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Biomedical subjects

A Higashiyama

Publications and source records attributed to A Higashiyama.

At least 19 recordsLinked to original sources
PubMed2001

Coronary vasodilation and positive inotropism by urocortin in the isolated rat heart.

Corticotropin-releasing factor (CRF) has a coronary vasodilator effect and a positive inotropic effect on the isolated rat heart. Recently, expression of CRF receptor type 2 (CRF-R2) has been demonstrated in the heart. In addition, urocortin (Ucn), a new member of the CRF family, has been reported to have much greater affinity for CRF-R2 than CRF. It is suggested that the cardiac effects of Ucn may be more potent than those of CRF. We compared the effect of Ucn with that of CRF on isolated rat heart. The effects of Ucn were then analyzed to determine whether these effects were mediated by CRF receptors and/or any other mediators under the following conditions: perfusion buffer containing (1) alpha-helical CRF 9-41, (2) indomethacin, (3) N(G)-nitro-l -arginine methylester and (4) propranolol. Ucn exhibited a greater effect with a longer duration of action than CRF. Indomethacin significantly attenuated the vasodilator effects of Ucn (P<0.05). CRF receptor antagonist diminished both coronary vasodilation and the positive inotropic effects of Ucn (P<0.05). These results suggest that the cardiac effects of Ucn may be mediated by a CRF receptor, and prostaglandins may be involved in the vasodilator effect.

Analysis of Variance↗
PubMed2000

Characterization of audiogenic-like seizures in naive rats evoked by activation of AMPA and NMDA receptors in the inferior colliculus.

The role of glutamate receptors in the inferior colliculus (IC) in audiogenic and audiogenic-like seizures was investigated in adult rats with transient neonatal hypothyroidism by 0.02% propylthiouracil (PTU) treatment through mother's milk (PTU rats) and in naive rats treated intracisternally with N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole-proprionic acid (AMPA), or cyclothiazide, an inhibitor of rapid AMPA receptor desensitization. All rats showed audiogenic or audiogenic-like seizures characterized by running fit (RF) and generalized tonic-clonic seizures (GTCS). While systemically administered MK-801 inhibited GTCS, intracisternally administered NBQX inhibited RF and GTCS in both audiogenic and audiogenic-like seizures. Auditory stimulation shortened the latency to GTCS induced by AMPA, but not NMDA, at a subclinical dose and further elongated the shortened duration of RF, but not GTCS, induced by MK-801 pretreatment. Furthermore, Northern blot analysis was used to evaluate the expression of the immediate-early gene c-fos in the IC following induction of audiogenic or audiogenic-like seizures. The significant induction of c-fos mRNA by audiogenic seizures in PTU rats or by AMPA- or cyclothiazide-induced seizures in naive rats was prominent in the IC. MK-801 suppressed c-fos mRNA expression in the IC induced by audiogenic seizures in PTU rats or by AMPA-induced seizures in naive rats. NBQX suppressed the expression of c-fos mRNA in the IC induced by AMPA-induced seizures but did not suppress c-fos mRNA in PTU rats or rats with cyclothiazide-induced seizures. Auditory stimuli failed to affect c-fos mRNA induction by AMPA. The present study suggests that audiogenic-like seizures can be reproduced by glutamate receptor agonists in which AMPA receptors are primarily linked to the initiation of audiogenic seizures (RF) while NMDA receptors presumably located within the IC are involved in the propagation of GTCS in audiogenic seizures.

Acoustic Stimulation↗
PubMed2000

Effects of grapefruit juice on the stereoselective disposition of nicardipine in humans: evidence for dominant presystemic elimination at the gut site.

