electrically activated the cortical fibers to simulate movement commands and boosted the natural level of dopamine. What happened next surprised them. The cortical synapses connecting to the go circuit became stronger and more powerful. At the same time, dopamine weakened the cortical connections in the stop circuit.

In the second part of the experiment, scientists created an animal model of Parkinson's disease by killing dopamine neurons. Then they looked at what happened when they simulated cortical commands to move. The result: the connections in the stop circuit were strengthened, and the connections in the go circuit were weakened.

Understanding the basis for these changes in brain circuitry moves scientists closer to new therapeutic strategies for controlling these brain disorders and other involving dopamine like schizophrenia, Tourette's syndrome and dystonia.