Papers by Kuniyasu Imanaka
Human Movement Science, Jun 1, 2011
Perceptual and Motor Skills, Oct 1, 1995
With 6 male subjects we investigated whether the decreased amplitude in the frontal N30 potential... more With 6 male subjects we investigated whether the decreased amplitude in the frontal N30 potential of Somatosensory Evoked Potentials is related to a sustained voluntary movement or not. We concluded that the diminution of frontal N30 was also closely related to the sustained voluntary movement.
International Journal of Rehabilitation Research, Dec 1, 2016
The lateral body weight-shifting task is commonly used in therapeutic programs for patients with ... more The lateral body weight-shifting task is commonly used in therapeutic programs for patients with orthopedic complaints or hemiparesis. Although the patients usually support themselves using the upper limbs during the task, it is unclear whether the use of upper limbs affects performance accuracy of lateral body weight shifting. Therefore, the aim of this study was to investigate the effects of support by the upper limbs on performance accuracy, particularly on the central tendency effects (i.e. overshooting for light targets and undershooting for heavy targets). Twenty-three able-bodied, neurologically intact individuals, who were right-handed and right-footed participants performed the lateral body weight-shifting task to shift one-third or two-thirds of their body weight toward the left and right lower limbs using support by the upper limbs. The result of correlation coefficients between interlimb weight adjustment and errors showed that the use of the upper limbs and interlimb weight adjustment related to the enhanced central tendency effects. The use of upper limbs generally contributes toward stabilizing posture, however, this is not the case with performance of the lateral body weight shifting. Moreover, the effects of using the upper limb on performance accuracy differed among leftward and rightward weight shifting. This result might be owing to the dominant side of the hand/foot and hemisphere lateralization.
Frontiers in Psychology, Sep 24, 2021
The purposes of the present study were threefold: to examine (a) if the movementspecific reinvest... more The purposes of the present study were threefold: to examine (a) if the movementspecific reinvestment responses should be represented as two dimensional constructs, (b) whether dichotomization of the movement-specific reinvestment responses are appropriate, and (c) how the two dimensions are associated with relevant psychological concepts. To conduct a comparative examination of the MSRS structure in two Asian samples, participants were 236 Japanese university students (136 men, 100 women; M age = 18.0, SD = 1.6) and 328 Singaporeans (167 men, 161 women; M age = 21.8, SD = 1.8). After examining the factor structure of the movement-specific reinvestment responses for the first purpose, latent class factor analysis was conducted for both samples for the second purpose. For the third purpose, correlation analysis and mediation analysis were conducted for a part of the Singaporean sample. Through a series of latent class factor analysis, four and three classes were identified for the Japanese and Singaporean samples, respectively. For both samples, the patterns of the item-average scores for the two movement-specific reinvestment dimensions were parallel among the classes. Conscious Motor Processing was positively associated with mental toughness, intrinsic regulation, integrated regulation, mastery-approach and task goal orientations, and dispositional flow, whereas Movement Self-Consciousness was positively related with stress and mastery-avoidance goal orientation. The findings of the study supported (a) the two-dimensional representation of the movement-specific reinvestment responses, but did not fully support (b) the practice of dichotomization of the movement-specific reinvestment responses, and indicated that (c) at the trait level, Conscious Motor Processing and Movement Self-Consciousness were associated with positive and negative psychological constructs, respectively.
John Benjamins Publishing Company eBooks, 2000
Attention, perception & psychophysics, Aug 15, 2014
We investigated the effects of pursuit effort against the optokinetic nystagmus (OKN) on induced ... more We investigated the effects of pursuit effort against the optokinetic nystagmus (OKN) on induced motion (IM) by measuring vertical IM and eye movements. Participants viewed an inducing stimulus (a random dot pattern) moving either upward or downward at the velocity of 10 or 40°/s. A horizontally moving target (a single dot) was then presented within the inducing stimulus. Participants were asked to pursue the target and report the perceived slant of the target motion path by using a joystick. The results showed that IM magnitude was larger with an upward stimulation than with a downward stimulation. IM magnitude was also larger at 40°/s than at 10°/s. The results of eye movements prior to the target presentation showed that OKN was elicited more effectively with an upward stimulation than with a downward stimulation and at 40°/s than at 10°/s. OKN was markedly reduced when the target was presented within the inducing stimulus. These results support the oculomotor theory that IM magnitude reflects pursuit effort against OKN in response to an inducing stimulus.
