Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study concerned the hypothesis presented by Lindsley in 1961 that human sensorimotor performance should vary with the phase of the alpha cycle. Although there have been a number of studies which have supported this hypothesis, there has been no work from a modality other than the visual modality. Since eye tremor is correlated in phase and frequency with the alpha rhythm, these visual results might be explained by the peripheral eye tremor and not necessarily by the central alpha rhythm. The present study measured human auditory signal-detection performance at four different phases of the temporally (T5-linked mastoids) measured alpha rhythm. These four different phases were defined on an a priori basis by a computer algorithm. Detection performance was significantly better at the negative peak of this alpha cycle than at the positive peak, but there was no significant difference between the positively and negatively going zero cross performances. These results are consistent with the Lindsley hypothesis.
Percept Mot Skills 1989 Oct
PMID:Some evidence in support of a relationship between human auditory signal-detection performance and the phase of the alpha cycle. 281 90

A single case of one-to-one correspondence between eyelid flutter and EEG alpha rhythm is reported. It arose during a battery of experiments into possible personality correlates of eyelid conditioning, EEG evoked potential and skin potential habituation, involving over 400 subjects. The reported phenomenon lasted for one burst of 24 sec. and another of 6 sec. during 40 min. of recording on one subject. The observation is considered in the light of reported cases of links between EEG alpha and epileptic seizure and also between EEG alpha, Parkinsonism, and finger tremor. A time-keeping role for EEG alpha in the brain is postulated.
Percept Mot Skills 1987 Jun
PMID:EEG alpha rhythm and eyelid flutter. 360 93

Healthy individuals (n = 6) and a patient with "pure" primary writing tremor executed pointing and drawing movements while adopting different hand postures. The control subjects and the patient exhibited similar kinematics for most conditions. The patient displayed a severe right hand 4- to 6-Hz tremor and prolonged movements only when drawing with his normal hand posture. His tremor was manifested after a ready cue, in anticipation of a go command. The premovement tremor was abolished when the authors simply eliminated the ready cue and instructed the patient to relax and not think about drawing until he heard the go cue. Thus, the patient's writing tremor depended not only upon the writing or drawing act but also upon the hand position adopted and the intent to write, even in the absence of movement. The present results suggest that (a) similar high-level control mechanisms exist for pointing and drawing in healthy subjects and (b) the patient's deficits are compatible with a higher motor defect in central nervous system structures involved in the control of pointing and drawing movements.
J Mot Behav 1999 Jun
PMID:Effect of Hand Posture on the Temporal and Kinematic Properties of Pointing and Drawing Movements Executed by Healthy Subjects and by a Patient With Primary Writing Tremor. 1117 30

Experiments were performed to investigate the oscillations arising in a human motor system with delayed visual feedback. Eight subjects were instructed to maintain a constant finger position relative to a stationary baseline. The finger displacement was measured using a microdisplacement transducer connected to the index finger, and was displayed on an oscilloscope. Time delays between 40 and 1,500 ms were inserted in the visual feedback loop for 100 s. Results show that, as the time delays increase, irregular rhythms appear with short intermittent periods of regular oscillations. These regular low-frequency oscillations have an amplitude that increases with the time delays and a period that is consistently about 2 to 4 times the time delay. Fast Fourier Transforms (FFT) show a peak between 8 and 12 Hz, corresponding to physiological tremor in half the subjects. No systematic variations in the FFT for the 2 to 15 Hz range were observed as time delay increased. In the 0 to 2 Hz range, the FFT show a consistent increase in power with the time delay. These results indicate that, under the conditions of this experiment, tremor is not affected by time delays in the visuomotor system, and time delays in the visuomotor feedback loop give rise to complex oscillatory behaviors.
J Mot Behav 1989 Sep
PMID:Complex oscillations in a human motor system. 1513 65

Isometric impulse frequencies associated with active tremor and force regulation were examined in 10 patients with idiopathic Parkinson's disease (PD) and in 10 older adults (OAs) who performed an isometric tracing task. The authors decoupled and analyzed the data to determine whether PD-related tremor in the thumb and in the index finger during isometric force control are related and whether PD impairs the performance of volitional force control beyond the errors contributed by tremor. After decoupling, there were clear and robust differences in PD patients' control of isometric force that could not be attributed to action-tremor error. Those errors, which occurred in the absence of movement, suggest impairment in coordinated recruitment and derecruitment of motor units during a fine-motor task.
J Mot Behav 2005 May
PMID:Quantification of manual force control and tremor. 1588 17

