Load effect on background rhythms during motor execution: A magnetoencephalographic study.
Takanobu Toyoshima1, Shogo Yazawa2, Takashi Murahara2
1Department of Neurology, School of Medicine, Sapporo Medical University, South 1, West 17, Chuo-ku, Sapporo 060-8556, Japan; Sapporo Shirakaba-dai Hospital, 2-18, Tsukisamu-higashi, Toyohira-ku, Sapporo 062-0052, Japan.
Adding load to self-paced finger movements minimally impacts pre-movement brain activity but significantly enhances post-movement brain synchronization, especially in the left hemisphere.
Area of Science:
- Neuroscience
- Motor Control
- Somatosensory System
Background:
- Cortical involvement in motor execution is crucial for voluntary movements.
- Understanding how external factors like load influence motor control is essential for rehabilitation and performance enhancement.
- Event-related desynchronization (ERD) and synchronization (ERS) are key neurophysiological markers of cortical activity during motor tasks.
Purpose of the Study:
- To investigate the impact of varying loads on cortical activity during self-paced index finger extension.
- To differentiate the effects of load on pre-movement versus post-movement cortical dynamics.
- To examine hemispheric differences in cortical responses to motor load.
Main Methods:
- Ten healthy, right-handed volunteers performed index finger extensions under three load conditions (0g, 50g, 100g) at self-paced intervals.
- Movement-related magnetic fields were recorded using magnetoencephalography (MEG).
- Analysis focused on event-related desynchronization (ERD) and synchronization (ERS) in the 18-23Hz frequency band, examining peak amplitude changes relative to baseline.
Main Results:
- Maximum cortical response was consistently observed in the left somatomotor area across all load conditions.
- No significant differences in pre-movement ERD were found among the three load conditions.
- Post-movement ERS was significantly greater for the 100g load compared to the 0g load, and more pronounced in the left hemisphere.
Conclusions:
- External load has a minimal effect on pre-movement cortical desynchronization during self-paced movements.
- Load significantly influences post-movement cortical synchronization, suggesting altered neural processing after movement completion.
- The findings highlight a load-dependent modulation of background cortical rhythms, with a greater effect observed in the left hemisphere, indicating its dominant role in processing motor load.
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