It gradually becomes clear that aortic walls are more compliant in the ventral side than the dorsal. This indicates that cyclic deformation of aortic wall is higher in the ventral side during heart beat, which may cause difference in the properties of smooth muscle cells (SMCs). In this study, we observed the dorsal-ventral (DV) difference in the contractility and RNA expression levels in rabbit thoracic aortas. Aortic walls were more contractile in the ventral side than the dorsal not only in tissue level but also in cellular level. Microarray analysis showed several genes with DV difference, including osteopontin with higher expression in the dorsal side and actin with higher expression in the ventral. Osteopontin stimulates DNA synthesis in SMCs and actin is one of the most important contractile proteins. Thus, SMCs in the dorsal side may have more synthetic phenotype and those in the ventral side more contractile.
The heart has a dynamic compensatory mechanism for haemodynamic stress. However, the molecular details of myocardial mechanotransduction have remained unclear. Previously, we reported that recombinant TRP vanilloid family type 2 channels (TRPV2) can be activated by hypotonicity- and stretch-induced mechanical stimulation in ectopic expression systems. Interestingly, TRPV2 is highly localized to mammalian cardiac intercalated discs. To elucidate the physiological role of cardiac TRPV2, we generated temporally-controlled cardiac-specific TRPV2-deficient mice. The elimination of TRPV2 in the mouse heart resulted in an immediate severe decline in cardiac function, with disorganization of the intercalated discs that support mechanical coupling with neighbouring myocytes, which triggered abnormal cell shortening and Ca2+ handling, and myocardial conduction defects. TRPV2-deficient hearts showed down-regulation of the IGF-1 receptor/PI3K/Akt signalling pathway and no compensatory hypertrophic responses to mechanical overload. These results provide a molecular basis for maintaining cardiac structure and function in response to haemodynamic stress.
Angiogenesis, the formation of new blood vessels from pre-existing vasculature, regulates various physiological and pathophysiological processes. Here, we investigated the molecular mechanisms of angiogenesis by performing fluorescence-based bio-imaging analyses using zebrafish as a model animal and showed the potential role of intravascular pressure in regulation of angiogenesis. In severed blood vessels, the vessels located downstream of blood flow preferentially elongate to reconnect the damaged vessels comparing to the upstream vessels. Endothelial cell migration and proliferation actively occurred mainly in the downstream vessels. Since it is assumed that intravascular pressure is higher in the upstream vessels than in the downstream ones, these results suggest that intravascular pressure might regulate angiogenesis. Consistently, our preliminary in vitro data suggested that increased hydrostatic pressure inhibited vessel elongation in a 3D microfluidic angiogenesis model. These results suggest that hydrostatic pressure inhibits vessel elongation during angiogenesis by suppressing endothelial cell migration and proliferation.
Vascular endothelial cells (ECs) respond to the hemodynamic forces shear stress and stretch by altering their morphology, functions, and gene expression. Here we report that plasma membranes differentiate between stretch and shear stress by undergoing transitions in its lipid phases. Shear stress decreased the lipid order of EC plasma membranes; uniaxial stretching and hypotonic swelling increased the membrane lipid order. Similar changes in lipid order occurred in the artificial lipid bilayer membranes of giant unilamellar vesicles, indicating that these are physical phenomena. Blocking these changes in the membrane lipid order by depleting membrane cholesterol with methyl-β-cyclodextrin or by adding cholesterol resulted in marked inhibitions of the stretch or shear stress induced phosphorylation of PDGF receptors or VEGF receptors, respectively. These results indicate that EC membranes differently respond to hemodynamic forces and that the changes in membrane physical properties are involved in the mechanotransduction that activates membrane receptors to each force.
In elder-dominated society, there are a lot of social problem such as the lack of labor. Robotics technology is paid attention to solve these kinds of problems. In this presentation, development and business using robotics technology for the agriculture, manufacturing and service filed are introduced. Especially, the projects based on the collaboration between medical and engineering technology are focused.
