Investigating the brain mechanisms of externally cued sit-to-stand movement in Parkinson's disease

Background: One of the more challenging daily-life actions for Parkinson’s disease patients is starting to stand from a sitting position. Parkinson’s patients are known to have difficulty with self-initiated movements and benefit from external cues. However, the brain processes underlying external cueing as an aid remain unknown. The advent of mobile EEG now enables the investigation of these processes in dynamic sit-to-stand movements.
Objective: To identify cortical correlates of the mechanisms underlying auditory cued sit-to-stand movement in Parkinson’s disease.
Methods: 22 Parkinson’s disease patients and 24 healthy age-matched participants performed self- initiated and externally cued sit-to-stand movements while cortical activity was recorded through 32-channel mobile EEG.
Results: Overall impaired integration of sensory and motor information can be seen in the Parkinson’s patients exhibiting less modulation in the theta band during movement compared to healthy age-matched controls. How Parkinson’s patients utilize external cueing of sit-to-stand movements can be seen in larger high beta power over sensorimotor brain areas compared to healthy controls, signaling sensory integration supporting the maintenance of motor output. This appears to require changes in cognitive processing allocation of cognitive resources to update the motor plan, reflected in frontal theta power increases in Parkinson’s patients when cued.
Conclusion: These findings provide the first neural evidence for why and how cueing improves motor function in sit-to-stand movement in Parkinson’s disease. The Parkinson’s patients’ neural correlates indicate that cueing induces greater activation of motor cortical areas supporting the maintenance of a more stable motor output, but involves the use of cognitive resources to update the motor plan.