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Neurophysiological correlates of bradykinesia in Parkinson's disease
- Publication Year :
- 2018
-
Abstract
- Many neurophysiological abnormalities have been described in the primary motor cortex of patients with Parkinson's disease. However, it is unclear whether there is any relationship between them and bradykinesia, one of the cardinal motor features of the condition. In the present study we aimed to investigate whether objective measures of bradykinesia in Parkinson's disease have any relationship with neurophysiological measures in primary motor cortex as assessed by means of transcranial magnetic stimulation techniques. Twenty-two patients with Parkinson's disease and 18 healthy subjects were enrolled. Objective measurements of repetitive finger tapping (amplitude, speed and decrement) were obtained using a motion analysis system. The excitability of primary motor cortex was assessed by recording the input/output curve of the motor-evoked potentials and using a conditioning-test paradigm for the assessment of short-interval intracortical inhibition and facilitation. Plasticity-like mechanisms in primary motor cortex were indexed according to the amplitude changes in motor-evoked potentials after the paired associative stimulation protocol. Patients were assessed in two sessions, i.e. OFF and ON medication. A canonical correlation analysis was used to test for relationships between the kinematic and neurophysiological variables. Patients with Parkinson's disease tapped more slowly and with smaller amplitude than normal, and displayed decrement as tapping progressed. They also had steeper input/output curves, reduced short-interval intracortical inhibition and a reduced response to the paired associative stimulation protocol. Within the patient group, bradykinesia features correlated with the slope of the input/output curve and the after-effects of the paired associative stimulation protocol. Although dopaminergic therapy improved movement kinematics as well as neurophysiological measures, there was no relationship between them. In conclusion, neurophysiological changes in primary motor cortex relate to bradykinesia in patients with Parkinson's disease, although other mechanisms sensitive to dopamine levels must also play a role.
- Subjects :
- 0301 basic medicine
Male
Parkinson's disease
medicine.medical_treatment
Movement
Neurophysiology
Hypokinesia
Levodopa
03 medical and health sciences
0302 clinical medicine
Dopamine
Medicine
Aged
Biomechanical Phenomena
Evoked Potentials, Motor
Female
Humans
Middle Aged
Motor Cortex
Neuronal Plasticity
Parkinson Disease
Transcranial Magnetic Stimulation
Evoked Potentials
Repetitive finger tapping
business.industry
Dopaminergic
medicine.disease
Transcranial magnetic stimulation
030104 developmental biology
Motor
Facilitation
Neurology (clinical)
Primary motor cortex
business
Neuroscience
030217 neurology & neurosurgery
medicine.drug
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....7c477cb5197e2d5e528ade31f1b75bd1