As the risk of falling is a important matter to prevate for the elderly comeing to a day service, cuntinuous study have been done.Toe gap test(right and left),Time up and go test,Functional reach test was picked up as a checking parameter for the prevation against falling. This time,physical frailty and the risk of falling is studied.The subjects are 22 who use our day services at least one year.They are divided into ones who have not falled during a year and ones who have falled.The center value of each parameter was followings;Toe gap test(right)of non-falling:2.35kg and of falling:1.40kg, Toe gap test(left)of non-falling: 2.19kg and of falling:1.47kg, Time up and go test of non-falling:12.09sec and of falling:17.24 sec, Functional reach test of non-falling:21.26cm and of falling:19.94cm, respectively. Toe gap test and Time up and go test seems to be convinient parameters to prevent against falling risk.
The advance in semiconductor manufacturing technology has been promoting lower prices and higher performance for microprocessors and sensors. Herewith, it is possible to develop low cost bio-measurement equipment and these applications are expanding. Thus, we started to develop the compact electroencephalograph that is easier to use. The downsizing of the electroencephalograph was possible at a low cost by build-up type hardware structure consists of main module, amplifier module and filter function using software. The brain wave signal that is measured at the amplifier board is converted to data at main module. The processed data is sent to the PC or tablet via Wi-Fi. In this paper, we discuss the technology of the developed electroencephalograph and its applications.
There is an important cohort study indicating that frequent performance of music instrument has the significant effect of reducing the risk of dementia in the elderly. We have been developing a novel electronic musical instrument Cymis (Cyber Musical Instrument with Score), showing that persons with neural or motor impairments such as cerebral palsy can play the piece easily. The aim of the present study is to develop a network system enabling the ensemble of the Cymis. Firstly we found that the elderly can play the Cymis easily under support of a music therapist. Secondly, four university students including two female majoring music and two beginners of music were able to perform ensemble with the Cymis, where two beginners watched guide of performance on the monitor. By measuring time differences in performances of four people, it was indicated that beginners also could perform ensemble with slight time differences against others.
The various systems using the information of pupil diameter variation have been studied and developed, e.g. gaze measurement and the estimation of interest. These systems are presupposed to be operated on the PC or portable terminal. To measure the pupil diameter, a near-infrared camera and illumination are required. However, the conventional PC or portable terminal does not have a near-infrared camera and illumination. In this study, for the generalization of the systems using the information of pupil diameter variation, we proposed the measurement method of the pupil diameter from the image taken by a visible-light camera. From the experimental results, the accuracy of proposed method was equivalent to that of the conventional method of pupil diameter using a near-infrared camera and illumination.
(Introduction) We had been measuring the odor in hospital. So the bad odor in hospital is from human. The human odor is consists of many organic substances. So we tried to make a small decompose odor substances apparatus by a titanium oxide which is a photocatalyst.We simulate human odor using alkaline ammonia, acid of the acetic acid and neutral methanol. So we measured in quantitative measurement by odor sensory test and machinary measurement.(Result) By this device is made of 21 pieces of 380 nm LEDs, and fixed fan which flow rate of 16 L/min. The methanol odor is quantitatively mesured by both odor sensory test and machinary. This measurement are exponentially reduce of odorous substances. (Conclusion) The human odor is reduced by our small device using a photochemical reaction, these odor was reduced at 63% within 20 minutes to 25 minutes quantitatively. And this curve was exponential decrease.
The objective of this study is the development of the device gives direction of power for the human. The device made up of 4 stack linear oscillatory actuators on 3 axis. These actuators are mounted on the ball-like metallic frame that is 40 mm diameter. We can feel the direction of power using this device. Displayed angles transform Spherical Polar Coordinates. The microprocessor makes PWM based on Spherical Polar Coordinates. PWM signals drive 12 actuators. In the future, it will be possible to guide the visually-impaired in arbitrary direction.
We are exploring the potential use of photodynamic therapy (PDT) for wound healing. In this study, we examined whether PDT with aminolevulinic acid (ALA) promoted epithelization using a skin defect model mouse (C57/BL6, 8-10w, ♂). Mice were applied with ALA gel (10%, 1%, 0.1% 0.01% and 0.0001%) on the skin lesions and irradiated with a 630 nm light source. Skin defect areas were measured on 0, 1, 3, 5, 7, 10, 12 and 14 days after PDT. Fluorometric analysis revealed that red fluorescence probably due to protoporphyrin IX (PPIX), a metabolite of ALA was seen in the ALA applied region. Epithelization in mice with ALA-PDT was significantly faster than that in control mice and angiogenesis was substantially seen in the healed area. These results suggested that PDT using ALA promoted wound healing.
