Dopamine brain cells linked directly to body’s ability to initiate movement
Using a recently developed technique called optogenetics, researchers have demonstrated in mice that the brain chemical dopamine plays a crucial role in enabling the body to initiate physical movement. This finding promises to help scientists develop a better understanding of how changes in the brain’s production of dopamine lead to specific motor - system symptoms in Parkinson’s disease and related movement disorders. The research was presented November 16 at Neuroscience 2014, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.
“It’s long been known that th e destruction of dopamine - producing neurons is a hallmark of Parkinson’s disease , but until now, the connection between the loss of those neurons and the inability to initiate movement , a symptom of Parkinson’s, wasn’t clear,” said Joaquim Alves da Silva o f the Champalimaud Center for the Unknown in Lisbon, Portugal. “Our research indicates that dopamine neurons are critical to initiate movement, thus supporting a link between the loss of these neurons and the decrease in motion associated with Parkinson’s disease.”
To study the role that dopamine plays in initiating movement, Alves da Silva and his colleagues turned to freely moving mice and a technology called optogenetics, which uses light to manipulate neurons with a genetically modified sensitivity to light. The researchers found that inhibiting dopamine neurons in a midbrain structure called the substantia nigra in freely moving mice increased the amount of time the animals took to initiate movement. Using the high temporal resolution of optogenetics , researchers could determine that this decrease in motion was due to an impairment in movement initiation without an increased tendency to stop or disturb ongoing movements. Conversely, activating dopamine neurons in mice when they were immobile promoted the animals’ movement.
Although the study involved healthy mice, the findings offer a new hypothesis for how dopamine changes may lead to motor - system symptoms in Parkinson’s disease and other movement disorders. This new understanding may provide insight into opportunities for treatment for the estimated 6.3 million people worldwide who have Parkinson’s disease, including 1 million living in the United States.