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Suppression of enhanced physiological tremor via stochastic noise: initial observations.

Trenado C, Amtage F, Huethe F, Schulte-Mönting J, Mendez-Balbuena I, Baker SN, Baker M, Hepp-Reymond MC, Manjarrez E, Kristeva R - PLoS ONE (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.

ABSTRACT
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.

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Motor performance (1/MAD), raw acceleration and raw rectified EMG signals and spectral power of acceleration for zero noise (ZN, black) and optimum noise (ON, red).Upper panel: Grand average of the inverse of the mean absolute deviation (1/MAD) of the finger position in (A) and the individual (1/MAD) values for each subject in (B). Note the stochastic resonance (SR) effect with better performance for ON. (C) Raw acceleration signal and raw EMG signal showing the tremor reduction. Lower panel: Grand average of the accelerometric power spectra for all patients in (D) and (E) with either ZN or ON and individual values in (F). Note the great reduction of the accelerometric spectral power as an effect of ON.
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pone-0112782-g002: Motor performance (1/MAD), raw acceleration and raw rectified EMG signals and spectral power of acceleration for zero noise (ZN, black) and optimum noise (ON, red).Upper panel: Grand average of the inverse of the mean absolute deviation (1/MAD) of the finger position in (A) and the individual (1/MAD) values for each subject in (B). Note the stochastic resonance (SR) effect with better performance for ON. (C) Raw acceleration signal and raw EMG signal showing the tremor reduction. Lower panel: Grand average of the accelerometric power spectra for all patients in (D) and (E) with either ZN or ON and individual values in (F). Note the great reduction of the accelerometric spectral power as an effect of ON.

Mentions: Fig. 2 shows the better performance when optimum noise was applied. The mean absolute deviation (MAD) values were significantly smaller in the ON than in the ZN condition as seen from the grand average of the performance (Fig. 2A) and from the individual MAD values (Fig. 2B) (p = 0.008, Wilcoxon paired test; n = 8 throughout the whole text).


Suppression of enhanced physiological tremor via stochastic noise: initial observations.

Trenado C, Amtage F, Huethe F, Schulte-Mönting J, Mendez-Balbuena I, Baker SN, Baker M, Hepp-Reymond MC, Manjarrez E, Kristeva R - PLoS ONE (2014)

Motor performance (1/MAD), raw acceleration and raw rectified EMG signals and spectral power of acceleration for zero noise (ZN, black) and optimum noise (ON, red).Upper panel: Grand average of the inverse of the mean absolute deviation (1/MAD) of the finger position in (A) and the individual (1/MAD) values for each subject in (B). Note the stochastic resonance (SR) effect with better performance for ON. (C) Raw acceleration signal and raw EMG signal showing the tremor reduction. Lower panel: Grand average of the accelerometric power spectra for all patients in (D) and (E) with either ZN or ON and individual values in (F). Note the great reduction of the accelerometric spectral power as an effect of ON.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232445&req=5

pone-0112782-g002: Motor performance (1/MAD), raw acceleration and raw rectified EMG signals and spectral power of acceleration for zero noise (ZN, black) and optimum noise (ON, red).Upper panel: Grand average of the inverse of the mean absolute deviation (1/MAD) of the finger position in (A) and the individual (1/MAD) values for each subject in (B). Note the stochastic resonance (SR) effect with better performance for ON. (C) Raw acceleration signal and raw EMG signal showing the tremor reduction. Lower panel: Grand average of the accelerometric power spectra for all patients in (D) and (E) with either ZN or ON and individual values in (F). Note the great reduction of the accelerometric spectral power as an effect of ON.
Mentions: Fig. 2 shows the better performance when optimum noise was applied. The mean absolute deviation (MAD) values were significantly smaller in the ON than in the ZN condition as seen from the grand average of the performance (Fig. 2A) and from the individual MAD values (Fig. 2B) (p = 0.008, Wilcoxon paired test; n = 8 throughout the whole text).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neurophysiology, University Freiburg, Freiburg, Germany.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus