title: Redundant-signals effects on reaction time, response force, and movement-related potentials in Parkinson's disease.
abstract: Studies using transcranial magnetic stimulation have established that patients with Parkinson's disease have increased motor cortex excitability. Relying on current evidence that the redundant-signals effect has its source in the motor system, we investigated whether, as a result of cortical hyperexcitability, Parkinson's disease patients demonstrate an enhancement of this effect. Eight patients with moderately severe Parkinson's disease and nine healthy control subjects participated in a task requiring simple manual responses to visual, auditory, and combined auditory-visual signals. During the task, motor cortex activation was recorded by means of movement-related EEG potentials, while responses were measured via isometric force recordings. The movement-related potentials and the force measures both yielded support for the view that the redundant-signals effect is partially caused in the motor system. However, the facilitatory effect of bimodal as compared to unimodal stimulation (i.e. the redundant-signals effect) was of the same size in Parkinson's disease patients and control subjects, as expressed in latency measures of the movement-related potentials and the force signals. We conclude that the redundant-signals effect is not enhanced in Parkinson's disease and that the mechanisms underlying this effect are probably not influenced by the increased motor cortex excitability found in this disease.
authors.affiliation: Department of Neurology, University Hospital, University of Nijmegen, The Netherlands.
authors.forename: F M
authors.initials: FM
authors.lastname: Plat
authors.forename: P
authors.initials: P
authors.lastname: Praamstra
authors.forename: M W
authors.initials: MW
authors.lastname: Horstink
mesh_terms: D000161:Acoustic Stimulation; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory / Q000502:physiology; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000502:physiology* / Q000503:physiopathology*; D010300:Parkinson Disease / Q000503:physiopathology*; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values