The reciprocal relationship between short- and long-term motor learning and neurometabolites
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Introduction
Skill acquisition requires practice to stimulate neuroplasticity. Changes in inhibitory and excitatory neurotransmitters, such as respectively gamma-aminobutyric acid (GABA) and glutamate, are believed to play a crucial role in promoting neuroplasticity.
Methods
Magnetic resonance spectroscopy (MRS) at 3T, using the MEGA-PRESS sequence, and behavioral data were collected from 62 volunteers. Participants completed a four-week protocol, practicing either complex (n = 32) or simple (n = 30) bimanual tracking tasks (BTT). Neurotransmitter levels and skill levels at baseline, after two, and four weeks of motor training were compared for left and right primary sensorimotor cortex (SM1) and left dorsal premotor cortex (PMd). Furthermore, task-related modulations of neurotransmitter levels in left PMd were assessed.
Results
Baseline neurotransmitter levels in motor-related brain regions predicted training success. While lower GABA+ (p=0.0347) and higher Glx (glutamate+glutamine compound) levels (p=0.0234) in left PMd correlated with better long-term learning of simple and complex tasks, respectively, higher GABA+ in right SM1 correlated with complex task learning (p=0.0064). Resting neurometabolite levels changed during the intervention: left SM1 Glx decreased with complex training towards week 4 (p=0.0135), while right SM1 Glx was increased at week 2 (p=0.0043), regardless of training type. Group-level analysis showed no task-related neurometabolite modulation in the left PMd. However, individual baseline GABA+ and Glx modulation influenced short-term motor learning (interaction: p=0.0213).
Conclusion
These findings underscore the importance of an interplay between inhibitory and excitatory neurotransmitters during motor learning and suggest potential for future personalized approaches to optimize motor learning.
Key points
- Neurotransmitter dynamics predict training success: Baseline levels of GABA+ and Glx in motor-related brain regions (left PMd and right SM1) were found to predict long-term learning success, with specific patterns correlating with better performance in both simple and complex motor tasks.
- Training-induced changes in neurometabolites: Resting levels of Glx in SM1 changed significantly during the motor training, with a decrease in left SM1 Glx after four weeks of complex training, and an increase in right SM1 Glx after two weeks for both the simple and complex training group, indicating dynamic adaptations in response to motor training.
- Personalized motor learning potential: The interaction between baseline levels and task-related modulation of GABA+ and Glx influenced short-term motor learning outcomes.
