Abstract
Background
Research has shown that the learning of a novel motor task leads to neuroplastic changes in the central nervous system that are impacted by changes in sensorimotor integration. Individuals with Attention Deficit Hyperactive Disorder (ADHD) have marked reductions in cerebellar and cerebral grey matter volumes, which may suggest impaired sensorimotor integration. The ability to accurately match and grade force is heavily reliant on cerebellar function, suggesting that force matching accuracy could be impacted in those with ADHD. The purpose of this pilot study was to determine whether neural and behavioural changes can be seen following the learning of a novel force-matching task in healthy controls, with the goal of applying this paradigm to an ADHD population in future research.
Methods
Somatosensory evoked potentials (SEPs) were recorded in 6 healthy (age: 20.7 + 2.16) subjects after stimulating the median nerve of the right hand at 2.47 and 4.98 Hz frequencies pre- and post- motor learning. A force-matching task was performed using the abductor pollicis brevis (thumb) of their right hand. Individuals were provided augmented visual feedback throughout the task. Five phases of this force-matching task were administered, each containing four randomized blocks of force traces. Subjects returned 24-48 hours later to perform a retention task with visual feedback, and a transfer task with no visual feedback.
Results
The N9 SEP peak amplitude remained stable, validating the central changes. Increases in N18 and N30 SEP peak amplitudes were observed post motor-learning. The N24 and N60 SEP peak amplitudes remained stable post-motor learning. Performance accuracy improved in the post and retention phases when compared to baseline. Performance was less accurate during the transfer phase compared to retention, but participants still showed some transfer, indicating that motor learning occurred.
Conclusions
The findings from this study support the use of a novel-force matching task to observe neural and behavioural changes in ADHD populations. Further research is required to validate these findings.
