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Reflex myoclonus in cortical-basal ganglionic degeneration involves a transcortical pathway
A Strafella1, P Ashby, A E Lang
1Playfair Neuroscience Unit University of Toronto, Toronto Hospital, Ontario, Canada.
Summary
Short-latency reflex myoclonus in cortical-basal ganglionic degeneration (CBGD) involves exaggerated reflexes. This suggests a loss of cortical inhibitory mechanisms, impacting motor control.
Area of Science:
- Neuroscience
- Neurology
- Motor Control Research
Background:
- Cortical-basal ganglionic degeneration (CBGD) is a neurodegenerative disease.
- Short-latency reflex myoclonus is a potential characteristic of CBGD.
Observation:
- Two patients with CBGD exhibited exaggerated reflex activity in the first dorsal interosseus (FDI) muscle.
- Digital nerve stimulation led to reflex activity with a latency of 46-51 ms.
- Magnetic cortical stimulation showed enhanced facilitation, indicating spatial summation upstream from motoneurons.
Findings:
- Spatial summation occurred at the motor cortex level in CBGD patients.
- Inhibition following cortical stimulation was reduced in CBGD patients compared to normal subjects.
- This reduction suggests a loss of intrinsic cortical and corticothalamic inhibitory mechanisms.
Implications:
- Understanding the pathophysiology of CBGD.
- Potential targets for therapeutic interventions in movement disorders.
- Elucidating the role of cortical inhibitory circuits in motor control.