Search tips
Search criteria

Results 1-5 (5)

Clipboard (0)

Select a Filter Below

more »
Year of Publication
Document Types
1.  Visuomotor Map Determines How Visually Guided Reaching Movements are Corrected Within and Across Trials123 
eNeuro  2016;3(3):ENEURO.0032-16.2016.
When a visually guided reaching movement is unexpectedly perturbed, it is implicitly corrected in two ways: immediately after the perturbation by feedback control (online correction) and in the next movement by adjusting feedforward motor commands (offline correction or motor adaptation). Although recent studies have revealed a close relationship between feedback and feedforward controls, the nature of this relationship is not yet fully understood. Here, we show that both implicit online and offline movement corrections utilize the same visuomotor map for feedforward movement control that transforms the spatial location of visual objects into appropriate motor commands. First, we artificially distorted the visuomotor map by applying opposite visual rotations to the cursor representing the hand position while human participants reached for two different targets. This procedure implicitly altered the visuomotor map so that changes in the movement direction to the target location were more insensitive or more sensitive. Then, we examined how such visuomotor map distortion influenced online movement correction by suddenly changing the target location. The magnitude of online movement correction was altered according to the shape of the visuomotor map. We also examined offline movement correction; the aftereffect induced by visual rotation in the previous trial was modulated according to the shape of the visuomotor map. These results highlighted the importance of the visuomotor map as a foundation for implicit motor control mechanisms and the intimate relationship between feedforward control, feedback control, and motor adaptation.
PMCID: PMC4891765  PMID: 27275006
feedback control; feedforward control; motor adaptation; reaching movement; visuomotor map
2.  Improving a Bimanual Motor Skill Through Unimanual Training 
When we learn a bimanual motor skill (e.g., rowing a boat), we often break it down into unimanual practices (e.g., a rowing drill with the left or right arm). Such unimanual practice is thought to be useful for learning bimanual motor skills efficiently because the learner can concentrate on learning to perform a simpler component. However, it is not so straightforward to assume that unimanual training (UT) improves bimanual performance. We have previously demonstrated that motor memories for reaching movements consist of three different parts: unimanual-specific, bimanual-specific, and overlapping parts. According to this scheme, UT appears to be less effective, as its training effect is only partially transferred to the same limb for bimanual movement. In the present study, counter-intuitively, we demonstrate that, even after the bimanual skill is almost fully learned by means of bimanual training (BT), additional UT could further improve bimanual skill. We hypothesized that this effect occurs because UT increases the memory content in the overlapping part, which might contribute to an increase in the memory for bimanual movement. To test this hypothesis, we examined whether the UT performed after sufficient BT could improve the bimanual performance. Participants practiced performing bimanual reaching movements (BM) in the presence of a novel force-field imposed only on their left arm. As an index for the motor performance, we used the error-clamp method (i.e., after-effect of the left arm) to evaluate the force output to compensate for the force-field during the reaching movement. After sufficient BT, the training effect reached a plateau. However, UT performed subsequently improved the bimanual performance significantly. In contrast, when the same amount of BT was continued, the bimanual performance remained unchanged, highlighting the beneficial effect of UT on bimanual performance. Considering memory structure, we also expected that BT could improve unimanual performance, which was confirmed by another experiment. These results provide a new interpretation of why UT was useful for improving a bimanual skill, and propose a practical strategy for enhancing performance by performing training in various contexts.
PMCID: PMC4944083  PMID: 27471452
unimanual movement; bimanual movement; reaching movement; context-dependent motor memories; motor adaptation; learning transfer; whole and part practice
3.  Clinical characteristics and risk factors for septic shock in patients receiving emergency drainage for acute pyelonephritis with upper urinary tract calculi 
BMC Urology  2012;12:4.
Acute pyelonephritis (APN) is a common complication of ureteral obstruction caused by urolithiasis, and it can be lethal if it progresses to septic shock. We investigated the clinical characteristics of patients undergoing emergency drainage and assessed risk factors for septic shock.
A retrospective study was performed of 98 patients (101 events) requiring emergency drainage at our urology department for obstructive APN associated with upper urinary tract calculi from January 2003 to January 2011. Clinical characteristics were summarized, and risk factors for septic shock were assessed by logistic regression analysis.
Objective evidence of sepsis was found in 64 (63.4%) events, and 21 events (20.8%) were categorized as septic shock. Ninety-six patients recovered, but 2 patients died of septic shock. Multivariate analysis revealed that age and the presence of paralysis were independent risk factors for septic shock.
APN associated with upper urinary tract calculi is a severe disease that should be treated with caution, particularly when risk factors are present.
PMCID: PMC3353222  PMID: 22413829
4.  Involvement of medial temporal structures in reflexive attentional shift by gaze 
Recent studies have revealed that eye gaze triggers reflexive shift of the observer's visuospatial attention to its direction even if it does not predict any events in the environment. To determine whether medial temporal structures are involved in this reflexive gaze processing, an experiment of the gaze-cuing paradigm was carried out in seven epileptic patients who had undergone unilateral temporal lobectomy and nine age- and IQ-matched epileptic controls who had not undergone any surgical treatments. Gaze cues were presented for 200 ms to the unilateral visual field, after which subjects were required to localize targets as quickly as possible. They were also instructed that gaze directions were not predictive of the location of the targets. When the gaze cues stimulated the intact hemisphere in lobectomized patients or either hemisphere in controls, reaction times for correct responses were significantly shorter when gaze directions were toward the targets than away from the targets. This cuing effect was not manifested following stimulation of the lesioned hemisphere in lobectomized patients. These findings suggest that the medial temporal structures, including the amygdala, play a crucial role in the reflexive shift of attention triggered by another person's gaze direction in humans.
PMCID: PMC2569822  PMID: 19015098
medial temporal structures; gaze direction; reflexive attentional shift; cuing paradigm; anterior temporal lobectomy; unilateral visual field presentation
5.  Effects of milnacipran on binge eating – a pilot study 
Selective serotonin reuptake inhibitors and selective norepinephrine reuptake inhibitors are effective in the treatment of bulimia nervosa. There have been relatively few studies of the efficacy of specific serotonin and norepinephrine reuptake inhibitors in the treatment of eating disorders. Twenty-five outpatients with binge eating episodes, diagnosed as anorexia nervosa, binge-eating/purging type, bulimia nervosa/purging type, or bulimia nervosa/non-purging type, were treated with milnacipran and 20 patients completed the 8-week study. Symptom severity was evaluated using the Bulimic Investigatory Test, Edinburgh (BITE) self-rating scale before administration of milnacipran and after 1, 4, and 8 weeks treatment. The scores improved after 8 weeks, especially drive to, and regret for, binge eating. Milnacipran was more effective in patients without purging and in younger patients, while there was no difference in the efficacy of milnacipran among subtypes of eating disorders.
PMCID: PMC2515919  PMID: 18728825
milnacipran; specific serotonin and norepinephrine reuptake inhibitors; binge eating; vomiting; eating disorder; pharmacotherapy

Results 1-5 (5)