Enhanced auditory responses in visual cortex of blind rats using intrinsic optical signal imaging.

Functional maturation of the visual cortex is induced by visual experiences during critical periods. Blind animals and humans exhibit improved auditory abilities after losing their vision. Here we investigated the response of the visual cortex to white noise stimuli during the progression of photoreceptor degeneration in a rat model of blindness (Royal College of Surgeons [RCS] (rdy/rdy) rats).

Thyroid hormone insufficiency alters the expression of psychiatric disorder-related molecules in the hypothyroid mouse brain during the early postnatal period.

The functional role of thyroid hormone (TH) in the cortex and hippocampus of mouse during neuronal development was investigated in this study. TH insufficiency showed a decrease in the expression of parvalbumin (PV) in the cortex and hippocampus of pups at postnatal day (PD) 14, while treatment with thyroxine from PD 0 to PD 14 ameliorated the PV loss. On the other hand, treatment with antithyroid agents in adulthood did not result in a decrease in the expression of PV in these areas.

Multimodal Functional Analysis Platform: 4. Optogenetics-Induced Oscillatory Activation to Explore Neural Circuits.

To elucidate neural mechanisms underlying oscillatory phenomena in brain function, we have developed optogenetic tools and statistical methods. Specifically, opto-current-clamp induced oscillation reveals intrinsic frequency preferences in the neural circuits by oscillatory resonance. Furthermore, resonance or entrainment to intrinsic frequency is state-dependent.

Multimodal Functional Analysis Platform: 3. Spherical Treadmill System for Small Animals.

In the application of advanced neuroscience techniques including optogenetics to small awake animals, it is often necessary to restrict the animal's movements. A spherical treadmill is a beneficial option that enables virtual locomotion of body- or head-restrained small animals. Besides, it has a wide application range, including virtual reality experiments.

Multimodal Functional Analysis Platform: 2. Development of Si Opto-Electro Multifunctional Neural Probe with Multiple Optical Waveguides and Embedded Optical Fiber for Optogenetics.

We have developed a Si opt-electro multifunctional neural probe with multiple waveguides and embedded optical fiber for highly accurate optical stimulation. The Si opt-electro multifunctional neural probe had 16 recording sites, three optical waveguides, and metal cover for suppressing light leakage. The other opt-electro multifunctional neural probe had an optical fiber in the trench of the probe shank, which leads to fewer damages to tissues.

Multimodal Functional Analysis Platform: 1. Ultrathin Fluorescence Endoscope Imaging System Enables Flexible Functional Brain Imaging.

To elucidate the expression mechanisms of brain functions, we have developed an ultrathin fluorescence endoscope imaging system (U-FEIS) that can image cells in the brain at any depth while minimizing the invasion. The endoscope part of U-FEIS consists of a GRIN lens and a 10,000-pixel image fiber with a diameter of 450 μm. The specialized microscope of U-FEIS is within 30 cm square and includes lenses and optical filters optimized for the endoscope.

Resting-state functional connectivity analysis of the mouse brain using intrinsic optical signal imaging of cerebral blood volume dynamics.

Objective: Resting-state functional connectivity (rsFC) of the human brain is closely related with neurological and psychiatric disorders. Mice are widely used to investigate the physiological mechanisms of such disorders, because of the applicability of invasive experimental techniques. Thus, studies on rsFC of the mouse brain are essential to link physiological mechanisms with these disorders in humans.

Some adverse actions of chlorothalonil at sublethal levels in rat thymic lymphocytes: Its relation to Zn.

Chlorothalonil, a polychlorinated aromatic fungicide, is considered non-toxic to small mammals. However, chlorothalonil inactivates sulfhydryl enzymes and depletes cellular glutathione. Chlorothalonil increases intracellular Zn concentration ([Zn]i) in mammalian cells possibly because intracellular Zn is released via zinc-thiol/disulfide interchange.

Evaluation of multidrug cancer chronotherapy based on cell cycle model under influences of circadian clock.

The intracellular circadian clock mechanisms are known to affect various substantial cellular machinery such as cell cycle progression, inflammatory response, apoptosis, and DNA repair. Cancer growth in various tissues is still under circadian control, which may be at least partly underlain by the survived connections between the intracellular machinery and the clock. Considering such findings, chronotherapy has been applied to cancer treatments, in which anti-cancer drugs are administered in scheduled circadian times so as to resolve the trade-off between damages against the normal and cancer cells.

Reduction of light source noise from optical intrinsic signals of mouse neocortex by using independent component analysis.

Because the optical intrinsic signal (OIS) of the brain is very weak, noise reduction is essential. Independent component analysis (ICA) is widely used for noise reduction. However, the applicability of ICA to the reduction of light source (LS) noise has not been discussed in detail.

