Age-related GABA- and glutamatergic differences in SMA during bimanual coordination

Area of Science:

• Neuroscience
• Motor Control
• Aging Research

Background:

• The Supplementary Motor Area (SMA) is crucial for bimanual coordination and complex motor control.
• Understanding age-related changes in SMA neurometabolites (GABA+ and Glx) and their impact on motor performance is limited.
• Neurometabolite alterations may underlie age-related declines in motor function.

Purpose of the Study:

• To investigate age-related differences in gamma-aminobutyric acid (GABA+) and glutamate + glutamine (Glx) levels within the SMA.
• To examine the relationship between these neurometabolites and bimanual motor performance across the adult lifespan.
• To explore task-related modulations of neurometabolites during a bimanual coordination task.

Main Methods:

• Magnetic Resonance Spectroscopy (MRS) was used to measure neurometabolite concentrations in the SMA.
• Participants included young adults and older adults performing a Bimanual Tracking Task (BTT).
• Neurometabolite levels were assessed during rest and task conditions.

Main Results:

• Younger adults outperformed older adults on the Bimanual Tracking Task.
• Older adults exhibited lower SMA GABA+ and Glx levels compared to young adults.
• No significant age-related differences were found in the GABA+/Glx ratio; task performance did not significantly alter metabolite levels.
• A lower GABA+/Glx ratio during the task was associated with better bimanual performance in older adults.

Conclusions:

• Neurometabolite concentrations in the SMA decrease with age, but the overall inhibitory-excitatory balance may be maintained.
• Task-specific neurometabolite changes were not observed.
• Reduced inhibitory tone (lower GABA+/Glx ratio) during motor tasks may be beneficial for bimanual coordination in older adults.