Different gripping intervals in reproducibility of force-decreasing curve and muscle oxygenation kinetics during sustained maximal gripping

The purpose was to examine the properties and reproducibility of the force-decreasing curve and muscle-oxygenation kinetics measured by near infrared spectroscopy in sustained isometric grip and rhythmic repeated grip measurements using various contraction intervals (2 to 5 sec.). 10 healthy young adults performed both grip tests for 6 min., during which muscle-oxygenation kinetics were measured. The intraclass correlation coefficients of the time to reach the minimum value for oxygenated hemoglobin and myoglobin tended to become lower with longer relaxation time, especially over a 3-sec. interval. Although blood-flow obstruction closely influences the initial decreasing grip force during both grip tests with a 2-sec. interval, the decreasing grip force during rhythmic repeated gripping with over a 3-sec. interval is low. Hence, the physiological mechanism related to rhythmic repeated grip with over a 3-sec. interval may differ from that related to sustained isometric grip and rhythmic repeated grip with a 2-sec. interval.     

Power spectrum characteristics of sway position and velocity of the center of pressure during static upright posture for healthy people

This study assessed sex and individual differences in sway-position and velocity power spectra and reliability of power frequency with 30 health young people. The body sway for 1 min. was measured twice over a 1-min. rest. There were no significant sex differences in the spectra. Frequency bands with a large coefficient of variance over 10.0 appeared up to 0.6 Hz. 75% relative accumulated power frequency appeared at 1.10-1.23 Hz in the position and at 2.00-3.05 Hz in the velocity spectra. Most power was in the low frequency band (A and B frequency intervals) of the international standard. Relative accumulated power frequency of position and velocity power spectra was reasonably reliable. It may be necessary to establish a new evaluation frequency interval by direction of sway-position and velocity using relative accumulated power frequency for healthy people.     

Influence of instruction on evaluation of repeated muscular endurance

This study was done to examine the influence of instructions on the evaluation of rhythmic repeated muscular endurance, that is, the ability to continue muscle-power exertion at a regular interval. 15 healthy young male adults performed maximal repeated rhythmic grips for 6 min. under the following three instruction conditions: (1) "Squeeze freely during the 2-sec. interval," (2) "Squeeze quickly and then relax," and (3) "Squeeze quickly and then hold the exertion for 1 sec." Time to peak force was slower in Condition 1 than in Condition 2. A decline in exertion of force was found for all conditions after 1 min. The decline in rate of the peak values in Conditions 1 and 3 was about 10 to 15% larger than that of Condition 2. In conclusion, proper instructions are necessary, even for a short 2-sec. interval, when evaluating muscular endurance with repeated rhythmic grips. Condition 2 instruction may be most effective.     

Persistent visual aura following catheter ablation in a patient with WPW syndrome

We report a patient who has had persistent visual disturbances since she underwent catheter ablation to treat her Wolff-Parkinson-White (WPW) syndrome. We examined her visual symptoms carefully and quantitatively by means of our newly developed method combining image-processing and psychophysics. We first simulated the patient's visual symptoms using image-processing techniques. Since the simulation indicated that she would be very sensitive to the edges of the visual stimuli, we evaluated her sensitivity to the edges using psychophysics. The results indicated that she was hypersensitive to the clear-cut edges of the visual stimuli. Her visual symptoms were very similar to those of visual aura of migraine, rather than those of photosensitive epilepsy. Magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT), electroenchepalogram (EEG), and visual-evoked potentials (VEP) in the patient were normal. No abnormalities in her fundus, visual field, or electroretinogram were found, either. Transesophageal echocardiography with bubble study indicated that she had a preexisting right-to-left shunt. We hypothesize that visual aura of migraine was triggered and made persistent by the catheter ablation in this patient. Although the relationship between migraine, catheter ablation, and right-to-left shunts is unknown, previous studies on the transcatheter closure of patent foramen ovale suggest a possible link between them. Catheter ablation in patients with migraine and preexisting shunts may lead to exacerbations in migraine symptoms.     