The time pressure caused under the time constraints induces the human error or misjudgment. The estimation methods of the psychological states using gaze information have been investigated. However, the characteristics of gaze under the condition of the time pressure were not well investigated. We thus investigate the relationship between gaze characteristics and time pressure under the time constraints. In order to induce time pressure, the visual search tasks were presented to subjects. In this study, the degree of time pressure and/or frustration were evaluated by the subjective assessments. We investigated the relationship between the variation of gaze velocity and the time pressure.
The service called "Google Safe Search" has been provided to hide the inappropriate images on web browser. The inappropriate images which cannot be detected by the Google Safe Search are selected by user's report. However, it is difficult to get the information of inappropriate image from inexperienced PC users. If the emotion (pleasant or unpleasant) of users during web browsing can be estimated automatically, it is judged whether the image shown on the web browser is appropriate or not. We thus develop the emotional estimation method which combines the gaze information with the visual saliency. In this paper, we show the relationship between the emotion and the number of visual fixation in the salient region of an image
In laparoscopic liver surgery, laparoscopic ultrasound (LUS) is indispensable to understand inner structure such as vessels and tumors. However, LUS is not convenient due to poor operability, and does not provide positional information in the endoscopic view. To address the issue, we have developed both a robotic hand for LUS and a 3D visualization software. In this study, we describe the software which provide 3D ultrasound by scanning LUS. To confirm the system feasibility, an experiment using a polyurethane liver phantom was conducted. Figure shows the reconstructed volume with vessels. The computational time was approximately 50 msec less than typical imaging period of ultrasound.
We have developed a coherent anti-Stokes Raman scattering (CARS) rigid endoscope for label-free nerve imaging during an operation. The CARS rigid endoscope consists of a single-mode fiber which delivers two color lasers, a galvano scanning system, and homemade ϕ12 mm lens tubes which include two relay lenses and an objective lens. The label-free imaging of rat sciatic nerve is demonstrated. To attain CARS image with high- speed, correcting chromatic aberration is focused on. The split between the focal spots of two lasers passed through the lens tubes is 21 μm and a numerical simulation shows that the intensity of CARS signal by correcting the chromatic aberration is 2.3 times as strong as non-correcting. The rigid endoscope has been modified to suppress the chromatic aberration by using two single-mode fibers which deliver the two lasers individually. The experimental result shows the increase of CARS intensity at least 1.5 times.
(Introduction) The color information of the conventional endoscopic image is displayed by RGB coordinates, but this color information is changed by the distance, even same tissue. (Purpose) We try to conform that HSV coordinates and the virtual spectroscopic image to suppress the change of color information of the endoscope. Then we evaluate the verification of HSV coordinates and virtual spectroscopy by comparing with the absolute spectral by the liquid crystal tunable filter. (Result) We confirmed that the difference between HSV coordinates image and virtual spectral image and the absolute spectral image. Then the HSV coordinates suppress the color information change by distance. Also virtual spectral image is almost same result. (Conclusion) We confirmed that the HSV coordinates image makes suppress the change of color. Moreover, we had created a virtual spectroscopic endoscope image by using endoscope light, it is possible to suppress the change of color information by this method.
(Introduction) The endoscope was applied in various fields, but, on the other hand, the data volume increased, and the burdens on doctor increased. (Purpose) We make the highly precise automatic detection system of the bleeding region to reduce the burden of the diagnostician. (Method) It is HSV coordinates has H (Hue), S (Saturation), V (Value)). And hue depends on a wavelength.Then, we thought that it could be applied to automatic recognition of the disease by hue. (Results) Especially the bleeding region was detected by HSV coordinates more precisely than the previous study. If it was the HSV image, we were able to detect precisely the bleeding region of the upper gastrointestinal mucosa by hue. (Conclusion) If it was endoscopic image by the HSV indication, a bleeding region extremely had good precision, and automatic detection was possible.
