Striatal bilateral control of skilled forelimb movement

Area of Science:

• Neuroscience
• Motor Control
• Striatal Function

Background:

• Skilled motor behavior necessitates coordinated activity between brain hemispheres.
• The striatum, a key motor control center, utilizes distinct neuronal populations expressing D1 or D2 dopamine receptors for output.
• Understanding the specific roles of these D1 and D2 receptor-expressing spiny projection neurons (D1SPNs and D2SPNs) is crucial for deciphering motor control mechanisms.

Purpose of the Study:

• To investigate the distinct contributions of D1SPNs and D2SPNs to skilled forelimb movements in mice.
• To determine how manipulating D1SPN and D2SPN activity impacts motor kinematics and task performance.
• To examine changes in striatal neuronal connectivity following motor skill acquisition.

Main Methods:

• Mice were trained on a reaching and grasping task involving a single food pellet.
• Optogenetic techniques were used to inhibit or excite D1SPNs and D2SPNs.
• Forelimb trajectory, task efficiency, and target accuracy were analyzed.
• Ex vivo electrophysiology was employed to compare striatal neuronal connectivity in naive versus trained mice.

Main Results:

• Inhibition and excitation of D1SPNs similarly disrupted ensemble dynamics, affecting overall kinematics.
• D2SPNs were found to play a specific role in controlling target accuracy.
• Electrophysiological analysis revealed strengthened striatal neuronal connectivity for ipsilateral D1 and contralateral D2 neurons after task practice.

Conclusions:

• Striatal D1SPNs and D2SPNs exhibit differential roles in motor control, with D1SPNs influencing overall movement dynamics and D2SPNs regulating accuracy.
• Motor skill acquisition leads to adaptive changes in striatal synaptic patterns, enhancing relevant neural pathways.
• Bihemispheric coordination and specific striatal output pathways are essential for smooth and efficient skilled motor execution.