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T Miao

Publications and source records attributed to T Miao.

At least 19 recordsLinked to original sources
PubMed1998

Analysis of interaction of spinal and supraspinal reflex pathways involved in physiological tremor.

A model of feedback type in which physiological tremor are produced by both muscular skeletal system and reflex action is described. Analysis of this model shows that the interaction between the spinal and the supraspinal reflex pathways is important in responsible for low and high frequency oscillations of physiological tremor. Particularly the effect of gain ratio of the two pathways is studied in order to examine the role for the two reflex pathways in controlling neuromuscular oscillations. The existence of a critical point of the gain ratio at which one oscillating frequency transitions to two ones is predicted theoretically. A shift of the critical point with variations of weight load is found and suggests a changeable correlation relation between the spinal and the supraspinal pathways due to loading conditions. Our computations for physiological tremor demonstrate the results that the high frequency component of about 25 Hz is produced by the muscle-spinal reflex loop, and the low frequency component of about 10 Hz originates from the central nervous system or from supraspinal reflex loop. Several relations derived in this study are described, and they can be compared with experimental observations. Our model sheds considerable light on the details of the possible mechanism for physiological tremor. In addition, a possibility arising from our study is that the tremulous oscillation associated with some pathological states, say Parkinson's disease, may arise from modified gains in one or more of the reflex pathways.

Humans↗
PubMed1997

An investigation of stretch reflex in physiological tremor.

This paper describes a theoretical consideration on muscle stretch reflex in physiological tremor (abbreviated as tremor). In making a model, the function of rostro-caudal homonymous motoneurone pool as well as the interaction between spinal cord mechanism and supraspinal system is investigated. The known physiology of the neuromuscular oscillations is used to evaluate the responses of a set of differential equation that represents lumped system dynamics underlying the stretch reflex process of tremor. According to the model, the stretch reflex along with the mechanics of limb is behaving as a filter. With sharp resonant peaks and without the need of any external inputs, the filter selects oscillators and sustains tremulous movement. These reflex features, especially the findings of an existence of two sharp resonant centers, are particular valuable in an explanation of the two spectral peaks observed in tremor. It is demonstrated that (1) the two peaks of tremor, which vibrate at 10 Hz and 20 Hz, largely depend on the coupling lambda between spinal and supraspinal system, i.e., lambda leads to "spontaneous symmetry breaking" producing a peak doubling; (2) the two peaks are attributable to two decoupled states found in our model. The pea with 10 Hz is attributed to the state Z+ (t) describing an average state of spinal+supraspinal system, while the one with 20 Hz denotes the state Z-(t) which presents a relative movement of spinal and supraspinal system. With regarding to the nature of tremor under various conditions such as loading, fatigue, and pseudo-gravity, this paper discusses the possible connections of lambda to these experimental environments. Also, this paper argues that representation of stretch reflex by the decoupled states is more essential than other traditional representations used in approaching to tremor phenomena.

Animals↗
PubMed1995

Monitoring accumulative fatigue of finger by autoregressive modeling of physiological tremor.

In this study, block data structured autoregressive (AR) method is used to evaluate fatigue, based on physiological tremor during and after loading a weight mass on the index finger. The temporal changes in the prediction coefficients and the reflection coefficients are determined. AR spectral estimation with the ninth-order is obtained and presented in graphical form. The results indicate that the first prediction coefficient a1 can be used to characterize the state of fatigue of finger muscle and the other prediction coefficients do not show any tendency for the finger load. The coefficient a1 can be applied to monitor the accumulative fatigue induced by the weight loading for a duration of time.

Adult↗
PubMed1995

Physiological tremor under pseudo-fraction gravity.

The effect of pseudo-fraction gravity on physiological tremor of the human finger (finger tremor) has been examined experimentally by immersing an index finger into water at different immersion levels. The pseudo-fraction gravity, gamma G, was established by water buoyancy at immersion level omega, G being gravitation acceleration and gamma between zero and unit. The nature of variations of finger tremor under the influence of gamma G is estimated based on FFT spectral analysis. It is illustrated that with a decrease in gamma, or equivalently an increase in omega, two dominant peaks remaining approximately constant in frequencies around 10Hz and 20Hz are found, while peak amplitude is decreased rapidly for higher peak and slowly for lower one. Theoretically the effect of pseudo-fraction gravity is analyzed in terms of a specific model for finger tremor. The experimental results presented in this paper are predicted rather well by two resonant modes which occurred in our model system. It is possible to conclude that the model, which is characterized by a pair of antagonistic muscles and two reflex pathways, provides an adequate quantitative description of finger tremor.

Adult↗
PubMed1995

Effects of weight load on physiological tremor: the AR representation.

The propriety of the autoregressive (AR) method as a means of processing the signals of physiological tremor of human finger (finger tremor) was investigated. Application of the Akaike's criterion demonstrated that the 15-th order AR model was required to describe the recordings of finger tremor. According to Burg's algorithm, both AR spectrum and AR parameters were estimated to study the effects of various weight loads on finger tremor. It was found that, (1) the amplitude of AR spectrum was apparently enhanced by adding the load; (2) the first prediction coefficient (a1) and the first reflection coefficient (rho 1) significantly declined by increasing the weight loads. The results were compared with the calculations from FFT (Fast Fourier Transform) and autocorrelation function. Simple physical interpretation of the AR parameters (i.e. a1 and rho 1) was discussed in relation with system's resonant modes.

Algorithms↗