The objective of this study was to establish a method enabling us to control microarchitectures of spheroids. We injected 1 μl of culture medium suspending Hep G2 cell and alginate hydrogel beads into a 3% methylcellulose medium. The beads were 20 μm in diameter. The injected cells and beads were rapidly aggregated in 10 min, and formed hybrid spheroids in 24 h. Microchannel structures were constructed by enzymatic digestion of the beads. In a different experiment, injection of Hep G2 cells and HUVECs resulted in forming microstructures by autonomous cellular rearrangement. Another type of micropattern was able to be obtained by injecting HUVECs and small-spheroids. Dissolved polymeric molecules like ECMs were also possible to be concentrated together with Hep G2 cells. The amount of polymeric molecules existing inside of the spheroids was tunable by changing its concentration. These data show that our method is useful to engineer microarchitectures of spheroids.
Master-slave remotely controlled manipulators such as the da Vinci systems have been developed to support for laparoscopic surgery. The manipulator is the all-in-one system constructed by integrating sub-systems such as the tool mounted arm mechanism, the DC servo actuator and the bilateral feedback controller. Thus, it is difficult to apply another development sub-system for the manipulator. To this end, we propose a modularized manipulator constructed by the tool changeable wire-driven flexible arm, the wire wind-up pulley and the actuator unit which can be interchanged between stepper motors and DC motors.
Screening test for sleep apnea syndrome using pulse oximetry is often performed at home. However, the subjects with a sensor probe have a harmful influence on the quality of sleep. In our previous reports, we have confirmed that there is a good correlation between the brightness variation (BV) signal of RGB camera by the Microsoft Kinect for Windows (Kinect v1) and the digital pulse volume by photo-plethysmography. Recently, Microsoft has released the Kinect for Windows v2 (Kinect v2), which much improved the resolution of RGB camera and the accuracy of depth sensor. The present study concerns with determination of a region of interest using Kinect v2. Moreover, we have also evaluated the impact of BV signal on the movement of the body surface. Consequently, the cheek is suitable for measurement. In addition, it seems to be considered that there is no effect of body motion for BV signal.
Many people complain of sleep problems in Japan. Therefore, many studies challenge to develop technologies for assessing and improving sleep quality. However, little studies have statistically described and visualized the major components underlying normal sleep structures based on physiological data. In this study, a laboratory-based polysomnography (PSG) was performed for consecutive two nights in 56 healthy young adults (male = 31, female = 25). To physiologically characterize sleep, the data of the second night were scored according to the standard rules. Sleep stages were classified into REM sleep and NREM sleep, the latter of which were further classified into light and deep sleep. Then the indexes such as the latency and percentage of these sleep stages were calculated and the correlations among these indexes were assessed. After principal component (PC) analysis was adopted for these indexes, three components were identified for describing normal sleep structure: a cumulative contribution ratio from the first PC to the third PC was more than 90%.
The drowsiness detection system has been developed because the traffic accident caused by the doze during driving does not decrease. The drowsiness detection systems use the various biological information, e.g. heart rate variability and eye movement. These methods are burdensome because they need recording electrodes. The commercially available doze detection system is only available as an option of deluxe car. Thus, the doze detection system still does not become popular. The drowsiness detection system using conventional device in low price is effective to become widely used and reduce traffic accidents.We have developed the doze detection system using only blink information. This system can detect the drowsy state in low arousal level. However the system cannot detect the drowsiness and alarm in real-time because the system operates off-line. In this study, the real-time doze detection algorithm was implemented in a smartphone and the accuracy of doze detection system was evaluated.
We proposed a technique of variable window-width of Moving-Average Method to extract only the pulse wave signals from the output signals of radars installed underneath the mattress, which enabled to calculate the heartbeat intervals.We applied a canonical discriminant analysis to classify the four sleep stages using the heart rate variability (HRV) derived from 10 students. LF/HF had a high degree of contribution to discriminate between LIGHT and DEEP sleep, and it was showed that the sleep cycle could be estimated (Figure).For the further improvement, we attempted to introduce a new decision tree analysis using not only HRV but also body movement index and respiratory interval indices.
Prior to the development of portable heat stroke screening system which stratifies excessive deep body temperature elevation (37.5 degrees) using a radar and thermopile, we conducted exercise stress tests which induces deep body temperature elevations using an ergometer (100W,15 minutes) for nine subjects (male, 21~24 years). We defined excessive deep body temperature elevation (EDT) when deep body temperature exceeds 37.5 degrees. We conducted linear discriminant analysis which stratifies EDT using fifteen minutes heart rates, respiratory rates and body surface temperatures measured after exercise load. The tests achieved 90.5% sensitivity, while, positive predictive value was 47.5%.
