Mechanical and neural feedback factors in postural hand tremor of normal subjects.

1980 ◽  
Vol 44 (1) ◽  
pp. 40-59 ◽  
Author(s):  
R N Stiles
Keyword(s):  
Normal Subjects ◽  
Hand Tremor ◽  
Neural Feedback

Acceleration time series resulting from repetitive extension-flexion of the hand

1975 ◽  
Vol 38 (1) ◽  
pp. 101-107 ◽  
Author(s):  
R. N. Stiles
Keyword(s):  
Frequency Band ◽  
Normal Subjects ◽  
Peak Frequency ◽  
Hand Tremor ◽  
Low Frequencies ◽  
Frequency Bands ◽  
Normal Hand ◽  
The Subject ◽  
The Time Domain ◽  
Oscillation Frequencies

Power, or variance, spectra of acceleration records obtained from normal subjects during extension-flexion oscillations of a hand at frequencies between 0.5–5.0 Hz generally contained two or three frequency bands. Partial separation of these oscillations in the time domain was obtained using the method of digital filtering (smoothing). In general, the peak frequency of the lowest frequency band occurred at, or nearly at, the frequency that the subject attempted to maintain during a 16-s digitization period. Consideration of absolute frequencies and the effect of mass on frequency indicated that one of the higher frequency bands was the result of normal hand tremor. For low frequencies of voluntary oscillation (0.5–1.25 Hz), a second, higher frequency band occurred with a peak frequency (3.0–4.25 Hz) within the range (3–6 Hz) usually reported for abnormal hand tremor. For voluntary oscillation frequencies above about 1.5 Hz, this second, higher frequency oscillation generally occurred at twice the frequency of the voluntary oscillation.

Involuntary ankle oscillations from normal subjects

1977 ◽  
Vol 233 (1) ◽  
pp. R8-R14
Author(s):  
R. N. Stiles ◽  
R. R. Rietz
Keyword(s):  
Spectral Analysis ◽  
Root Mean Square ◽  
Power Function ◽  
Normal Subjects ◽  
Displacement Amplitude ◽  
Mean Square ◽  
Hand Tremor ◽  
Negative Relation ◽  
Tremor Frequency

Spectral analysis of ankle tremor records obtained from normal seated subjects during continuous elevation of the heel for 10-45 min revealed that the root-mean-square (rms) displacement amplitude of the tremor increased from minimum values of about 4 micronm to values as large as 4,000 micronm. Associated with this increase in the displacement amplitude was a systematic decrease in the tremor frequency from values of 7-8 Hz to values of 5-6 Hz. Spectral analysis of demodulated soleus EMG records indicated that the rms value of this EMG (calculated at the tremor frequency) and the rms displacement of the tremor are related by a power function, with the rms value of the EMG increasing over a range of about 4-40 micronV as the tremor displacement increased from about 4 to 4,000 micronm. The negative relation between frequency and rms displacement amplitude values for postural ankle tremor was similar to that found previously for postural hand tremor.

Frequency and displacement amplitude relations for normal hand tremor

1976 ◽  
Vol 40 (1) ◽  
pp. 44-54 ◽  
Author(s):  
R. N. Stiles
Keyword(s):  
Spectral Analysis ◽  
Small Amplitude ◽  
Continuous Extension ◽  
Normal Subjects ◽  
Displacement Amplitude ◽  
Modulation Amplitude ◽  
Mean Square ◽  
Hand Tremor ◽  
Normal Hand ◽  
Tremor Frequency

Spectral analysis of hand tremor records obtained from normal subjects during continuous extension of the hand for 15–45 min revealed that the root-mean-square (rms) displacement amplitude of the tremor increased from control levels of about 30 mum to levels on the order of 100–1,000 times control. Associated with this increase in the displacement was a systematic decrease in the hand tremor frequency from control values of 8–9 Hz to values of 4–6 Hz. Spectral analysis of demodulated extensor EMG records indicated a consistent relation between EMG modulation amplitude at the tremor frequency and the tremor displacement amplitude for tremor records with rms displacement above about 100 mum. No consistent relation was found between these two variables for tremor records with displacements below 100 mum. Consideration of both mechanical and neural reflex effects indicated that a viscoelastic-mass mechanism primarily determined the small-amplitude (less than 100 mum) tremors, while the large displacement tremors may have involved both mechanical and neural feed back factors.

