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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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EMG spectral power for zero noise (ZN, black) and optimum noise (ON, red).(A–C): Power spectra for FDI muscle activity for subject 8 and for FDS muscle activity for subjects 3 and 4 with ZN and ON, highlighting the tremor frequency. (D) For all eight subjects, effect of ON on the EMG power spectra (i.e. % of EMG tremor reduction) of FDI, FDS, EDC muscles (at the individual tremor frequency).
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pone-0112782-g003: EMG spectral power for zero noise (ZN, black) and optimum noise (ON, red).(A–C): Power spectra for FDI muscle activity for subject 8 and for FDS muscle activity for subjects 3 and 4 with ZN and ON, highlighting the tremor frequency. (D) For all eight subjects, effect of ON on the EMG power spectra (i.e. % of EMG tremor reduction) of FDI, FDS, EDC muscles (at the individual tremor frequency).

Mentions: Figure 3 A–C depicts example frequency power spectra from the FDI muscles for subject 8 and from the FDS muscle activity for subjects 3 and 4. The reduction in the tremor frequency band is clearly visible. Figure 3D illustrates for individual data of the EMG spectral power reduction for all muscles at the tremor frequency, with reductions of 44±29% for the FDI, 44±24% for the FDS and 20±27% for the EDC (mean ± SD).


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)

EMG spectral power for zero noise (ZN, black) and optimum noise (ON, red).(A–C): Power spectra for FDI muscle activity for subject 8 and for FDS muscle activity for subjects 3 and 4 with ZN and ON, highlighting the tremor frequency. (D) For all eight subjects, effect of ON on the EMG power spectra (i.e. % of EMG tremor reduction) of FDI, FDS, EDC muscles (at the individual tremor frequency).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0112782-g003: EMG spectral power for zero noise (ZN, black) and optimum noise (ON, red).(A–C): Power spectra for FDI muscle activity for subject 8 and for FDS muscle activity for subjects 3 and 4 with ZN and ON, highlighting the tremor frequency. (D) For all eight subjects, effect of ON on the EMG power spectra (i.e. % of EMG tremor reduction) of FDI, FDS, EDC muscles (at the individual tremor frequency).
Mentions: Figure 3 A–C depicts example frequency power spectra from the FDI muscles for subject 8 and from the FDS muscle activity for subjects 3 and 4. The reduction in the tremor frequency band is clearly visible. Figure 3D illustrates for individual data of the EMG spectral power reduction for all muscles at the tremor frequency, with reductions of 44±29% for the FDI, 44±24% for the FDS and 20±27% for the EDC (mean ± SD).

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