Chronic sleep apnea disorder is likely to bring the declining the sleep quality, getting out of sleep rhythm, and decrease of the blood oxygen levels. Particularly, the patient with chronic heart failure, it worsens imbalance of oxygen transfusion/consumption balance, modulation of neurohumoral factor activity and increase heart load. Consequently, they become a cause of worsening heart failure, and have a significant impact on the prognosis. Therefore, we need to find breathing disorder at early stage, lead to treatment. Currently, there are the monitoring system using PSG, Respiration Stability Index(RSI). It is said RSI can monitor the stability of breathing cycle, sleep quality by analyzing frequency. Currently it has been developing wearable or non-contact monitor.
In this study, we detected the motion of chest from images shot by non-contact with Depth camera. Furthermore we analyzed comparison with the result of the evaluation of respiratory condition acquired by respiratory sensor.
It has become feasible to monitor individual heart rate variability for the health care on a daily bases based on the rapid development of IoT sensor networking system. For the precise characterization of the heart rate variability over 24 hours, the segmentation of the data to differentiate sleep period is important. This paper proposes a method of automatic detection of sleep period from 24 hour RRI intervals. Weighted spline smoothing technique has been introduced for the segmentation. Weight function in the spline smoothing optimizing function controls the balance between the data fitness and smoothness. The method adaptively decrease the smoothness factor where the rate of data discrepancy increases. The method enables the natural trend estimation for the accurate segmentation. Computer simulation assuming the presence of additive 1/f fluctuations revealed the effectiveness of the method. The method will be useful for the automatic analysis of Holter ECG big data
Integration of IoT and cloud data storage/management technology have been an emerging field of study for developing the next generation health care system. Standardized biosignal data format will take a key role. In this study, a new data format of heart rate variability based on ISHNE framework is proposed. In the data format, one beat information including the beat annotation is stored in a 16 bit word. The format enables the life-long heart beat recording with reasonable storage size. The format will be useful for daily health monitoring.
It is important to inhibit thrombus formation in a blood pump applicable to severe heart failure patient. Blood coagulation reaction are different depend not only on the blood coagulability of the patients but also on the degree of shear stress. However, it is not clear the relationship between the degree of shear stress and the amount of thrombus. The, we utilized a rheometer which is able to load homogeneous shear stress to the test blood, and measured blood coagulation time and the amount of thrombus for bovine blood. As a result, blood coagulation reaction time became long with the increase in shear stress, but the amount of thrombus was almost the same at same shear stress even in different ACT test blood. We also obtained that the inhibition mechanism of blood coagulation reaction under shear stress was related to the blood coagulation factor V for porcine and human blood.
This paper describes the visualization of thrombus formation on shear flows such as orifice flow and Cuette flow, and development of numerical simulation for predicting thrombus formation by transport equation. Using the transparent devices, the thrombus formation on the wall on shear flow is observed and obtained the rate of thrombus formation by image processing. The results showed that the thrombus rate is increasing with shear rate by changing geometries of orifice and rotational speed of Cuette flow. On the other hand, the prediction method using CFD including transport equation of species using modified shear dependent model in orifice flow and Cuette flow is developed. In this computation, activated platelet is evaluated. The results show that deposition rate of activated platelet is increasing with shear rate.
In the study of biological effects of ELF electric field, we found that the blood flow changes when the field is exposed to our body. The aggregability of red blood cells (RBC's)in vivo increases right after the field exposure. To elucidate this phenomenon, an experimental study was conducted. Electric field was applied to the blood sample on a slide glass using insulated metal electrodes to make the current density 100 mA/m2 which simulates the current induced inside an adult body with a therapeutic instrument of electric field exposure. As a result, the ratio of the aggregated RBC's increased about 25% in the field exposure. Through this study, the change in the RBC aggregability was confirmed in the well-controlled in vitro measurement. This suggests the possibility that the blood property change is caused not by the physiological change but by the physical change that is observ-able in the in vitro condition.