Applied human science, 1998
The purpose of this study was to determine whether the hypothesis on the levels of psychological ... more The purpose of this study was to determine whether the hypothesis on the levels of psychological processes (Hatta, 1977, 1978) accounts for lateral differences in arm positioning movement (a spatial localization task). Fifteen right-handed male subjects were asked to perform a constrained criterion movement, 12 cm in length, with the left or right arm. Then, after a 10-sec retention interval, they were asked to perform the movement with the same arm, estimating lengths of 6, 12 or 24 cm. Different levels of psychological processes were assumed to be involved in estimating these various movement lengths-half, the same, or double that of the original. All possible combinations of the arm (left/right) and three movement length were tested. The CE scores were lower (more accurate) for the left arm (half; 1.5 ± 8.1 mm, same; 4.3 ± 6.2 mm, double; 5.9 ± 20.3 mm) than those for the right arm (half; 5.9 ± 7.6 mm, same; 10.6 ± 10.6 mm, double; 11.8 ± 23.6 mm) in all conditions, indicating a lateral difference (the right hemisphere dominance) in arm positioning tasks. This typical lateral difference, which displayed no significant difference among conditions, is supposed to be mediated by complex or high-level psychological processes. These psychological processes are required by the subjects in the estimation of the various movement lengths. This study suggests that the level of psychological processes is a crucial factor in the manifestation of lateral differences in the performance of arm positioning movements.
The Journals of Gerontology: Series B, Dec 6, 2020
Objectives There is a growing body of literature examining age-related overestimation of one’s ow... more Objectives There is a growing body of literature examining age-related overestimation of one’s own physical ability, which is a potential risk of falls in older adults, but it is unclear what leads them to overestimate. This study aimed to examine 3-year longitudinal changes in self-estimated step-over ability, along with one key risk factor: low frequency of going outdoors (FG), which is a measure of poor daily physical activity. Method This cohort study included 116 community-dwelling older adults who participated in baseline and 3-year follow-up assessments. The step-over test was used to measure both the self-estimated step-over bar height (EH) and the actual bar height (AH). Low FG was defined as going outdoors either every few days or less at baseline. Results The number of participants who overestimated their step-over ability (EH > AH) significantly increased from 10.3% to 22.4% over the study period. AH was significantly lower at follow-up than at baseline in both participants with low and high FGs. Conversely, among participants with low FG, EH was significantly higher at follow-up than at baseline, resulting in increased self-estimation error toward overestimation. Regression model showed that low FG was independently associated with increased error in estimation (i.e., tendency to overestimate) at follow-up. Discussion The present study indicated that self-overestimated physical ability in older adults is not only due to decreased physical ability but also due to increased self-estimation of one’s ability as a function of low FG. Active lifestyle may be critical for maintaining accurate estimations of one’s own physical ability.
European Journal of Applied Physiology, 1994
In the present study, we investigated whether weak (10% of maximal voluntary contraction) tonic d... more In the present study, we investigated whether weak (10% of maximal voluntary contraction) tonic dorsiflexion (DF) and plantarflexion (PF) affects the two conventional parameters used for evaluating the excitability of the soleus motoneuron (MN) pool, i.e. the ratio of the threshold of H-reflex to that of M-response (Hth:Mth) and the ratio of the maximal amplitude of H-reflex to that of M-response (Hmax:Mmax) in human subjects. The results showed that the Hmax:Mmax decreased during DF and increased during PF compared with that during rest, whereas no clear alteration was observed in Hth:Mth. These results are consistent with the scheme proposed by earlier workers, who have argued that neither inhibitory nor facilitatory effects of the conditioning stimulus apply to specific spinal reflex circuits occurring around the threshold of the test H-reflex. It is suggested, therefore, that the conventional use of the Hth:Mth ratio as a parameter reflecting the excitability of the MN pool should be reconsidered.
