Brain's Central Switchboard: Neurons Function as Precise Movement 'Brakes'

Recent research from the University of Basel and the Friedrich Miescher Institute for Biomedical Research has revealed that neurons located deep within the brain play a dual role in movement control—both initiating and actively suppressing actions with remarkable accuracy. Published in Nature, the study focuses on the basal ganglia, particularly the Substantia Nigra pars reticulata (SNr), which was traditionally thought to mainly inhibit unwanted movements by acting as a brake. However, new findings demonstrate that SNr neurons operate as a dynamic signaling system, precisely timing when movements should start or stop.

The team conducted experiments on mice performing reaching tasks, observing that individual SNr neurons exhibit complex, highly specific activity patterns—turning their firing rates up or down depending on the phase of movement. This creates a sophisticated traffic light system within the brain, guiding complex, coordinated actions by finely tuning the balance between activation and inhibition. Manipulating SNr neurons with optogenetics confirmed their pivotal controlling role, as activating them could halt movements instantly.

These insights challenge previous simplistic models of basal ganglia function, which viewed it mainly as a continuous inhibitory system. Instead, the findings support a granular, movement-based coding system that manages even subtle motor actions. Understanding this precise control mechanism has significant implications for neurological disorders such as Parkinson’s disease, where this delicate balance is disrupted, leading to motor initiation difficulties.

Overall, this research advances our comprehension of how the brain orchestrates movement with exceptional finesse, opening potential pathways for targeted treatments of movement disorders.