The multi-point laser Doppler velocimetry (MLDV) is an established method for measuring the microcirculatory blood flow. The LDV can noninvasive measure the absolute blood flow velocity in measurement region in skin. In general, the fringe pattern was created in intersection region [i.e., measurement region] by two laser beams. However, the influence of skin structure to give the laser beams and measurement results was not discussed. In this paper, we observed photographs of the interference fringes formed in subcutaneous tissue of chicken. In the case of narrow position in skin, fringe pattern was almost kept but it becomes an interference pattern like a laser speckle pattern in deeper position. It is shown that the fringe pattern including speckle pattern is formed at the intersection point. As these results, we can show the limit of depth in the skin related to the fringe or speckle pattern and intensity of Doppler signals.
To examine how cardiovascular adaptation to chronic hypoxia might evolve, the responses to blood pressure (Pt) and hematocrit (Ht) during long-term systemic exposure to hypoxia were observed in awaked rats. Furthermore, the total peripheral vascular resistance (TPR) was estimated using direct measurements of systemic blood pressure (Ps) and blood flow (Qs) in carotid artery based on Darcy's law (TPR=Ps/Qs), and evaluated the remodeling procedure in the microcirculation in hypoxia. Pt and Ht under normoxic conditions were kept almost constant, while hypoxic exposure immediately increased Ht from 45% to 58% and, thereafter, it remained stable. The TPR values showed no significant differences between hypoxic and normoxic conditions. These results suggest that effects of high viscosity caused by increasing Ht on peripheral vascular resistance can be compensated by inducing microvascular remodeling with the arteriolar dilation and capillary angiogenesis.
Although various cellular immune therapies have been developed, because the therapeutic cells disperse in blood flow, there is a limitation on the accumulation of the cells to the target area. Thus we propose a new method of carrying therapeutic cells using microbubbles and ultrasound, where microbubbles attach on the surface of the cells, because acoustic force to propel the cells is increased. Using microbubbles and Colon-26 cells, we succeeded to produce their aggregations. Then we verified the controllability of the aggregations under continuous ultrasound exposure. According to the exposure time and the sound pressure, we confirmed the controllability of the aggregatiions decreased.
The optimal SD distance for functional near infrared spectroscopy of macaque monkey has investigated with the simulation calculations of light propagation in the sophisticated head model. T1- and T2-weighted images of monkeys (N=2) were segmented into 6 regions. Optical properties assigned to each region were referred from literatures. A pair of probes was located on the scalp surface above the motor cortex with changing the SD distance (10, 15, 20 and 25 mm) and the direction (perpendicular or parallel to central sulcus). The analytical solution of the diffusion equation was calculated by the finite element method. The detected intensity and partial optical path length in the gray matter was decreased and increased by the increase of the SD distance, respectively. The product of the intensity and the path length showed high value for the SD distance was 15 mm regardless of subjects and directions.
We used the International Affective Picture System (IAPS) which is increasingly used in brain imaging studies to examine emotional processes. Their images also allow arousal to be systematically investigated. Eighty IAPS images of low, neutral and high arousal. Those images were randomly presented for 2.0 s on screen set at 200 cm in front of the subject. Ten healthy subjects participated. MEG recordings were made with a 306-channel whole-head MEG system in a magnetically shielded room. The amplitude of the N1 source in the occipital area was larger in the neutral arousal images than the low and high arousal images. This result suggests that the amplitude of N1 that originated from the visual region was modulated by arousal of the image.
Binaural cortical responses are mixtures of inputs from both ears.We introduce here "dichotic listening test" that speech sound used to selectively follow these inputs in humans up to the cortex during binaural hearing.We recorded neuromagnetic cortical responses with magnetoencephalogram (MEG) to amplitude-modulated speech sound, with different modulation frequencies at each ear.During binaural hearing, the left- and the right- ear inputs compered strongly in both auditory cortices: The right-hemisphere responses were symmetrically suppressed, whereas the left-hemisphere responses were suppressed significantly more for ipsilateral than contralateral sound, thereby intensifying the right-ear dominance of the left auditory cortex. This type of hemisphere-and ear-selective information on cortical binaural interaction could have new auditory check.
Implanting electrodes for recording the neural signals in the deep brain regions is promising to observe various physiological phenomena, and add a number of their applications. For those purposes, it is important to place the electrodes made of bio-compatible materials in the target regions precisely.
