Hideo Eda

Cortical mapping of gait in humans: a near-infrared spectroscopic topography study.

While we have a fair understanding of how and where forelimb-hand manipulative movements are controlled by the neocortex, due to functional imaging studies, we know little about the control of bipedal movements such as walking because of technical difficulties. We succeeded in visualizing cortical activation patterns of human gait by measuring relative changes in local hemoglobin oxygenation using a recently developed near-infrared spectroscopic (NIRS) topography technique. Walking activities were bilaterally associated with increased levels of oxygenated and total hemoglobin in the medial primary sensorimotor cortices and the supplementary motor areas. Alternating foot movements activated similar but less broad regions. Gait imagery increased activities caudally located in the supplementary motor areas. These findings provide new insight into cortical control of human locomotion. NIRS topography might be also useful for evaluating cerebral activation patterns during pathological gait and rehabilitative intervention.

Premotor cortex is involved in restoration of gait in stroke

Cortical activation during hemiplegic gait was assessed in six nonambulatory patients with severe stroke (four men, two women; four with right and two with left hemiplegia; 57 years old and 3 months after stroke on average), using a near‐infrared spectroscopic imaging system. Each patient performed tasks of treadmill walking (0.2km/hr), alternated with rest every 30 seconds for four repetitions, under partial body weight support, either with mechanical assistance in swinging the paretic leg control (CON) or with a facilitation technique that enhanced swinging of the paretic leg (FT), provided by physical therapists. Gait performance was associated with increased oxygenated hemoglobin levels in the medial primary sensorimotor cortex in the unaffected hemisphere greater than in the affected hemisphere. Both cortical mappings and quantitative data showed that the premotor activation in the affected hemisphere was enhanced during hemiplegic gait. There was also a prominent activation in the presupplementary motor area. Overall cortical activations and gait performance were greater in walking with FT than with CON. These indicate that multiple motor areas including the premotor cortex and presupplementary motor area might play important roles in restoration of gait in patients with severe stroke.

Circulatory basis of fMRI signals: relationship between changes in the hemodynamic parameters and BOLD signal intensity.

Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) is widely used as a tool for functional brain mapping. During brain activation, increases in the regional blood flow lead to an increase in blood oxygenation and a decrease in paramagnetic deoxygenated hemoglobin (deoxy-Hb), causing an increase in the MR signal intensity at the site of brain activation. However, not a few studies using fMRI have failed to detect activation of areas that ought to have been activated. We assigned BOLD-positive (an increase in the signal intensity), BOLD-negative (a decrease in the signal intensity), and BOLD-silent (no change) brain activation to respective circulatory conditions through a description of fMRI signals as a function of the concentration of oxygenated Hb (oxy-Hb) and deoxy-Hb obtained with near-infrared optical imaging (NIOI). Using this model, we explain the sensory motor paradox in terms of BOLD-positive, BOLD-negative, and BOLD-silent brain activation.

Characterization of homogeneous tissue phantoms for performance tests in diffuse optics

Solid homogeneous turbid phantoms can be employed to mimic the attenuation and angular distribution of light emerging from tissue, e.g., to assess the responsivity of the detection system of diffuse optics instrumentation and to support standardized performance tests of functional near-infrared spectroscopy devices. We present three methods to quantify the wavelength-dependent diffuse transmittance, relying on (1) measurement of radiance exiting the phantom by a detector far from the exit aperture, (2) simple recording of radiance by a power meter close to the exit aperture and correction for the finite distance between phantom surface and detector, (3) determination of the reduced scattering and absorption coefficients by time-resolved diffuse transmittance measurements and forward calculation of the time-integrated diffuse transmittance based on the diffusion model. The implications of the different approximations related to these approaches are discussed. The various methods were applied to characterize solid slab phantoms, and the results were compared. Specifically, for an epoxy-resin based phantom having a thickness of 2 cm, a reduced scattering coefficient of about 0.5/mm and an absorption coefficient of about 0.01/mm, the diffuse transmittance values obtained by the three different methods were found to agree within about 10%.

Visualization of children's mathematics solving process using near infrared spectroscopic approach

Over the past decade, the application of results from brain science research to education research has been a controversial topic. A NIRS imaging system shows images of Hb parameters in the brain. Measurements using NIRS are safe, easy and the equipment is portable, allowing subjects to tolerate longer research periods. The purpose of this research is to examine the characteristics of Hb using NIRS at the moment of understanding. We measured Hb in the prefrontal cortex of children while they were solving mathematical problems (tangram puzzles). As a result of the experiment, we were able to classify the children into three groups based on their solution methods. Hb continually increased in a group which could not develop a problem solving strategy for the tangram puzzles. Hb declined steadily for a group which was able to develop a strategy for the tangram puzzles. Hb was steady for a certain group that had already developed a strategy before solving the problems. Our experiments showed that the brain data from NIRS enables the visualization of childrens mathematical solution processes.

