Pre-synaptic facilitation of corticospinal output improves dexterity and finemotor control after stroke

In three monkeys with corticospinal tract lesions, thalamus-to-motor-cortex deep brain stimulation restored volitional arm and hand control, enabling unconstrained 3D reach and improved digit dexterity.

• Why it matters: CST damage after stroke leaves persistent weakness and loss of both gross and fine hand control, and effective therapies remain limited.
• What they did: The team used deep brain stimulation aimed at excitatory thalamocortical projections in monkeys with CST lesions, then assessed upper-limb movement, hand function, and digit control with behavioral testing and electrophysiology.
• The result: Stimulation facilitated upper-limb movements and improved strength, hand gross motor function, and digits control, with electrophysiology indicating benefits were mediated by and stronger when targeting fibers with monosynaptic connections to corticospinal motoneurons.

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