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Biomedical subjects

K Tanii

Publications and source records attributed to K Tanii.

16 recordsLinked to original sources
PubMed1997

Influence of long-latency reflex modulation on the performance of quick adjustment movements.

The effect of long-latency reflex modulation on the performance of a quick adjustment movement following a muscle stretch was studied in 26 healthy male subjects. When the subjects felt a sudden angle displacement in the direction of a wrist extension they were required to make an adjustment movement by moving a handlebar, held in the hand, to align with a target position as quickly and as accurately as possible. The index of performance (adjustment time) was the time taken to move the handle to the target position from stretch onset. A DC torque motor was used to evoke electromyographic (EMG) reflex responses on a wrist flexor. Averaging of the rectified EMG, recorded from surface electrodes placed over the flexor, showed short- and long-latency reflexes (M1 and M2 components). For all subjects, the amplitudes of the reflex components decreased during the adjustment movement because the target position for this study was fixed to the extension side of the wrist joint. The decrease in the M2 component, which is considered to be a transcortical reflex, was significantly larger than the decrease in the M1 component, which is spinal reflex. The main finding was of a positive correlation between the length of adjustment time and the degree of reduction of M1 and M2 with the adjustment movement (r = 0.602 for M1, P < 0.01; r = 0.850 for M2, P < 0.001). Moreover, there were correlations between the consistency of the voluntary response onset and the degree of M2 decrease (r = 0.577, P < 0.01), and between the consistency of the voluntary response onset and the length of the adjustment time (r = 0.603, P < 0.01). Therefore, we have concluded that the subjects who were able to perform adjustment movements within a short time could modulate the long-latency reflex of the muscle involved in such movements in order to make the function of their voluntary muscle activity more effective, and thus were able to respond appropriately.

Adult↗
PubMed1997

Relationship between the degree of inhibited stretch reflex activities of the wrist flexor and reaction time during quick extension movements.

It has been reported that stretch reflex responses, including the long latency component, are modulated by motor preparation for the direction and type of movement. In the present study, human subjects were required to make a reaction movement in the direction of the wrist extension following a muscle stretch to the wrist flexor, and we investigated the relationship between the modulation of reflex activities of the wrist flexor and the length of reaction time (premotor time) of the wrist extensor. Twenty-five healthy males, ranging in age from 20 to 28, participated in the experiments. A DC torque motor was used to evoke the reflex EMG responses on the flexor. Averaging the rectified EMG, recorded with the surface electrodes over the flexor, showed short and long latency reflexes (M1 and M2 components) in response to the muscle stretch. For all subjects, the amplitudes of the reflex components during the extension reaction movement decreased, compared to those amplitudes in the non-reaction tasks. The decrease in the M2 component, which is considered a transcortical reflex, was significantly larger than the decrease in the M1 component, which is a spinal reflex. Moreover, there were correlations between reaction time to muscle stretch and the degree of decrease in reflex activities with the extension reaction (r = 0.652 for M1, r = 0.813 for M2, P < 0.01). It became clear that the subjects with shorter reaction times inhibited their reflex activities of the flexor, particularly the M2 component which prevents the extension movement, to a greater degree than the subjects with longer reaction times. Therefore, our results suggest that the degree of M2 modulation directly reflects the individual motor control required to perform quick movements.

Adult↗
PubMed1996

Comparative study of the premovement muscle silent period and the premovement cortical potential in different modes of voluntary contraction.

The present study was performed to investigate whether modes of voluntary contraction have an influence on an appearance of the premovement silent period (PSP) and components of the premovement cortical potentials. The EMG and the EEG were simultaneously recorded in an isometric ballistic contraction for exerting rapidly an elbow extension force and in a ballistic contraction for fast extending an elbow joint. The prime mover in the 2 contraction modes was the triceps brachii muscle. The frequency of the PSP was significantly higher in the isometric ballistic contraction than in the ballistic contraction (P < 0.01). The duration of the PSP was significantly longer in the isometric ballistic contraction than in the ballistic contraction (P < 0.01). In the isometric ballistic contraction, the 3 premovement cortical potentials (FNP, SNP and TNP) were identified. However, in the ballistic contraction the TNP did not appear. The PSP occurred in the phase of the TNP. The results obtained suggest that the PSP and the TNP are related to a more forceful contraction with faster rates of contraction, rather than only to speed of muscular contraction.

Action Potentials↗
PubMed1993

Potentials recorded from neck and supraclavicular fossa during a rapid voluntary contraction of the triceps brachii muscle.

Two experiments were performed in order to study whether it is possible to record potentials related to the voluntary movement from electrodes placed on the skin overlying the spinous process of the 2nd and 6th cervical vertebrae and at Erb's point ipsilateral to the movement. In the first series of experiments (Experiment I) the subject initiated spontaneously an arm movement accompanying a contraction of the right triceps brachii muscle. Rapid extension of the right 5 fingers was also performed self paced. Recordings of the potentials were referential to the left knee. The morphology of the potentials from the neck and Erb's point did not differ among time constants, between experimental days, among subjects and between the arm movement and the finger movement. A negative deflection of the cervical potential started preceding the onset of the electromyogram (EMG). This negativity was followed by a positive deflection after the EMG onset. The positive potential was followed by a negative deflection during the rising phase of the EMG. In the second series of experiments the subject performed both reaction and self-paced arm movements. The prime mover was the same as the agonist in Experiment I. Morphology of the potentials recorded with monopolar and bipolar derivations did not differ between the differently initiated movements and among the subjects. The morphology of the potentials from the neck and Erb's point was the same as the morphology of the potentials recorded in Experiment I. The present results indicate that it is possible to record the potentials related to the voluntary movement from neck and supraclavicular fossa.

