Multimodal exercises simultaneously stimulating cortical and brainstem pathways after unilateral corticospinal lesion

Area of Science:

• Neuroscience
• Motor Control Research
• Rehabilitation Science

Background:

• Corticospinal tract (CST) injury disrupts voluntary motor control.
• Brainstem pathways offer alternative motor pathways but are less consciously controlled.
• Strengthening spared neural pathways is crucial for recovery after CNS injury.

Purpose of the Study:

• To investigate if combined physical exercises targeting brainstem and CST pathways enhance motor function after CST injury.
• To test the hypothesis that simultaneous stimulation strengthens corticobulbar connections via Hebbian-like mechanisms.
• To evaluate behavioral and anatomical changes following multimodal training in mice with CST lesions.

Main Methods:

• Unilateral CST lesions were induced in mice (pyramidotomy).
• Mice underwent 4 weeks of training: brainstem (BS) exercises, CST exercises, simultaneous BS+CST exercises, or no training (NT).
• Skilled limb performance, gait kinematics, and corticobulbar/CST fiber density were assessed.

Main Results:

• Mice in the BS+CST group showed a trend towards improved skilled limb performance compared to other groups.
• No significant differences in gait kinematics were observed across training groups.
• Multimodal training did not significantly alter corticobulbar fiber density or CST collateral sprouting.

Conclusions:

• Simultaneous training of brainstem and CST pathways shows potential for improving skilled motor function after CST injury.
• Further research, including electrophysiological assessments, is needed to understand synaptic changes and optimize rehabilitation strategies.
• The study highlights the need for targeted interventions to enhance volitional control over residual motor pathways.