Hiroshi Ando

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.

Recovering Three-Dimensional Structure from Motion with Surface Reconstruction

This paper addresses the computational role that the construction of a complete surface representation may play in the recovery of 3-D structure from motion. We first discuss the need to integrate surface reconstruction with the structure-from-motion process, both on computational and perceptual grounds. We then present a model that combines a feature-based structure-from-motion algorithm with a smooth surface interpolation mechanism. This model allows multiple surfaces to be represented in a given viewing direction, incorporates constraints on surface structure from object boundaries, and segregates image features onto multiple surfaces on the basis of their 2-D image motion. We present the results of computer simulations that relate the qualitative behavior of this model to psychophysical observations. In a companion paper, we discuss further perceptual observations regarding the possible role of surface reconstruction in the human recovery of 3-D structure from motion.

Expression of the GABAB receptor in Xenopus oocytes and inhibition of the response by activation of protein kinase C

The functional GABAB receptor was expressed in Xenopus oocytes by injecting mRNA obtained from the cerebellum of the rat. Application of GABA in the presence of bicuculline induced a hyperpolarization under current‐clamp conditions and an outward current under voltage‐clamp conditions. Baclofen mimicked the effect of GABA in the presence of bicuculline, and the effect of baclofen was antagonized by phaclofen. The GABA‐induced outward current was slightly inhibited by treatment with GDP‐β‐S and was completely inhibited by treatment with GTP‐γ‐S. The activation of protein kinase C by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), but not 4α‐phorbol‐12,13‐didecanoate, suppressed the GABAB receptor‐mediated hyperpolarization, and the effect of TPA was antagonized by sphingosine. Thus, activation of protein kinase C inhibits the expressed GABAB receptor‐mediated response.

Effects of dual-tasking on control of trunk movement during gait: respective effect of manual- and cognitive-task.

Trunk control during gait provides a stable platform for vision and head control. However, in dual-task gait, cognitive tasks result in increased trunk movements, reduced gait speed, and increased gait variability. Manual tasks have been associated with reduced gait speed, but their effects on trunk movement have not been fully investigated. Furthermore, the fear of falling (FoF) during dual-task gait remains relatively unstudied. We aimed to assess trunk movements during cognitive-task gait (CG) and manual-task gait (MG), and examine the effects of CG and MG on individuals with and without FoF. The participants were 117 healthy older adults. We used two triaxial accelerometers: one to record trunk movements at the L3 spinous process and one at the heel to measure initial contact. Participants counted backward by one (CG) or carried a ball on a tray (MG), and we calculated stride time variability and standardized root-mean-square trunk accelerations in the mediolateral (ML) and anteroposterior (AP) directions. CG significantly increased lower trunk oscillations in the ML (t=4.9, p<0.001) and AP directions (t=6.1, p<0.001). Conversely, MG significantly decreased trunk oscillations in the ML (t=-5.9, p<0.001) and AP directions (t=-8.3, p<0.001). The difference in trunk oscillations during CG in the ML direction was significantly larger in subjects with FoF than without FoF (t=2.6, p<0.01). We conclude that for the tasks we studied, CG and MG have different effects on trunk movement. Finally, FoF was associated with changes in trunk movement in the ML direction during CG but not MG.

Expression of the GABAB Receptor in Xenopus Oocytes and Desensitization by Activation of Protein Kinase C

The γ-aminobutyric acid (GABA) receptors have been classified into two subtypes, termed GABAA and GABAB receptors, in the basis of their pharmacological properties (Bowery et al., 1984; 1989; Bormann, 1988). The GABAA receptor with its integrated Cl-channel is now well characterized. Studies revealed the amino acid sequence of the GABAA receptor (Schofield et al., 1987; Levitan et al., 1988). Stimulation of the GABAB receptor has been shown to induce two membrane effects, namely reduction in Ca2+ conductance and increase in K+ conductance (Bormann, 1988; Bowery, 1989), however, the GABAB receptor has not been purified. The expression of GABAB receptor in the Xenopus oocytes may provide information on molecular mechanisms of GABAB receptor-mediated responses.

Novel effect of azide on sodium channel of Xenopus oocytes.

Bath application of a few mM of sodium azide to a voltage clamped oocyte activated a voltage dependent Na+ current. Characteristics of the azide-induced current were the same as those of already described Na+ current induced by prolonged depolarization. The Na+ current induced either by azide or depolarization was suppressed by the application of Ca2+ channel blockers (Diltiazem and La3+). Azide is known to affect some metabolic processes (ATP and cGMP production etc.), but the present effect could not be attributed to metabolic actions.