Human Movement Science, Dec 1, 2002
The effects of preparatory weak muscular contraction (pre-tension) have been investigated in a nu... more The effects of preparatory weak muscular contraction (pre-tension) have been investigated in a number of previous studies using tasks with either simple or choice responses to measure the reaction time (RT). These studies suggested that optimal pre-tension performed prior to a motor response tends to shorten the RTs. Using a simple RT task in which participants performed a grip response to a visual stimulus, the present study compared the RTs between two pre-tension conditions (self-selection and constraint) to investigate the effects of different instructions for pre-tension. Under the self-selection condition, participants were asked to determine their optimal pre-tension levels while attempting to give responses as fast as possible. Under the constraint condition, the participants developed a pre-tension at a target force determined by the experimenter. The target force was set at the same level as the pre-tension level maintained under the self-selection. Despite the fact that the pre-tension level manipulated was the same for both conditions, the RTs were significantly shorter under self-selection than under constraint. Moreover, the present study showed a positive correlation coefficient between the proportion of shortening in RT and the variation of pre-tension level. This indicated a performance trade-off between the stability of pre-tension and RTs. The result suggests that shorter RTs that occur under self-selection are primarily mediated by mental factors, such as attention allocation, rather than by the effects of peripheral muscular preparation.
Attention, perception & psychophysics, Dec 25, 2014
Sports involving fast visual perception require players to compensate for delays in neural proces... more Sports involving fast visual perception require players to compensate for delays in neural processing of visual information. Memory for the final position of a moving object is distorted forward along its path of motion (i.e., "representational momentum," RM). This cognitive extrapolation of visual perception might compensate for the neural delay in interacting appropriately with a moving object. The present study examined whether experienced batters cognitively extrapolate the location of a fast-moving object and whether this extrapolation is associated with coincident timing control. Nine expert and nine novice baseball players performed a prediction motion task in which a target moved from one end of a straight 400-cm track at a constant velocity. In half of the trials, vision was suddenly occluded when the target reached the 200-cm point (occlusion condition). Participants had to press a button concurrently with the target arrival at the end of the track and verbally report their subjective assessment of the first target-occluded position. Experts showed larger RM magnitude (cognitive extrapolation) than did novices in the occlusion condition. RM magnitude and timing errors were strongly correlated in the fast velocity condition in both experts and novices, whereas in the slow velocity condition, a significant correlation appeared only in experts. This suggests that experts can cognitively extrapolate the location of a moving object according to their anticipation and, as a result, potentially circumvent neural processing delays. This process might be used to control response timing when interacting with moving objects.
