Suppression of enhanced physiological tremor via stochastic noise: initial observations.
Enhanced physiological tremor is a disabling condition that arises because of unstable interactions between central tremor generators and the biomechanics of the spinal stretch reflex. Previous work has shown that peripheral input may push the tremor-related spinal and cortical systems closer to anti-phase firing, potentially leading to a reduction in tremor through phase cancellation. The aim of the present study was to investigate whether peripherally applied mechanical stochastic noise can attenuate enhanced physiological tremor and improve motor performance. Eight subjects with enhanced physiological tremor performed a visuomotor task requiring the right index finger to compensate a static force generated by a manipulandum to which Gaussian noise (3-35 Hz) was applied. The finger position was displayed on-line on a monitor as a small white dot which the subjects had to maintain in the center of a larger green circle. Electromyogram (EMG) from the active hand muscles and finger position were recorded. Performance was measured by the mean absolute deviation of the white dot from the zero position. Tremor was identified by the acceleration in the frequency range 7-12 Hz. Two different conditions were compared: with and without superimposed noise at optimal amplitude (determined at the beginning of the experiment). The application of optimum noise reduced tremor (accelerometric amplitude and EMG activity) and improved the motor performance (reduced mean absolute deviation from zero). These data provide the first evidence of a significant reduction of enhanced physiological tremor in the human sensorimotor system due to application of external stochastic noise.
Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.
Carlos
C
Trenado
Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.
Florian
F
Amtage
Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.
Frank
F
Huethe
Institute for Medical Biometry and Medical Informatics, University Freiburg, Freiburg, Germany.
Jürgen
J
Schulte-Mönting
Facultad de Psicología, Benemérita Universidad Autónoma de Puebla, Puebla, México.
Ignacio
I
Mendez-Balbuena
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.
Stuart N
SN
Baker
Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom.
Mark
M
Baker
Institute of Neuroinformatics, University of Zürich and ETH Zürich, Zurich, Switzerland.
Marie-Claude
MC
Hepp-Reymond
Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México.
Elias
E
Manjarrez
Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.
Rumyana
R
Kristeva
D000328:Adult; D000704:Analysis of Variance; D004576:Electromyography; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D010812:Physical Stimulation / Q000379:methods*; D011597:Psychomotor Performance; D013269:Stochastic Processes; D014202:Tremor / Q000503:physiopathology* / Q000628:therapy*