This work has discussed the feasibility of titanium wires, which were known for their high bio-compatibility and weak magnetism, as neural electrodes.
The titanium and tungsten wires coated with Parylene polymer were implanted in the rat brain. For each electrode, the signal measurement abilities in the acute experiment and the characteristics in magnetic resonance imaging (MRI) scan were confirmed.
Our results showed that the recorded signals and the MR images had no remarkable differences in their signals and images property, which suggested possibility of utilizing titanium wires, as well as conventional tungsten wires, for recording neural signals in the deep brain regions.
The purpose of this study is to investigate melody recognition processes in the brain using ambiguous auditory stimuli. Some stimuli we encounter in our environment are ambiguous. Necker cube is a famous example in vision. However, it has not been studied systematically in hearing. We proposed a novel form of ambiguity involving two illusory melodies implied by a very simple stimulus consisting of two sustained tones (A4 and E5) and an intermittently repeated tone (C5). One heard either the phrase C5-A4-C5-A4, C5-E5-C5-E5, or the physical stimulus, that is the repeated middle tone. We presented introductory melodies (C5-A4-C5-A4 or C5-E5-C5-E5) to reduce ambiguity before starting ambiguous melodies. We then measured the transition time that elapsed until the subject heard a different melody from the introductory melody. In this report, we used B4 or D5 for intermittently repeated tone other than C5 to investigate how transition time changed. The different behaviors for different middle tones had some bearing on how one preferred to or tended to form a melody in one's mind. When repeated tone was D5, D5-E5-D5-E5 tended to be preferred to D5-A4-D5-A4. There was no preference between upward and downward phrase for B4.
Context contributes to accurate and efficient information processing, and shapes perception, thoughts and actions. Contextual information allows for context-driven predictions or expectations, along with predictive coding, which is a guiding principle of efficient information processing in the brain. To reveal the dynamics of the neural mechanisms underlying the processing of the association context during recognition of colored objects (i.e., association between color and object)., we carried out functional magnetic resonance imaging (fMRI) experiments, in which subjects were asked to judge contextual validity for the association context. Here, naturally colored objects are valid-context stimuli, while unnaturally colored objects are invalid-context stimuli. We showed the activation maps (regions of activation) for the task of the judgment of contextual validity for the association context. By the dynamic causal modeling (DCM) analysis, we revealed the dynamic nature of the neural connectivities in the contextual information processing.
It is important to know how spontaneous activity patterns of neuronal network are modulated by alteration in ratio and connections between excitatory (glutamatergic) and inhibitory (GABAergic) neurons in order to elucidate the contribution of GABA-mediated inhibition to maintenance of cortical function. Our purpose is to construct neuronal networks with various excitatory/inhibitory conditions in vitro using induced pluripotent stem (iPS) cell, and to analyze activity patterns of neuronal network. First, mouse iPS cells were induced to differentiate into excitatory or inhibitory neurons selectively. Second, these neurons were cultured on a microelectrode array under several network conditions, and neuronal activity was recorded. As a result, spontaneous network activities of iPS cell-derived neurons were observed, and pharmacological experiments indicated that the activities depended on strength and amounts of excitatory and inhibitory synaptic transmissions. Moreover, neuronal oscillations with different frequencies and active-phase durations were observed when neuronal excitatory/inhibitory ratio and connections were altered.
[Introduction] Neurovascular unit (NVU) is composed of neural cells, blood vessels and extracellular matrix. Although functions of neural cells have been investigated at the single-cell level, those at the multi-cellular level are not clear. Here, we investigated conditions for the coculture of neural stem cells (NSCs) and brain endothelial cells (ECs) to construct NVU by using a microfluidic device. [Methods] Microfluidic devices which have a central channel sandwiched by two parallel microchannels were used in this study. After injecting gel scaffolds into the central channel, NSCs or ECs were seeded into one of the microchannels. The effect of gel compositions on neurogenesis and angiogenesis was investigated. [Results and Discussion] NSCs or ECs were cultured in different gel compositions in a microfluidic device. Three-dimensional neurite extension and capillary formation were promoted in fibrin-Matrigel mixed gel. These results suggested that this culture condition is useful to construct NVU in a microfluidic device.