The authors investigated the coordination of periodic right-hand tapping with single stimulus-evoked discrete lefthand taps to check for task interactions and a possible relationship between phase resetting (see tapping literature; e.g., J. Yamanishi, M. Kawato, & R. Suzuki, 1979) and phase entrainment (see tremor literature; e.g., R. J. Elble, C. Higgins, & L. Hughes, 1994). The experimental paradigm employs a dual-task condition as used by K. Yoshino, K. Takagi, T. Nomura, S. Sato, and M. Tonoike (2002), and it includes normal tapping and isometric tapping with the authors recording finger positions and ground contact forces. Four different types of coordination schemes were observed in tapping behavior: marginal tapping interaction (MTI), periodic tap retardation (PTR), periodic tap hastening (PTH), and discrete tap entrainment (DTE); MTI and PTR correspond to the phase-resetting effect for the coordination of periodic tapping with single discrete taps. The novel aspect of the study described in this article includes the impact of the periodic tapping on the discrete tap timing and the hastening of the periodic tapping due to the discrete tap behaviors resulting in a synchronized execution of the two concurrent tapping tasks. All participants showed a dominant tapping behavior, but they all used the other nondominant forms of the four reported coordination schemes in some trials too, which reflects possible constraints of the sensorimotor system in handling two competing tasks.
J Mot Behav 2008 Sep
PMID:Coordination of a discrete response with periodic finger tapping: additional experimental aspects for a subtle mechanism. 1878 17

The authors sought to determine whether repeated practice of a skilled motor task reduced the tremor arising from pulsatile control that occurs during and after training. Participants flexed and extended their index finger at the metacarpophalangeal joint to track a screen cursor during skill training, in 6 training runs, each of 3-min duration. Nonskill training comprised voluntary flexion and extension movements. The authors measured performance by the average tracking error in a standard 10-s target pattern embedded in the training runs. Cross-correlation of the motor performance and the target pattern revealed that the improved ability to match the shape of the target pattern accounted for 63% of the improved motor performance and that the decreased time to respond to changes in the target line accounted for 10% of the improvement. Skill, but not nonskill training, reduced tremor after 3 min of training during the training movements and during movements 10 and 25 min afterwards. The authors observed no changes in resting tremor after either training protocol. Although training reduced the tremor, this reduction in itself did not significantly improve tracking performance. The authors conclude that visuomotor skill training produces a general reduction in finger tremor (pulsatile control) during voluntary movements that extends beyond the period of training.
J Mot Behav 2009 Jan
PMID:Motor training decreases finger tremor and movement response time in a visuomotor tracking task. 1907 71

The aging process is associated with a general decline in biological function. One characteristic that researchers believe represents this diminished functioning of the aging neuromuscular system is increased physiological tremor. The present study is constructed to assess what age-related differences exist in the dynamics of tremor and forearm muscle activity under postural conditions in which the number of arm segments involved in the task was altered. The authors predicted that any alteration in the tremor or electromyographic (EMG) output of these two groups would provide a clearer understanding of the differential effects of aging or task dynamics on physiological function. Results reveal no age-related differences in finger tremor or forearm extensor muscle EMG activity under conditions in which participants were only required to extend their index finger against gravity. However, when participants had to hold their entire upper limb steady against gravity, the authors observed significant increases in forearm EMG activity, finger-tremor amplitude, power in the 8-12-Hz range, and signal regularity between the 2 age groups. The selective changes in signal regularity, EMG activity, and 8-12-Hz tremor amplitude under more challenging postural demands support the view that the age-related changes in neuromuscular dynamics are not fully elucidated when single task demands are utilized.
J Mot Behav 2009 May
PMID:Age-related changes in the adaptability of neuromuscular output. 1936 59

In this study, the interaction between increased gain in the visual feedback loop and motor control of the periphery was investigated. Participants (N = 15) were asked to maintain a constant finger position while they used magnified visual feedback. The measure of the accuracy of each trial was the standard deviation (trial error) of the finger position. Trials performed under magnification had lower trial errors than trials without magnification. The change in trial error between trials with and without magnification proved greater than the difference between trials at any 2 magnifications. In contrast, the differences between individual subjects were often greater than the differences between performances at individual magnifications. At higher magnifications, performance seemed to be limited by the tremor; the ratio of trial error to tremor intensity was constant. When applied to microsurgery, the present results accord with those found in earlier research, including investigations that have found that the level of magnification used in microsurgery is not the most significant factor in achieving good results and that tremor is the limiting factor in microsurgical tasks.
J Mot Behav 1998 Jun
PMID:Interaction of tremor and magnification in a motor performance task with visual feedback. 2003 31

The purpose was to test whether specific characteristics of handwriting can distinguish patients diagnosed with major depression from healthy controls and patients with bipolar disorder. Handwriting samples from 30 patients with major depressive disorder and 30 patients in the bipolar depressive phase were compared to samples from 30 patients in the bipolar manic phase and 60 healthy controls. Forensic document experts examined all 150 written samples of the same text and empirically measured graphical aspects potentially related to depression, such as direction of the baseline, pen pressure, tremor, forms of the letters 'm', 'n', 'a', and 'o', sizes of the letters and writing zones, the initial and final shapes of letters, slant, and impulse. Three handwriting parameters of 32 examined differed significantly between controls and patients with depression (major depression or depressed bipolar patients). However, there were no statistically significant differences in these parameters between depressed patients and bipolar patients in the manic phase, indicating that these handwriting characteristics cannot distinguish depressed patients from manic patients. The main hypothesis, that psychomotor slowing is visible in handwriting, was not confirmed.
Percept Mot Skills 2013 Aug
PMID:Little evidence for the graphical markers of depression. 2442 58


1 2 Next >>