The Quarterly journal of experimental psychology, Nov 1, 1992
A number of researchers (e.g. Kerr, 1978; Walsh, Russell, Imanaka, & James, 1979) have previously... more A number of researchers (e.g. Kerr, 1978; Walsh, Russell, Imanaka, & James, 1979) have previously demonstrated interference between location and distance information in motor short-term memory. This interference manifests itself in a characteristic pattern of undershooting and overshooting, with reproduction movement location being drawn in the direction of criterion movement distance and, conversely, the distance of reproduction movements being influenced by the terminal location of the criterion movement. We investigated the effects of different cognitive strategies upon the appearance of this location-distance interference during the reproduction of movement location (Experiment 1) and distance (Experiments 2 and 3) in a linear arm positioning task. Experiment 1 compared performance in location reproduction between two strategy groups differing in the availability of explicit information about the change in starting position. The characteristic undershooting-overshooting interference pattern was observed for the group without the explicit information about the change in starting position but disappeared for the group in which explicit information about the change in starting position was provided. Experiment 2 examined the systematic undershooting-overshooting pattern in distance reproduction for a location strategy (involving some extrapolation of the start and end locations), a counting strategy, and a distance sense strategy (involving the use of visual imagery). The systematic response bias pattern disappeared when the subjects used a location strategy but was clearly observed for the subjects using the other two strategies. This finding was generally confirmed by Experiment 3, which showed a typical undershooting-overshooting pattern in distance reproduction for a counting/distance sense strategy but not for two location strategies (a general location and an explicit location strategy). The location strategies differed in the availability of explicit information about starting and end locations for both the criterion and reproduction movements. The results Request for reprints should be sent to K. Imanaka, Faculty of Liberal Arts, Nagasaki The experiments reported in this paper formed part of the first author's doctoral dis
Journal of Nutrition Health & Aging, Sep 30, 2016
walking. Since MI has been shown to decline with aging (19-21) and to be associated with dysfunct... more walking. Since MI has been shown to decline with aging (19-21) and to be associated with dysfunctions in gait related tasks (20), we hypothesize that deficits in MI of the Timed Up and Go (TUG) test will be more evident in older adults with FoF. Methods
European Journal of Applied Physiology, Mar 21, 2001
In the present study, we examined the electromyogram (EMG) patterns of the soleus and medial gast... more In the present study, we examined the electromyogram (EMG) patterns of the soleus and medial gastrocnemius (MG) muscles during rhythmical, two-legged hopping to investigate the contributions of the monosynaptic short- and long-latency stretch reflexes during such a natural movement in human. During rhythmical hopping, soleus muscle is activated reflexly at near-monosynaptic latency by stretch resulting from passive ankle flexion upon landing. Soleus muscle also contracts voluntarily in order to launch the body into the next hop. This is part of the rhythmical bursts of activity producing the hops. Depending on the hopping interval, this phase of activation can follow the short-latency phase or precede landing at very short hopping intervals. In MG, there is an initial phase of activity that stiffens the muscle in preparation for landing, and continues through the contact phase. The monosynaptic reflex response to landing is usually superimposed on this activity. Depending on the hopping interval, both of these responses may be overlaid with activity that is time-locked to the take-off into the next hop, and serves to launch the body into the next hop. However, no evidence for a long-latency stretch reflex was found. In addition, the preferred hopping frequency for all subjects was about 2 Hz. This frequency is associated with a pattern of EMG activity the timing of which indicates that it balances the requirement for a comfortable landing from a hop with the optimal muscle activation required for launching the following hop.
Advances in exercise and sports physiology, Feb 1, 2013
Advances in exercise and sports physiology, 1999
Human Movement Science, Dec 1, 2002
The present study reviews the literature on the empirical evidence for the dissociation between p... more The present study reviews the literature on the empirical evidence for the dissociation between perception and action. We first review several key studies on brain-damaged patients, such as those suffering from blindsight and visual/tactile agnosia, and on experimental findings examining pointing movements in normal people in response to a nonconsciously perceived stimulus. We then describe three experiments we conducted using simple reaction time (RT) tasks with backward masking, in which the first (weak) and second (strong) electric stimuli were consecutively presented with a 40-ms interstimulus interval (ISI). First, we compared simple RTs for three stimulus conditions: weak alone, strong alone, and double, i.e., weak plus strong (Experiment 1); then, we manipulated the intensity of the first stimulus from the threshold (T) to 1:2T and 2T , with the second stimulus at 4T (Experiment 2); finally, we tested three different ISIs (20, 40, and 60 ms) with the stimulus intensities at 1:2T and 4T for the first and second stimuli (Experiment 3). These experiments showed that simple RTs were shorter for the double condition than for the strong-alone condition, indicating that motor processes under the double condition may be triggered by sensory inputs arising from the first stimulus. Our results also showed that the first stimulus was perceived without conscious awareness. These findings suggested that motor processes may be dissociated from conscious perceptual processes and that these two processes may not take place in a series but, rather, in parallel. We discussed the likely mechanisms underlying nonconscious perception and motor response to a nonconsciously perceived stimulus.
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Papers by Kuniyasu Imanaka