OBJECTIVES: To assess relative roles of the intestinal and hepatic stereoselective metabolism of nicardipine in an oral first-pass disposal with and without grapefruit juice intake. METHODS: The kinetic profiles of (+)- and (-)-nicardipine were studied in the six normal healthy male volunteers who received oral (40 mg) and intravenous (2 mg) racemic nicardipine, first with water and second with grapefruit juice. Both the enantiomers were determined by the stereoselective high-performance liquid chromatographic method, and hemodynamic parameters (arterial blood pressure, heart rate, and electrocardiogram) were assessed when each blood sample was taken. RESULTS: Grapefruit juice compared with water intake caused a significant (P < 0.05) increase in the mean oral (+)- and (-)-nicardipine bioavailability (Fobs) (48.6+/-5.0% and 105.6+/-7.8%) and dose-absorbed (Fabs) available fraction unmetabolized at the gut (Fg) (48.2+/-5.6% and 110.9+/-8.8%, respectively) with no significant change in the hepatic first-pass effect. However, all of the mean kinetic parameters of both the enantiomers after the intravenous dosing of racemic nicardipine did not differ between the grapefruit juice- and water-intake trial phases. The mean percentage changes in oral AUC (43.1+/-3.4% in [+]-nicardipine and 90.9 6.4% in [-]-nicardipine, or Fobs) and Fabs Fg by grapefruit juice tended to be greater for (-)-nicardipine than for (+)-nicardipine and the mean oral (+)/(-)-nicardipine AUC ratio was significantly reduced by grapefruit juice (from 2.25+/-0.37 to 1.75+/-0.28) (P < 0.05). Except for heart rates, which were greater with grapefruit juice (P < 0.05) at 1 and 2 h after the oral dose of nicardipine, the mean hemodynamic variables did not differ between the two trial phases. CONCLUSION: We conclude that the gut is the major presystemic disposal site of racemic nicardipine in humans. Grapefruit juice appears to affect this metabolic disposal of (-)-nicardipine to a somewhat greater extent compared with that of (+)-nicardipine, with an early postdose transient tachycardia after the oral dosing of racemic nicardipine.

Adult↗
PubMed1998

NMDA receptors in the inferior colliculus are critically involved in audiogenic seizures in the adult rats with neonatal hypothyroidism.

The effects of N-methyl-d-aspartate (NMDA) and non-NMDA receptor antagonists were compared on audiogenic seizures in the rats neonatally exposed to propylthiouracil (PTU). The rats treated with 0.02% PTU through mother's milk during days 0-19 after delivery showed a high incidence of audiogenic seizures consisting of running fit (RF) followed by generalized tonic-clonic seizure (GTCS) after matured. The systemic administration with MK-801, a NMDA receptor antagonist dose-dependently inhibited both RF and GTCS. NBQX (6-nitro-7-sulfamoylbenzo[f]quinoxaline-2,3-dione), a non-NMDA receptor antagonist, when systemically administered, failed to block audiogenic seizures. Audiogenic seizures caused a marked induction of c-fos messenger RNA (mRNA) in septal nucleus, bed nucleus of stria terminalis, amygdaloid nuclei, peripeduncular nucleus, and inferior colliculus, which was almost completely blocked by the pretreatment with MK-801. Bilateral microinjection of MK-801 into the inferior colliculus showed a tendency for inhibiting GTCS, but not RF, whereas CPP (3-(R)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid), a competitive NMDA receptor antagonist produced a significant inhibition against both RF and GTCS. These NMDA receptor antagonists administered into cisterna ambience, the floor of which is composed of inferior colliculus and neighboring structures, have shown potent blocking effects on both RF and GTCS. The present results suggest that NMDA receptors in the inferior colliculus, presumably in the subnucleus of external cortex may play the critical role in the initiation of audiogenic seizures in PTU-treated rats.

Acoustic Stimulation↗
PubMed1998

Apparent body tilt and postural aftereffect.

Apparent orientation of the body tilted laterally in the frontal plane was studied with the methods of absolute judgments in four experiments. In Experiment 1, 17 subjects, who maintained the normal adaptation of body to gravity, estimated their body tilts under the condition of seeing the gravitational vertical and under the condition of eliminating it. The results showed that (1) there was not a significant difference between the two conditions and (2) the small tilts of less than 45 degrees were exactly estimated, whereas the large tilts of 45 degrees-108 degrees were overestimated. In Experiment 2, 10 subjects estimated their body tilts under three velocities of a rotating chair on which each subject was placed. Although both body tilt and chair velocity were found to influence tilt estimation, the effect of body tilt was overwhelmingly greater than that of chair velocity. In Experiment 3, 11 subjects adapted their bodies to a 72 degrees left tilt for 10 min and then estimated various body tilts around the adapting tilt. The estimations obtained under the 72 degrees adaptation were lower than those obtained under the 0 degree adaptation, and this reduction was greater for the test tilt that was farther away from the adapting tilt. In Experiment 4, 11 subjects adjusted their own body tilts to designated angles. The results confirmed the outcomes of absolute estimation in Experiments 1-3. From these findings and past literature, the judgments of body tilt were considered to be subserved by a single sensory process that was based on the cutaneous and muscular proprioceptors, rather than the vestibular and joint proprioceptors.

