Shu Morioka

Influence of transcranial direct current stimulation of the dorsolateral prefrontal cortex on pain related emotions: a study using electroencephalographic power spectrum analysis.

Pain is a multidimensional experience with sensory-discriminative, cognitive-evaluative and affective-motivational components. Emotional factors such as unpleasantness or anxiety are known to have influence on pain in humans. The aim of this single-blinded, cross over study was to evaluate the effects of transcranial direct current stimulation (tDCS) on emotional aspects of pain in pain alleviation. Fifteen subjects (5 females, 10 males) volunteered to participate in this study. In an oddball paradigm, three categories of 20 pictures (unpleasant, neutral, and pleasant) served as rare target pictures from the International Affective Picture System (IAPS). The power of the delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-25 Hz), and gamma (30-40 Hz) frequency bands in the three categories were measured using electroencephalography during an oddball paradigm at pre- and post-anodal or sham tDCS above the left dorsolateral prefrontal cortex (DLPFC). Results showed that the beta band power was significantly increased, and the alpha band power was significantly decreased during unpleasant pictures after anodal tDCS compared with sham tDCS. Furthermore, regarding unpleasant pictures, subjective reports of Self Assessment Manikin (SAM) for emotional valence after anodal tDCS showed a significant decrease of unpleasantness. Therefore, emotional aspects of pain may be effectively alleviated by tDCS of the left DLPFC as was shown not only by subjective evaluation, but also by objective observation of cerebral neural activity. This processing may be mediated by facilitation of the descending pain inhibitory system through enhancing neural activity of the left DLPFC.

Effects of dual task balance training on dual task performance in elderly people: a randomized controlled trial:

Objective: To investigate the effects of dual task balance training in the elderly on standing postural control while performing a cognitive task. Design: A randomized two-group parallel controlled trial. Participants: Forty-three subjects (all >65 years old) were enrolled in the study and were assigned randomly to either an experimental group (n = 21) or a control group (n = 22). Interventions: Subjects in the experimental group were given strength and balance training while performing cognitive tasks simultaneously. Subjects in the control group were given strength and balance training only. The training was administered twice a week for three months. Measurements: The Chair Stand Test, Functional Reach Test, Timed Up and Go Test and Trail Making Test were measured. The sway length of the centre of gravity was measured during standing while performing the Stroop task. The rate of Stroop task was also measured. All measurements were collected at baseline and after the training period. Results: There were no significant differences in Functional Reach Test, Timed Up and Go Test and sway length at baseline and after training between the two groups. However, the rate of Stroop task (P < 0.05) was significantly higher after training in the experimental group than in the control group. Conclusions: These results suggest that dual task balance training in elderly people improves their dual task performance during standing postural control.

Effects of perceptual learning exercises on standing balance using a hardness discrimination task in hemiplegic patients following stroke: a randomized controlled pilot trial

Objective: To investigate the effect of perceptual learning exercises for hardness discrimination by the soles on standing balance in stroke patients with hemiplegia. Subjects: Twenty-eight subjects were randomly assigned to an experimental or a control group and participated in a rehabilitation programme. Intervention: The experimental group received perceptual learning exercises on hardness discrimination using three different levels of hardness of a rubber sponge for 10 days. Main measures: Length, enveloped area and rectangular area of the parameter of postural sway were measured by a stabilometer on entry into the study and after 10 days. Results: Twenty-six subjects completed the study. Data indicate that more parameters indicating postural sway were significantly decreased in the experimental group than in the control group. Also, there was a significant difference between the groups in change scores (pre-exercise minus postexercise) of length and enveloped area. Conclusion: The plantar perception exercise used as a method in this study is considered to be effective as a supplemental exercise for standing balance. The possibility of clinical application using the hardness discrimination task with rubber as a balance exercise is therefore suggested.

Influence of perceptual learning on standing posture balance: repeated training for hardness discrimination of foot sole

The current study investigated the influence of perceptual learning training for hardness discrimination of sponge rubber by the soles on postural sway. Subjects consisted of 30 healthy male volunteers. They were divided into two groups of 15 each at random: perceptual learning training group and a control group. For hardness discrimination training, rubber sponges 5, 10, and 20 mm thick were combined to change the thickness of rubber to 5, 10, 15, 20, and 25 mm. The hardness discrimination training was administered with eyes closed in the standing position for each day for 10 days. The center of pressure measured using a stabilometer was used as the indicator for postural sway. Postural sway was measured for 30 s with eyes open and closed before and after hardness discrimination training. Statistical analysis was performed for length, enveloped area, and rectangular area. Postural sway after training showed a significant decrease compared to sway before training in the perceptual learning training group. However, there was no change on postural sway in the control group. In conclusion, data indicate that the ability of the healthy subjects to regulate their standing posture improved with improvement of the perceptive ability of the soles.

Negative body image associated with changes in the visual body appearance increases pain perception.

Changing the visual body appearance by use of as virtual reality system, funny mirror, or binocular glasses has been reported to be helpful in rehabilitation of pain. However, there are interindividual differences in the analgesic effect of changing the visual body image. We hypothesized that a negative body image associated with changing the visual body appearance causes interindividual differences in the analgesic effect although the relationship between the visual body appearance and analgesic effect has not been clarified. We investigated whether a negative body image associated with changes in the visual body appearance increased pain. Twenty-five healthy individuals participated in this study. To evoke a negative body image, we applied the method of rubber hand illusion. We created an “injured rubber hand” to evoke unpleasantness associated with pain, a “hairy rubber hand” to evoke unpleasantness associated with embarrassment, and a “twisted rubber hand” to evoke unpleasantness associated with deviation from the concept of normality. We also created a “normal rubber hand” as a control. The pain threshold was measured while the participant observed the rubber hand using a device that measured pain caused by thermal stimuli. Body ownership experiences were elicited by observation of the injured rubber hand and hairy rubber hand as well as the normal rubber hand. Participants felt more unpleasantness by observing the injured rubber hand and hairy rubber hand than the normal rubber hand and twisted rubber hand (p<0.001). The pain threshold was lower under the injured rubber hand condition than with the other conditions (p<0.001). We conclude that a negative body appearance associated with pain can increase pain sensitivity.