Static one-legged balance in soccer players during use of a lifted leg

The goal was to describe static one-legged balance during use of a lifted leg and to compare balance between the dominant and nondominant legs of soccer players. Participants were 17 male soccer players and 17 untrained male students (control). Balance ability was evaluated with four sway measures: sway velocity, anterior-posterior sway, medial-lateral sway, and high-frequency sway. Soccer players had smaller magnitude mean anterior-posterior and medial-lateral sway than untrained students. Although mean sway velocity and anterior-posterior sway were higher with the dominant leg than in the nondominant leg of the control group, there was no significant difference on any sway factor between the two legs of the soccer group. In conclusion, the soccer players were observed to have superior static one-legged balance during use of a lifted leg, and there is no difference in balance for the two legs in the soccer group.     

Multi-aspect data analysis for investigating human computation mechanism

In the paper, we present a multi-aspect data analysis approach for investigating human computation mechanism. Multi-aspect analysis in multiple human brain data sources is an important methodology in Brain Informatics, which emphasizes on a systematic way for investigating human information processing mechanisms, including measuring, collecting, modeling, transforming, managing, and mining multiple human brain data obtained from various cognitive experiments by using powerful equipments, such as fMRI and EEG. After giving an outline of Brain Informatics methodology, we describe how to design cognitive experiments of mental arithmetic task with multiple difficulty levels for obtaining multiple EEG and fMRI data sources, and how to analyze such data for investigating the spatiotemporal characteristics and flow of human computation processing. Such an investigation can be regarded as a case study using Brain Informatics methodology. Experimental results show the usefulness of our approach.     

Individual differences in the biomechanical effect of loudness and tempo on upper-limb movements during repetitive piano keystrokes

The present study addressed the effect of loudness and tempo on kinematics and muscular activities of the upper extremity during repetitive piano keystrokes. Eighteen pianists with professional music education struck two keys simultaneously and repetitively with a combination of four loudness levels and four tempi. The results demonstrated a significant interaction effect of loudness and tempo on peak angular velocity for the shoulder, elbow, wrist and finger joints, mean muscular activity for the corresponding flexors and extensors, and their co-activation level. The interaction effect indicated greater increases with tempo when eliciting louder tones for all joints and muscles except for the elbow velocity showing a greater decrease with tempo. Multiple-regression analysis and K-means clustering further revealed that 18 pianists were categorized into three clusters with different interaction effects on joint kinematics. These clusters were characterized by either an elbow-velocity decrease and a finger-velocity increase, a finger-velocity decrease with increases in shoulder and wrist velocities, or a large elbow-velocity decrease with a shoulder-velocity increase when increasing both loudness and tempo. Furthermore, the muscular load considerably differed across the clusters. These findings provide information to determine muscles with the greatest potential risk of playing-related disorders based on movement characteristics of individual pianists.     

Concurrent validity of tests to measure the coordinated exertion of force by computerized target pursuit

The purpose of this study was to examine concurrent validity of a new test for coordinated exertion of force. Coordinated exertion of force was measured using computerized target pursuit from the following viewpoints: the relations between the new test, a pursuit-rotor test, and a pegboard test. College students (24 men and 24 women) were required to change their grip exertion to match changing demand values (displayed in either a bar chart or a wave form) appearing on the display of a personal computer. The sum of the differences between the demanded values and grip-exertion values for 25 sec. was a parameter to evaluate the new test. The reliabilities of the new test, the pursuit-rotor, and the pegboard test were acceptable (ICC = .70 to .99). Scores on the new test showed low correlations with the pursuit-rotor and the pegboard test. The relation between the two different displays in the new test was significant but low (r = .49, p < .05). It was inferred that the new test measures a somewhat different ability than that measured by the pursuit-rotor and pegboard test and that the abilities tested by the types of displayed demand values are somewhat different.     

Controlled exertion of force by developmentally delayed young men and women

Present purposes were to examine the characteristics of controlled force exertion in 28 developmentally delayed young people (14 men, 14 women), and sex differences compared to 28 normal young students (14 men, 14 women). The subjects matched their submaximal grip strength to changing demand values displayed in a bar chart on the display of a personal computer. The total sum of the differences between the demand value and grip exertion value for 25 sec. was used as an evaluation parameter for the test. The controlled force exertion was significantly poorer for he developmentally delayed group than for controls, and there were large individual differences. The developmentally delayed men scored poorer than women in coordination. Like the controls, the means between trials did not decrease significantly. For these developmentally delayed subjects, performance did not improve after only a few trials. The controlled force-exertion test is useful as a voluntary movement-function test for developmentally delayed subjects.