Adult↗
PubMed1998

Estimation of height for persons in pictures.

We report three experiments in which subjects estimated the height of persons seen in pictures. In Experiment 1, 50 realistic photographs were used as targets. The correlation between mean estimated height and actual height was .92, and target's sex and the ratios of head to trunk, which included horizontal ratio (i.e., a ratio of head width to shoulder width) and vertical ratio (i.e., a ratio of head height to stature), were found to be effective on height estimates, although target's sex was more effective than ratios of head to trunk. In Experiments 2 and 3, the recognizability of target persons was reduced, respectively, by inverting the person photographs and by degrading the various features of the photographs. The main results were that (1) the correlation between mean estimated height and actual height was .88 for the inverted photographs and was .80, on average, for the degraded drawings; (2) target's sex was consistently influential in both experiments; (3) vertical ratio was effective for the inverted photographs and the mildly degraded drawings but not for the extremely degraded drawings in which only outlines of target persons were depicted; and (4) the estimation for the outlined pictures was likely to be influenced by fit of clothes to targets' bodies. From these findings, person stimuli were considered to provide a stable metric stick of visual space under naturalistic circumstances.

Adolescent↗
PubMed1998

[Running fit and generalized tonic-clonic seizure are differently controlled by different subtype receptors in the brainstem].

Rats neonatally treated with 0.02% propylthiouracil (PTU) through mother's milk showed a high incidence of audiogenic seizures after maturation. These audiogenic seizures were differently modified by MK-801 and NBQX; while intraperitoneal MK-801 equally inhibited running fit (RF) and generalized tonic-clonic seizure (GTCS), NBQX administered into cisterna ambiens significantly inhibited RF but not GTCS. The possible involvement of glutamate receptors in the inferior colliculus was further investigated using naive Sprague-Dawley rats injected with NMDA, AMPA or cyclothiazide, known as an inhibitor of desensitization of AMPA action. All drugs tested successfully induced RF followed by GTCS, resembling audiogenic seizures in PTU-treated rats. However, sound stimulation could augment AMPA-induced, but not NMDA-induced GTCS. Systemic administration with MK-801 potently blocked GTCS induced by AMPA/cyclothiazide, but the same drug failed to block RF after intracisternal injection with AMPA/cyclothiazide. Furthermore, intracisternal administration with NBQX significantly inhibited only RF induced by AMPA/cyclothiazide. The present study suggests that: 1) glutamate receptors in the brainstem, possible in the inferior colliculus, play a crucial role in audiogenic seizures, namely the initiation of RF and propagation into GTCS; and 2) the initiation mechanism is regulated by both NMDA and AMPA receptors, whereas propagation is mainly controlled by NMDA receptors.

Acoustic Stimulation↗
PubMed1997

Altered expression of troponin T isoforms in mild left ventricular hypertrophy in the rabbit.

Alterations in troponin T (TnT) isoforms have been reported in severe human and experimental heart failure (HF), and may play a role in the depressed myofibrillar ATPase activity observed in this condition. It is unclear whether these alterations reflect very severe hemodynamic derangement or are a component of mild hypertrophic stress. Therefore, we studied the expression of TnT isoforms (SDS-PAGE, Western blots), myosin isoforms, myofibrillar ATPase activity, and left ventricular (LV) mechanoenergetics (rbc perfused, isovolumically contracting isolated heart) in a rabbit model of mild hypertrophy (LVH) due to gradual hypertension caused by 12 weeks of cellophane wrap of the kidneys (n=12). LV/body weight ratio increased by 28% in LVH compared to shams (P<0.001); no animals had evidence of HF. In LVH, the percentage of TnT2 was modestly but significantly increased compared to shams [6.2+/-1.9 (+/-S.D. ) v 3.7+/-1.0%, P<0.05], mainly as a consequence of a parallel decrease in TnT4 (P=0.07). Sham hearts ranged from 75-100% V3 isomyosin, whereas all LVH hearts had 100% of the V3 form. There were no significant differences in myofibrillar ATPase activity or mechanical variables, including contraction and relaxation rates. The slope of the VO2-pressure-volume-area relation (a measure of the energy conversion efficiency of the contractile machinery) was also unchanged. We conclude that in the rabbit, shifts in TnT isoforms toward a more "fetal" pattern occur during mild LVH and, therefore, are likely to be a general feature of the response to hemodynamic stress, rather than a phenomenon confined to end-stage disease. These modest shifts are not associated with major alterations in LV myofibrillar ATPase activity or mechanoenergetics.

