Cerebellar Transcranial Alternating Current Stimulation: Frequency-Specific Modulation of Human Gait

Area of Science:

• Neuroscience
• Motor Control
• Human Locomotion

Background:

• Coordinated locomotion relies on rhythmic neural activity, with the cerebellum crucial for movement timing.
• The influence of cerebellar oscillations on human gait is not fully understood, limiting applications in motor learning and rehabilitation.
• Cerebellar transcranial alternating current stimulation (c-tACS) offers a potential tool to investigate and modulate cerebellar function.

Purpose of the Study:

• To investigate frequency-dependent effects of cerebellar transcranial alternating current stimulation (c-tACS) on human gait parameters.
• To test if gait-matched c-tACS enhances phase alignment and temporal gait characteristics.
• To determine if higher-frequency stimulation selectively modulates spatial gait parameters.

Main Methods:

• Fifteen healthy adults received randomized bilateral c-tACS at various frequencies (individual gait-cycle frequency, offsets, individual step frequency, alpha harmonic, 50 Hz, sham).
• Gait kinematics were recorded using head-mounted accelerometry during continuous walking and a stop-and-go task.
• Phase synchrony between stimulation and gait was quantified using the debiased phase-locking value (dPLV).

Main Results:

• 50 Hz c-tACS significantly increased gait velocity and stride length, selectively modulating spatial gait parameters without affecting cadence or stride time.
• Gait-matched stimulation (individual gait-cycle frequency, individual step frequency) demonstrated strong phase alignment with gait but did not improve temporal parameters compared to sham.
• Phase synchrony generally decreased with frequency offsets from individual gait-cycle frequency, with a transient increase during stop-and-go not specific to active stimulation.

Conclusions:

• Cerebellar transcranial alternating current stimulation exhibits frequency-dependent effects on human locomotion.
• High-frequency stimulation (50 Hz) can selectively enhance spatial gait parameters, suggesting distinct cerebellar roles in gait control.
• Findings refine mechanistic understanding of rhythmic cerebellar stimulation's interaction with gait, informing targeted neuromodulation strategies for rehabilitation.