Summary: New research shows that neurons in the basal ganglia do more than initiate movement—they also suppress it with striking precision. The study demonstrates that individual neurons in the Substantia Nigra pars reticulata (SNr) switch dynamically between activation and inhibition depending on the exact phase of a movement, a finding that challenges the traditional view of the basal ganglia as a simple “brake.”
SNr activity resembles a system of traffic signals: by selectively permitting or blocking specific muscle actions at precise moments, these signals allow complex behaviors to emerge from tightly timed combinations of “go” and “stop” commands. The results shed new light on motor control and have potential implications for treating disorders such as Parkinson’s disease, in which this balance is disrupted.
Key Facts:
- Dynamic signaling: Neurons in the SNr change their firing rates up or down depending on distinct movement phases such as reaching, grasping, or retracting.
- Traffic light model: Basal ganglia output appears to operate as a finely tuned control system that licenses or inhibits individual movements in real time.
- Therapeutic insight: Understanding the timing and specificity of these signals may guide improved therapies for movement disorders, including Parkinson’s disease.
Source: University of Basel
Neurons deep within the brain both enable and suppress movement—with exceptional specificity.
Researchers at the University of Basel and the Friedrich Miescher Institute for Biomedical Research (FMI) report these findings in Nature. Their experiments in mice reveal that the output neurons of the basal ganglia do not act solely as a tonic brake; instead, they produce temporally precise, movement-specific signals that either release or suppress downstream motor programs.
Simple acts—reaching for an apple or bringing a spoon to the mouth—depend on a complex neural choreography. The basal ganglia, a deep brain network, play a central role in organizing that choreography. Historically, many models described basal ganglia output as a continuous inhibitory influence over motor centers, briefly lifted when an action is allowed. While that “brake and release” idea explained some observations, it struggled to account for the fine-grained control needed during coordinated, multi-step movements.
Led by Professor Silvia Arber, the researchers recorded activity from SNr neurons while mice performed skilled forelimb actions. They discovered that SNr neurons display highly specific temporal patterns: many neurons alternated between increases and decreases in firing rate several times across a single behavioral sequence. Each neuron’s pattern corresponded to discrete movement components—such as the reach, grasp, or retraction—indicating a level of specificity beyond a global stop-or-go signal.
Basal ganglia: a precise switchboard
Instead of acting simply as a gate that lifts inhibition to permit movement, the SNr appears to operate like a collection of finely timed signals—each one permitting or suppressing a particular movement element. In this “traffic light” analogy, different SNr neurons turn green or red for distinct movements at specific times, allowing the brain to assemble complex behaviors from precisely controlled subcomponents.
Fine-grained movement control
Two doctoral students on the team recorded SNr activity while mice reached for food pellets. They found that some SNr neurons paused only during one precise movement phase, while others increased firing exclusively during another phase. Using optogenetics to manipulate SNr activity, the researchers demonstrated causal control: activating SNr neurons could block an ongoing action, confirming these neurons’ role in suppressing movement when required.
Even subtle changes in a movement led to distinct adjustments in SNr signaling. Downstream brainstem motor centers responded to those SNr patterns and, in turn, relayed signals that either facilitated or constrained motor output. This bidirectional interaction supports a model in which the basal ganglia output conveys detailed, movement-specific commands to sculpt behavior moment by moment.
Implications for movement disorders
The discovery of temporally precise, bidirectional signals in basal ganglia output reshapes our understanding of motor control mechanisms. It also points to new strategies for treating disorders such as Parkinson’s disease and chorea, where disrupted timing and balance of inhibition and activation produce characteristic motor symptoms, including difficulty initiating movements.
“By decoding how the basal ganglia normally coordinate movement, we can aim for interventions that restore the correct timing and specificity of these signals,” says lead researcher Silvia Arber. Targeted therapies that refine when and which circuits are suppressed or released may ultimately improve motor function in affected patients.
About this neuroscience research news
Author: Angelika Jacobs
Source: University of Basel
Contact: Angelika Jacobs – University of Basel
Image: The image is credited to Neuroscience News
Original research: Open access. “Dynamic basal ganglia output signals license and suppress forelimb movements” by Silvia Arber et al., published in Nature (DOI: 10.1038/s41586-025-09066-z).
Abstract
Dynamic basal ganglia output signals license and suppress forelimb movements
The basal ganglia are essential for motor control, and their dysfunction contributes to motor deficits. Prior work in primate oculomotor circuits suggested that movements arise from transient pauses in tonically active inhibitory basal ganglia output neurons that release brainstem motor centers. Yet, other studies have reported prominent increases in basal ganglia output during different motor tasks, challenging that simple model.
This study shows that in the mouse SNr, basal ganglia output neurons represent complex forelimb behavior through highly granular and dynamic spiking patterns that together tile task execution across the population. Single SNr neurons display movement-specific firing pauses and increases, each linked to precise and distinct forelimb movements. Combining optogenetics with simultaneous recordings from basal ganglia output and postsynaptic brainstem neurons, the authors demonstrate how these dynamic firing changes functionally release and suppress movements through downstream targets.
Overall, the results reveal highly specific, temporally precise movement representations within basal ganglia output circuitry and support a model in which SNr neurons dynamically provide bidirectional, movement-specific signals to downstream motor circuits for the release and suppression of motor programs.