Adenosine Triphosphatases↗
PubMed1997

Estimation of nonmechanical VO2 in isolated rabbit heart: comparison of mechanical unloading and BDM method.

To understand the mechaneoenergetics of heart muscle, it is important to be able to accurately partition energy consumption into its two major components, that used for nonmechanical activity [mainly excitation-contraction (E-C) coupling and basal metabolism] and that used for mechanical activity (cross-bridge cycling). In most experiments in the beating heart, this has been accomplished by assuming that the unloaded oxygen consumption (VO2) represents nonmechanical VO2 and subtracting it from total VO2 to yield mechanical VO2. However, unloaded VO2 is "contaminated" by an uncertain amount of energy consumption for cross-bridge cycling under unloaded conditions. We recently, reported an alternative method to estimate nonmechanical VO2 using the negative inotropic drug 2,3-butanedione monoxime (BDM), which, in theory, should not include cross-bridge cycling-related energy consumption. In the present study, we compared changes in unloaded VO2 and the BDM estimate of nonmechanical VO2 as E-C coupling was varied by changing the perfusate Ca2+ concentration ([Ca2+]) in the isolated rabbit heart. An isolated, red blood cell-perfused, isovolumically contracting balloon in left ventricle preparation was employed. In one group (n = 8), contractility (maximal elastance), unloaded VO2, and the BDM estimate of nonmechanical VO2 were assessed at a perfusate [Ca2+] of 2.5 mM and then at 5.0 mM. In a second group (n = 6), perfusate was 1.0 and 2.5 mM. The change in contractility in each group as [Ca2+] was increased was comparable. Unloaded VO2 was systematically greater than the BDM estimate of nonmechanical VO2 under all conditions. However, the absolute change in both estimates was similar in both groups. In conclusion, over the range of perfusate [Ca2+] employed in this study, changes in unloaded VO2 and the BDM estimate of nonmechanical VO2 are similar. These results support the use of unloaded VO2, which is easier to measure and has less estimation error in individual cases than the BDM-derived value for nonmechanical VO2, as an accurate index of change in E-C coupling energy consumption.

Animals↗
PubMed1996

Rapid shortening during relaxation increases activation and improves systolic performance.

BACKGROUND: Previous studies in cardiac muscle and isolated heart preparations generally have attributed positive effects of ejection to greater length-dependent activation. However, there have been some reports of an ejection-related increase in contractile function that is independent of end-diastolic volume (EDV) history. The present study was designed to more fully characterize the mechanoenergetic results of the latter effect in the intact ventricle. METHODS AND RESULTS: A servomotor was used to initiate left ventricular volume reduction (VR) at end systole, with EDV kept constant. Seven isolated, red blood cell-perfused rabbit hearts were studied at constant EDV during isovolumic contraction, slow VR (5.0 +/- 0.9 EDV/s), and rapid VR (26.8 +/- 5.1 EDV/s). Compared with isovolumic beats, VR caused an enhancement in contractility. This effect was greater for rapid VR and required > 50 beats to attain steady state. Rapid VR increased developed pressure by 15% (92.2 +/- 23.7 [mean +/- SD] versus 105.9 +/- 27.6 mm Hg), maximum dP/dt by 17% (1223 +/- 401 versus 1435 +/- 505 mm Hg.s-1), and Emax (slope of the end-systolic pressure-volume relation) by 13% (69.4 +/- 19.9 versus 78.6 +/- 23.0 mm Hg/mL) (all P < .01). Left ventricular oxygen consumption (VO2) was unchanged with slow VR and decreased by 8% with rapid VR (0.0744 +/- 0.0194 versus 0.0683 +/- 0.0141 mL O2.beat-1.100 g-1; P < .05). In separate hearts (n = 8), costs (basal metabolism and excitation-contraction coupling) were estimated by use of 2,3-butanedione monoxime. Compared with control, rapid VR was associated with a 26% increase in nonmechanical VO2 (0.0248 +/- 0.0021 versus 0.0312 +/- 0.0022 mL O2.beat-1.100 g-1; P < .01), consistent with an increase in calcium cycled per beat. CONCLUSIONS: Ejection after end systole has a positive effect on ventricular performance that cannot be ascribed to length-dependent activation and is likely related to an increase in calcium available for activation. Similarly, an increase in nonmechanical VO2 associated with ejection suggests a positive interaction between myofilament shortening and activator calcium cycling.