NIRS evaluates the thinking process of Mushi-kuizan task

We discuss the possibility of Near Infrared Spectroscopy (NIRS) application to the educational research. NIRS system was used for prefrontal cortex measurement of children, when they were solving Mushi-kuizan problems. The Mushi-kuizan task is one of the mathematical puzzles. Subjects were four children in fifth grade. Hemoglobin parameters such as oxygenated hemoglobin and deoxygenated hemoglobin were calculated during Mushi-kuizan problems. The parameters were compared with the performance data of each subject. Changes Hb parameters described how children use their brain. NIRS evaluated the thinking process of mathematics task. It is very useful for mathematics teachers to catch the childrens thinking process dynamically because they can consider the way of teaching for each child. It was shown that NIRS may be able to apply to education.

Near-infrared spectroscopy with Spectroscopic technique with wide range of wavelength information detects tissue oxygenation level clearly

Near-infrared spectroscopy (NIRS) is based on the modified-Lambert-Beers law that changes in absorbance are proportional to changes in hemoglobin parameters. Majority of the conventional measurement methods uses only two or three wavelengths. In this research, basic examination of NIRS measurement was approached by acquiring wide range of wavelength information. Arterial occlusion task was performed by using the blood pressure cuff around the upper arm. Pressure of 200mmHg was then applied for about 3 minutes. During the arterial occlusion, the spectrum of the lower arm muscles was measured every 15 seconds, within the range of 600 to 1100nm. The secondary derivative spectrum was calculated from the measured spectrum. Arterial occlusion is a task which changes the oxygenation level of the tissue. The change can be regarded as the change of the spectrum form, not as the change of the baseline. Furthermore, it was found that other wavelength bands hold information correlating to this arterial occlusion task.

Measurement of brain activation difference during different mathematical tasks by near infrared spectroscopy

This study examines differences in concentration changes of hemoglobin in the brain while finding algebraic solutions versus geometrical solutions. We use Near Infrared Spectroscopy imaging system to measure the hemoglobin changes while subjects are solving algebraic task and geometrical task. NIRS imaging system can measure changes in the concentration of hemoglobin. This brain activity data shows a difference between the two different experimental tasks which helps us to identify the characteristics of thinking processes.

Spectroscopic technique with wide range of wavelength information improves near-infrared spectroscopy

Near-infrared spectroscopy (NIRS) calculates hemoglobin parameters, such as oxygenated hemoglobin (oxyHb) and deoxygenated hemoglobin (deoxyHb) using the near-infrared light around the wavelength of 800nm. This is based on the modified-Lambert-Beers law that changes in absorbance are proportional to changes in hemoglobin parameters. Many conventional measurement methods uses only a few wavelengths, however, in this research, basic examination of NIRS measurement was approached by acquiring wide range of wavelength information. Venous occlusion test was performed by using the blood pressure cuff around the upper arm. Pressure of 100mmHg was then applied for about 3 minutes. During the venous occlusion, the spectrum of the lower arm muscles was measured every 15 seconds, within the range of 600 to 1100nm. It was found that other wavelength bands hold information correlating to this venous occlusion task. Technique of improving the performance of NIRS measurement using the Spectroscopic Method is very important for Brain science.

Development of Laser Cell-Chip System for Cell Functional Analysis

Abstract A new type of cell-cultivation system based on laser processing has been developed for the on-chip cultivation of living cells. Here we introduce a “laser cell-chip“. A sheet prepared from epoxy resin was processed by KrF excimer laser (248 nm, 1.6 J/cm2) for preparation of microgrooved surfaces. A laser cell-chip can make kinetic studies of cell migration depending on the concentration gradient of a chemoattractant. In this study, megakaryocytes were used for the migration on a groove of laser cell-chip by the concentration gradient of the stromal cell derived factor 1 (SDF-1/CXCL12). SDF-1/CXCL12 plays an important and unique role in the regulation of stem/progenitor cell trafficking. A megakaryocyte was migrated on a groove of laser cell-chip depending on the optical concentration gradient of SDF-1/CXCL12. However, SDF-1-induced cell migration was inhibited by the pretreatment of phosphatidylinositol 3-kinase (PI3K) inhibitor, wortmannin or LY294002, suggesting that PI3K is likely involved in ...