A mechanical-reflex oscillator hypothesis for parkinsonian hand tremor

1976 ◽  
Vol 40 (6) ◽  
pp. 990-998 ◽  
Author(s):  
R. N. Stiles ◽  
R. S. Pozos
Keyword(s):  
Spectral Analysis ◽  
Steady State ◽  
Root Mean Square ◽  
Fold Increase ◽  
Normal Subjects ◽  
Single Frequency ◽  
Mean Square ◽  
Hand Tremor ◽  
S Period ◽  
Rms Amplitude

Spectral analysis was performed on postural hand tremor records obtained from 22 parkinsonian subjects. Of these 22 subjects, 18 had postural hand tremor that occurred primarily at a single frequency during any one 16-s period. In general, this tremor occurred at different steady-state frequencies (each calculated over 16 s) between about 4 Hz and 8–9 Hz. This frequency decreased approximately 1 Hz for each 10-fold increase in displacement amplitude (root-mean-square, rms, amplitude determined at 16 cm from the wrist), decreasing from 8–9 Hz at about 30 mum to 3.75–4.0 Hz at about 30,000 mum. The major finding was that the frequency of parkinsonian hand tremor was nearly the same as that for hand tremor from normal subjects when these frequenceis were compared at similar rms displacement levels. This comparison, plus a comparison between other aspects of these two kinds of tremor, indicate that the mechanism for parkinsonian hand tremor is similar to that for large-displacement (greater than 100 mum) hand tremor of normal subjects, i.e., a mechanical-reflex oscillator mechanism.

Auditory Selective Attention in Cerebral-Palsied Individuals

1985 ◽  
Vol 16 (4) ◽  
pp. 260-266 ◽  
Author(s):  
Lee Ann Laraway
Keyword(s):  
Selective Attention ◽  
White Noise ◽  
Normal Subjects ◽  
Auditory Selective Attention ◽  
Normal Individuals ◽  
Significant Difference

The purpose of this study was to determine whether there is a statistically significant difference between the auditory selective attention abilities of normal and cerebral-palsied individuals. Twenty-three cerebral-palsied and 23 normal subjects between the ages of 5 and 21 were asked to repeat a series of 30 items consisting of from 2 to 4 digits in the presence of intermittent white noise. Results of the study indicate that cerebral-palsied individuals perform significantly poorer than normal individuals when the stimulus is accompanied by noise. Noise was not a significant factor in the performance of the normal subjects regardless of age.

The Effect of Stapedectomy on the Loudness of One’s Own Voice

1965 ◽  
Vol 8 (3) ◽  
pp. 223-234 ◽  
Author(s):  
William Melnick
Keyword(s):  
Middle Ear ◽  
Normal Subjects ◽  
Sound Energy ◽  
Loudness Function ◽  
Before And After ◽  
Increased Sensitivity

Five subjects with normal middle ear mechanisms, and otosclerotic patients, before and after stapedectomy, matched the loudness of their voices to the loudness of a 125-cps-sawtooth noise. The results showed loudness matching functions with gradual slopes, less than 1.00, for the normal subjects and the patients prior to stapedectomy. Post-surgically, the loudness function for the patients increased in steepness to considerably more than 1.00. These results are explained, most logically, in terms of increased sensitivity of the altered middle ear to sound energy generated by the listener’s own voice.

Delayed Auditory Feedback with Different Delay Times at Each Ear

1964 ◽  
Vol 7 (4) ◽  
pp. 369-371
Author(s):  
Samuel Fillenbaum
Keyword(s):  
Delay Interval ◽  
Auditory Feedback ◽  
Normal Subjects ◽  
Delayed Auditory Feedback ◽  
Delay Times

Binaurally asynchronous delayed auditory feedback (DAF) was compared with synchronous DAF in 80 normal subjects. Asynchronous DAF (0.10 sec difference) did not yield results different from those obtained under synchronous DAF with a 0.20 sec delay interval, an interval characteristically resulting in maximum disruptions in speech.

Object Transformations in the Play of Language-Impaired Children

1988 ◽  
Vol 53 (4) ◽  
pp. 459-466 ◽  
Author(s):  
Brenda Y. Terrell ◽  
Richard G. Schwartz
Keyword(s):  
Normal Subjects ◽  
Play Behavior ◽  
Chronological Age ◽  
Standard Group ◽  
Language Impaired ◽  
Normal Language ◽  
Mean Length Of Utterance ◽  
Impaired Children

The play behavior of 10 language-impaired children was observed. Their performances in play were compared to those of 10 normal-language children matched for chronological age as well as to those of 10 normal-language children matched for mean length of utterance. The children were observed as they played spontaneously with a standard group of toys and as they played with objects that required object transformations for successful play. The chronological age-matched normal subjects showed a trend toward performance of more object transformations in play than either the language-impaired or younger normal-language children. Additionally, although object transformations were observed in both segments, all children performed more object transformations with objects than with toys.

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