Enhancement of visual cell response after illumination in the isolated frog retina

Abstract The PIII response of the dark-adapted bullfrog retina increases in amplitude temporarily after exposure to a prolonged weak-adapting light; the magnitude of the enhancement varies with the duration and intensity of the adapting light. The enhancement of the response after illumination is accompanied by a slow positive off-response induced by the adapting exposure so that the vitreal side of the retina becomes transiently positive with respect to the scleral side. A reduction of the Ca 2+ concentration in the extracellular fluid causes the enhanced light-evoked PIII response and the slow positive off-response to be more marked and show a more rapid decay than in the control fluid. These findings suggest that the enhancement of the PIII response and the development of the slow positive off-response after illumination are due to a transient increase of the dark current associated with the rod photoreceptors.

Probabilistic models of state estimation predict visuomotor transformations during prism adaptation.

This study aims to create a prediction model for state-space estimation and to elucidate the required information processing for identifying an external space in prism adaptation. Subjects were 57 healthy students. The subjects were instructed to rapidly perform reaching movements to one of the randomly illuminating light-emitting diode lights. Their movements were measured while wearing prism glasses and after removing that. We provided the following four conditions and control. In target condition, reaching error distance was visually fed back to the subject. In trajectory condition, the trajectory of fingertip movement could be seen, and the final reaching error was not fed back. Two restricted visual feedback conditions were prepared based on a different presentation timing (on-time and late-time conditions). We set up a linear parametric model and an estimation model using Kalman filtering. The goodness of fit between the estimated and observed values in each model was examined using Akaike information criterion (AIC). AIC would be one way to evaluate two models with different number of parameters. In the control, the value of AIC was 179.0 and 154.0 for the linear model and Kalman filtering, respectively, while these values were 173.6 and 161.1 for the target condition, 202.8 and 159.7 for the trajectory condition, 192.7 and 180.8 for the on-time condition, and 206.9 and 174.0 for the late-time condition. Kalman gain in the control was 0.07-0.26. Kalman gain relies on the prior estimation distribution when its value is below 0.5. Kalman gain in the trajectory and late-time conditions was 0.03-0.60 and 0.08-0.95, respectively. The Kalman filter, a state estimation model based on Bayesian theory, expressed the dynamics of the internal model under uncertain feedback information better than the linear parametric model. The probabilistic estimation model can clearly simulate state estimation according to the reliability of the visual feedback.

Activation of type I cyclic AMP-dependent protein kinases is impaired by a point mutation in cyclic AMP binding sites.

The type I regulatory (R-I) subunit of cyclic AMP-dependent protein kinase (A-kinase) was expressed in E. coli, and a single amino acid substitution in cyclic AMP binding sites A or B was introduced by site-directed mutagenesis. The cyclic AMP binding activity and cyclic AMP-stimulated phosphotransferase activity of the holoenzymes formed by wild-type or mutant R-Is and the purified bovine catalytic subunit of A-kinase were then examined. The wild-type holoenzyme was activated by low concentrations of cyclic AMP, a finding in accord with its high-affinity binding to cyclic AMP. In contrast, although the two mutant holoenzymes showed high-affinity cyclic AMP binding at their non-mutated sites, both holoenzymes were resistant to activation by cyclic AMP. Thus, binding of cyclic AMP to the non-mutated cyclic AMP binding site is not sufficient to dissociate the catalytic subunit from the mutant R-Is upon cyclic AMP binding. These results suggest that both A and B cyclic AMP binding sites are required for efficient coupling between cyclic AMP binding and activation of the enzyme.

Characteristics of physical activity in patients with critical limb ischemia

[Purpose] The purpose of this study was to evaluate the amount of physical activity of the patients with critical limb ischemia consecutively in order to clarify the characteristics of physical activity of critical limb ischemia. [Subjects and Methods] Twelve patients who were eligible for the 2 months of consecutive evaluation of the amount of physical activity were enrolled in the study (men: 11; woman: 1; mean age: 64.4 [range: 44–80]). A pedometer with an accelerometer was used for the measurement of the number of steps walked as an index of the amount of physical activity. Participants were asked to lead a regular life and no instruction was given as to the number of steps. [Results] The average number of daily steps walked was 2,323 steps (range: 404–6,505). There was no clear tendency in the number of amputation site-specific steps walked. There was also no correlation between the number of steps walked and age as well as the maximum strength of the knee-extension muscle, skin perfusion pressure of the sole and the dorsum, and QOL scores. [Conclusion] The number of steps walked of the patients with critical limb ischemia was remarkably low and no significant association with health-related QOL.