Animals↗
PubMed1996

Involvement of tumor necrosis factor alpha and very late activation antigen 4/vascular cell adhesion molecule 1 interaction in surgical-stress-enhanced experimental metastasis.

We examined the influence of surgical stress on hematogenous metastasis of malignant tumor cells. The study was performed by focusing on the involvement of inflammatory cytokines in the serum, raised acutely after surgery, and endothelial adhesion molecules in the metastatic process. Surgical stress, given to C57BL/6 mice before B16-BL6 melanoma inoculation, significantly enhanced the pulmonary metastasis. This enhancement was seen when the surgery lasted for more than 2 h. After the 2-h surgery, the enhancement of pulmonary metastasis was seen most remarkably when B16-BL6 was inoculated 24 h after surgery. The serum level of tumor necrosis factor alpha (TNF alpha) in the mice that underwent the 2-h surgery peaked 12 h after the surgery. In contrast, serum interferon gamma was not detectable. Administration of an anti-TNF alpha mAb before the surgery inhibited the enhanced metastasis by inhibiting the increased expression of vascular cell adhesion molecule 1 (VCAM-1) on lung vascular endothelium after the surgery. Pretreatment of B16-BL6 cells with an anti-very late activation antigen 4 (anti-VLA-4) mAb completely inhibited the enhanced metastasis after surgery. Administration of an anti-VCAM-1 mAb before surgery also inhibited the enhancement. These results indicate that serum TNF alpha, raised by surgical stress, is critically involved in the enhanced pulmonary metastasis of mouse melanoma by inducing VCAM-1 expression on lung vascular endothelium.

Animals↗
PubMed1996

Restoring forces assessed with left atrial pressure clamps.

A negative pressure (P) in the fully relaxed left ventricle (LV) indicates the presence of restoring forces generated during contraction. To assess restoring forces in the intact LV under physiological filling conditions, a servomotor system was used in anesthetized open-chest dogs (n = 8) to produce nonfilling diastoles by left atrial pressure (LAP) clamping during systole such that LAP was less than left ventricular pressure (LVP) during the subsequent diastole. Steady-state LV end-diastolic pressure (EDP) was varied by volume infusion from 4.0 +/- 1.5 (+/-SD) to 12.8 +/- 2.1 mmHg. The corresponding fully relaxed LVPs increased from -2.1 +/- 1.9 to 1.1 +/- 3.2 mmHg, P < 0.001. LAP clamping increased the rate of LVP fall by 34 +/- 28% (P < 0.001) during 10 ms after the LVP dropped below the level of the LVP-LAP crossover of the preceding normal beat. During clamped beats, two-dimensional echo revealed substantial downward displacement of the mitral valve (MV) leaflets despite the reversed LA-LV gradient and absence of filling. Thus 1) restoring forces are present at low physiological EDP but absent at high physiological EDP; 2) filling retards the rate of fall of LVP; 3) even in the absence of filling, the process of LV relaxation facilitates MV opening.

Animals↗
PubMed1996

Horizontal and vertical distance perception: the discorded-orientation theory.

We sought the conditions where the horizontal-vertical illusion (HVI) takes place outdoors in an open field. Longitudinal distance from a subject to a building wall was adjusted to appear equal to the vertical or horizontal distance on the wall. To examine validity of previous theories (physiology, frame, depth, and gravity theories), boundary of visual field (ellipse and circle), bodily orientation (upright and lying), and orientation of visual objects (normal, 90 degrees-tilted, and inverse) were manipulated in eight experiments. These three independent variables affected the HVI effects, but their effects were not explained by the previous theories. We therefore proposed a model on the basis of discord among the retinal, visual, and gravitational orientations. We also found that longitudinal distance was adjusted as being consistently larger than the standard distance. This result was explained by the reduction of cues to distance and the HVI effect.

Attention↗
PubMed1994

Preload does not influence nonmechanical O2 consumption in isolated rabbit heart.