the relationship among psychological factors, neglect-like symptoms and postoperative pain after total knee arthroplasty

Neglect-like symptoms have been defined as a loss of perception of a limb, with pain and excessive effort necessary to move the limb. This phenomenon has been studied in patients with complex regional pain syndrome, but has not been assessed in patients who have undergone orthopedic procedures such as total knee arthroplasty. The authors of this study assessed neglect-like symptoms in a group of 90 patients three and six weeks after total knee arthroplasty.

Enhancement of precise hand movement by transcranial direct current stimulation.

The effect of transcranial direct current stimulation (tDCS) on the precise nondominant hand movement was investigated by applying anodal stimulation over the right primary motor cortex. We recruited 14 healthy participants for this single-blind, sham-controlled crossover trial. A circle-drawing task was performed before, immediately after, and at 30 min after 20 min of 1 mA anodal or sham tDCS. Anodal tDCS, compared with sham stimulation, significantly improved the circle-drawing task compared with sham stimulation. The deviation area and path length of the task were significantly decreased after anodal tDCS application and were further enhanced at 30 min after stimulation. These results suggest that anodal tDCS over the primary motor cortex enhances the precise movement of the nondominant hand for 30 min in healthy participants.

Factors associated with the modulation of pain by visual distortion of body size

Modulation of pain using visual distortion of body size (VDBS) has been the subject of various reports. However, the mechanism underlying the effect of VDBS on pain has been less often studied. In the present study, factors associated with modulation of pain threshold by VDBS were investigated. Visual feedback in the form of a magnified image of the hand was provided to 44 healthy adults to examine changes in pain. In participants with a higher pain threshold when visual feedback of a magnified image of the hand was provided, the two-point discrimination threshold decreased. In contrast, participants with a lower pain threshold with visual feedback of a magnified image of the hand experienced unpleasant emotions toward the magnified image of the hand. Interestingly, this emotional reaction was strongly associated with negative body consciousness in several subjects. These data suggested an analgesic effect of visual feedback in the form of a magnified image of the hand is only when tactile perception is vivid and the emotional reaction toward the magnified image is moderate. The results also suggested that negative body consciousness is important for the modulation of pain using VDBS.

A new simple performance test focused on agility in elderly people: The Ten Step Test.

Background: Not only the reduction of muscle strength or balance, but also the reduction of the agility are regarded as important factors of falls in elderly people. If an agility test for elderly people is established, the precision of the fall prediction rises and can be used for individual training. Objectives: To develop a new performance test focused on agility for elderly people and to evaluate the usefulness of this test. Design: Cross-sectional study. Setting: The Welfare Center of Kagami Town, Kagami Town Office, etc., Kochi, Japan. Participants: 828 community-dwelling, independent adults aged 20–99 years with no obvious cognitive or functional disability, were randomly recruited from Kagami town and the surrounding areas. Measurements: The Ten Step Test (TST, a new performance test), motor reaction time (MRT), knee extensor isometric strength, single leg standing time (SLST), and some other tests were used to evaluate the criterion-related validity and the content validity. TST was developed as a modified version of other step tests which require the subjects to place the whole foot on a block, then return it to the floor. In addition, female participants over 70 were asked whether or not they had fallen in the past year. Results: Excellent reliability for TST was found for interrelation (intra-class correlation coefficients, ICC = 0.96), and re-test reliability was sufficient (ICC = 0.86). Evidence for criterion-related validity was found through high single correlation with the timed supine-to-stand (r = 0.68) and high single correlation with MRT (r = 0.59). In addition, content validity was found through low correlation with knee extensor strength (–0.35) and SLST (–0.36) in 112 women over 70 years of age. The error rate by TST to predict falls (35.2%) was lower than the error rate by muscle strength (44.4%) and the balance (38.7%). TST confirmed decline after 50 years of age, and it conformed to a cubic curve. Conclusion: The findings indicate that TST is a reliable measure of agility, and it can help to predict the risk of falls. The decline of agility accelerates after 50 years of age. It shows that the decline of agility differs from the decline of leg muscle strength and balance.

Effects of plantar perception training on standing posture balance in the old old and the very old living in nursing facilities: a randomized controlled trial

Objective: To determine whether plantar perception training using a hardness discrimination task efficiently improves stabilization of standing posture balance in the old old as well as the very old. Design: A randomized two-group parallel controlled trial. Setting: Nursing homes. Participants: Forty-six elderly persons 75 years of age or older living in nursing facilities were randomly assigned evenly to either an intervention or a control group. Intervention: The intervention group was given a task to discriminate hardness differences while standing on foam rubber of different levels of hardness, while the control group was given the task to simply remain standing on foam rubber. The tasks were imposed for 10 successive days. Outcome measures: Outcome assessment was made by determinations of centre-of-gravity sway in the standing position and the Functional Reach Test. Results: Planter perception was significantly improved and centre-of-gravity sway in the standing position was also significantly reduced in the intervention group after the intervention. In the control group, however, there were no significant changes in perception or in sway (P < 0.01) There was a significant difference in the Functional Reach Test values between the two groups: an increment of 12.3 ± 10.1 cm in the intervention group vs. 2.3 ± 5.8 cm in the control group (P < 0.001). Conclusion: These results suggested that plantar perception exercises might efficiently stabilize standing postural balance in the old old as well as the very old.