Adult↗
PubMed1987

Temporal relationships of EMG changes preceding voluntary movement to premovement cortical potential shifts.

The silent period and a rhythmic slower wave in EMG appear preceding a rapid voluntary movement (Tanii 1984). The present study was performed to investigate temporal relationships of the EMG changes preceding movement to premovement cortical potential shifts, in order to clarify whether the EMG changes are related to preparation and initiation of voluntary movement. A strong push of a hard band with the right wrist was conducted rapidly following a slightly sustained contraction. The surface EMG was detected from the right triceps brachii muscle. The EEG was recorded from C3, Cz and C4. Slowing of the EMG occurred before the movement in addition to the slower wave. The EMG slower waves were accompanied by a negative deflection of raw EEG potentials. The averaged cortical potentials preceding movement fell into 3 negative potentials. The first potential started about 1.0 sec before the EMG burst. Many of the EMG slower waves occurred in the phase of the second potential occurring 330-510 msec before the EMG burst. Premovement silent period appeared in the phase of the third potential occurring 30-60 msec before the EMG burst. Amplitude of these potentials was larger in the contralateral hemisphere than in the ipsilateral one. This asymmetry became statistically significant in the phase of the second potential. The results suggest that the EMG slower waves and the premovement silent period are associated with preparation and initiation of voluntary movement.

Adult↗
PubMed1986

Changes in activity of motor units preceding a rapid voluntary movement.

Motor unit activity was studied during slightly sustained contraction of the erector spinal muscle before a rapid trunk extension from a moderately bent position, with special reference to a change of the surface EMG to a rhythmic slower wave with a periodicity of 20-30 msec preceding the movement. Synchronous discharge of a few motor units appeared at regular intervals of 20-30 msec during the slower wave. EMG peaks in the slower wave corresponded to synchronous discharges at the regular intervals.

Electromyography↗
PubMed1985

Power spectral analysis of the surface electromyogram before and after a warning signal in a reaction movement.

The present study was performed to substantiate the premise that frequency components of the surface EMG before a reaction movement change after a warning signal (S1). Twelve subjects extended rapidly the trunk from a bent position in response to a moving signal (S2) 2 sec after S1. The movement was repeated 20 times. Bipolar surface EMG recordings were made from the erector spinal muscle. A minicomputer calculated power spectra of the surface EMGs for 2 sec before S1 and for 2 sec from S1 until S2 in each trial. From each spectrum, the mean frequency (MF) was calculated. EMG itself was examined. Statistical comparisons of differences between the mean values of the MF before and after S1 showed that a significant difference was found in 5 subjects. For the subjects, the mean value of the MF after S1 was a lower value than that of the MF before S1. Increase of EMG power in frequency range from 30 to 50 Hz was observed in the averaged EMG spectrum after S1 in the subjects. Slowing of the surface EMG during the preparatory period from S1 until S2 was often observed in the subjects. These results show that the power spectrum of the surface EMG after S1 shifted to lower frequencies and suggest that the EMG spectral shift is due to the slowing of the surface EMG in association with motor preparation to perform the movement.

Electromyography↗
PubMed1984

Occurrence of a rhythmic slower wave in EMG prior to a rapid voluntary movement.

The aim of the present study was to investigate whether an EMG slower wave prior to a rapid straightening-up movement is associated with motor preparation to perform the movement. The straightening movement was performed at 6 load intensities and under 3 conditions: without any external load; with an additional load; lifting a load. The subject could freely begin the rapid movement from a moderate forward-bending position whenever he was fully ready for the beginning of the movement after he held the bent posture. Bipolar surface EMGs of the erector spinal muscles at the L1 and L4 level, the gluteus maximus muscle and the semitendinosus muscle were led by a pair of skin electrodes with a time constant of 0.03 sec. The signal from the hip goniometer was measured simultaneously to identify the period of the movement. A distinct relationship between the occurrence of the slower wave and both load intensities and conditions was not found. However, the rhythmic slower wave often occurred in the muscles 200-450 msec before the movement. The occurrence of the wave in the muscles was often simultaneous. The signal from the hip goniometer did not change with the occurrence of the slower wave. The amplitude of the slower wave increased frequently. The present results suggest that the slower wave may reflect a significant change of motoneuronal activity in connection with motor preparation to perform the movement.

Adult↗
PubMed1976

Spontaneous alternation of the working arm in one-arm cranking.

One-arm cranking was done by ten healthy male adults at an oxygen intake level of about 1.0 liter/min. Each subject performed two kinds of cranking at a speed of 60 rpm: forced cranking using only one arm continuously for 15 min and free cranking for 30 min with the instructions to alternate from one arm to the other whenever fatigue set in. The results, excluding those of a subject who changed arms very frequently, were analyzed. In forced cranking, oxygen intake and heart rate steadily increased, the average time of appearance of local fatigue being 161 sec for the stronger arm and 122 sec for the weaker one. In free cranking, the working arm was changed 6 to 23 times during the 30-minute period, while oxygen intake and heart rate increased with fluctuations. The mean duration interval was 175 sec with the stronger arm and 123 sec with the weaker one. The mean interval of arm alternation was positively correlated with the individual time of onset of the sensation of local rigidness during forced cranking, but not with the individual time of initiation of respiratory distress. It is suggested that alternation of active muscles in moderately dynamic work may be linked with an early stage of local fatigue which is different from that of static work.

Adult↗