Myocardial energy consumption for nonmechanical activity (excitation-contraction coupling) has been shown to be length dependent in isolated muscle studies but no more than minimally affected by preload in the whole heart. However, unloaded O2 consumption (VO2, which is used to estimate nonmechanical VO2 in whole heart) may not be accurate for quantifying nonmechanical energy consumption, because it contains VO2 for residual cross-bridge cycling. To more accurately determine the influence of left ventricular (LV) diastolic volume on nonmechanical VO2 in whole heart, we employed a new method for quantifying nonmechanical VO2, using the drug 2,3-butanedione monoxime (BDM). We measured VO2 and force-time integral during infusion of BDM (< or = 5 mM) at high (VH) and low LV volumes (VL) in 16 excised isovolumically contracting red blood cell-perfused rabbit ventricles. LV end-diastolic pressure was 9.7 +/- 4.6 and 3.8 +/- 2.8 (SD) mmHg at VH and VL, respectively. Nonmechanical VO2, estimated as the VO2-axis intercept of the linear VO2-force-time integral relation obtained during BDM infusion, did not differ significantly between VH and VL (0.0137 +/- 0.0083 and 0.0132 +/- 0.0090 ml O2.beat-1 x 100 gLV-1, P = 0.702). A multiple linear regression analysis for the pooled data confirmed this finding (P = 0.361). We conclude that, in the rabbit heart, LV diastolic volume does not importantly affect nonmechanical energy consumption over a physiological range of LV end-diastolic pressure. This indicates that length-dependent activation does not have an energetic cost in whole rabbit heart and suggests that its predominant mechanism is increased Ca2+ affinity for the contractile proteins.

Animals↗
PubMed1994

How accurate is size and distance perception for very far terrestrial objects? Function and causality.

This study investigated absolute estimation of size and distance for natural and artificial objects at viewing distances of 1.1-15.3 km (Experiments 1 and 2) and 0.4-5.0 m (Experiment 3). The main results were that, regardless of distance range, size and distance estimates (S' and D') were related to objective size and distance (S and D), respectively, by a power function with an exponent of unity, but great individual differences in exponent were obtained for the far objects. The ratio S'/D' was reasonably represented by S'/D' = K theta n and S'/D' = tan(a theta +b), rather than S'/D' = tan theta, where theta is the visual angle. Partial correlations were obtained to examine whether (1) apparent size is determined by taking apparent distance into account or (2) both apparent size and apparent distance are determined directly by external stimuli. The combined data for the far objects and the data for the close objects showed that there were high correlations between S and S' and between D and D' and a low correlation between D' and S'. The data of Experiment 2 showed that both D' and S' were highly correlated with S, D, and theta, and there was a high positive correlation between D' and S'. It was suggested that the direct-perception model is valid under some situations, but the taking-into-account model is not supported in any set of data.

Distance Perception↗
PubMed1993

Electrocutaneous spatial integration at suprathreshold levels: an additive neural model.

The effect of cathode size on estimates of the magnitude of electrocutaneous stimulation were studied. The 24 Ss made magnitude estimates for combinations of 6 cathode sizes (2.5-30 mm diameter) and 5 currents (1.5-3.3 times the threshold). Estimates for small cathodes were consistently smaller but grew more rapidly than those for intermediate and large cathodes. From the results, contours were constructed showing how area and current trade off to maintain apparent intensity. These area-current contours suggest that supersummation prevails at low estimation levels and complete summation tasks place at high levels. An additive neural model is proposed to account for the results and is also applied to other somatosensory systems.

Adolescent↗
PubMed1993

Localization of electrocutaneous stimuli on the fingers and forearm: effects of electrode configuration and body axis.

Four experiments were done on the effects of electrode configuration (concentric vs. unifocal) and body axis (longitudinal vs. transverse) on localization of electrocutaneous pulse stimuli at the fingers and forearm. Subjects pointed to the apparent location of current pulses. For the transverse placement of electrodes, pulses were localized correctly, whatever the configuration and the body site might be. In addition, intrasubject variability at the forearm was smaller for the transverse axis than for the longitudinal axis. For the longitudinal placement of electrodes, pulses were localized as a function of configuration and body site. At the fingers, concentric electrodes provided precise localization but unifocal electrodes provided a great mislocalization; and intrasubject variability of localization was larger for the unifocal electrodes than for the concentric electrodes. At the forearm, whatever the configuration might be, the pulses were localized more proximally than the stimulus site; and intrasubject variability of localization did not differ between the configurations. These results are related to Boring's anchor theory, apparent distance between two points, and the localization of other somatosensory stimuli.

Adult↗