Entrainability of cell cycle oscillator models with exponential growth of cell mass.

Among various aspects of cell cycle, understanding synchronization mechanism of cell cycle is important because of the following reasons. (1)Cycles of cell assembly should synchronize to form an organ. (2) Synchronizing cell cycles are required to experimental analysis of regulatory mechanisms of cell cycles.

Reconstruction of fetal vector electrocardiogram from maternal abdominal signals under fetus body rotations.

Fetal electrocardiogram (fECG) and its vector form (fVECG) could provide significant clinical information concerning physiological conditions of a fetus. So far various independent component analysis (ICA)-based methods for extracting fECG from maternal abdominal signals have been proposed. Because full extraction of component waves such as P, Q, R, S, and T, is difficult to be realized under noisy and nonstationary situations, the fVECG is further hard to be reconstructed, where different projections of the fetal heart vector are required.

Development of distance-selective nerve recruitment for subcortical brain mapping by controlling stimulation waveforms.

During brain surgery, it is important to determine the functional brain area and cortico-cortical pathways so as to keep them intact and preserve patients' quality of life. Cortical and subcortical brain mappings are techniques that deliver direct current stimulation to the brain surface and beneath gray matter to identify the brain area and nerve fibers related to higher-order functions. However, because of the non-selective effect of conventional electrical stimulation methods, it has been difficult to obtain precise spatial distribution of nerve fibers in the subcortical region.

Inhibitory effect of cervical trachea and chest wall vibrations on cough reflex sensitivity and perception of urge-to-cough in healthy male never-smokers.

Background: Non-pharmacological options for symptomatic management of cough are desired. Although chest wall mechanical vibration is known to ameliorate cough reflex sensitivity, the effect of mechanical vibrations on perceptions of urge-to-cough has not been studied. Therefore, we investigated the effect of mechanical vibration of cervical trachea, chest wall and femoral muscle on cough reflex sensitivity, perceptions of urge-to-cough as well as dyspnea.

Suppression of anodal break excitation by electrical stimulation with down-staircase waveform for distance-selective nerve recruitment.

Electrical nerve stimulation using extracellular electrodes is widely performed in clinical medicine as well as basic medical science. It has been reported that selective recruitment of nerve fibers on the basis of the distance between the electrode and the axon is possible without moving the electrode and only by modifying the waveform of electrical stimulation. However, computer simulations have not reproduced the complete nature of the distance-selectivity of the stimulus owing to the difficulty in numerical analysis.

Separation of multiunit signals by independent component analysis in complex-valued time-frequency domain.

Multiunit recording with a multi-electrode in the brain has been widely used in neuroscience studies. After the data recording, neuronal spikes should be sorted according to spike waveforms. For the spike sorting, independent component analysis (ICA) has recently been used because ICA potentially solves the problem to separate even overlapped multiple neuronal spikes into the single.

Parameter exploration of staircase-shape extracellular stimulation for targeted stimulation of myelinated axon.

Spatio-temporal dynamics of a mathematical model of myelinated axon in response to staircase-shape extracellular electrical stimulation, which was developed for selective nerve stimulation, is investigated by the computer simulation. It is shown that the response is classified into four types: subthreshold response, cathodic excitation, anodal block and anodal break excitation. Based on the simulation results, simple diagrams representing the response characteristics of the axon are constructed as functions of stimulation parameters and distance between the axon and electrode.

Enhancement of synchronization between hippocampal and amygdala theta waves associated with pontine wave density.

Theta waves in the amygdala are known to be synchronized with theta waves in the hippocampus. Synchronization between amygdala and hippocampal theta waves is considered important for neuronal communication between these regions during the memory-retrieval process. These theta waves are also observed during rapid eye movement (REM) sleep.

Multi-neuron action potentials recorded with tetrode are not instantaneous mixtures of single neuronal action potentials.

Multiunit recording with multi-site electrodes in the brain has been widely used in neuroscience studies. After the data recording, neuronal spikes should be sorted according to the pattern of spike waveforms. For the spike sorting, independent component analysis (ICA) has recently been used because ICA has potential for resolving the problem to separate the overlapped multiple neuronal spikes.

The 3D position estimation of neurons in the hippocampus based on the multi-site multi-unit recordings with silicon tetrodes.

The mechanical strain of the neural tissue induced by the implant of neuronal electrode is one of the important factors responsible for the quality and performance of extracellular recording of neuronal activities in the brain because the mechanical strain could kill or inactivate the neurons. In order to evaluate the effect of the implant of neural electrode, we propose a method to estimate the three-dimensional distribution of electrophysiologically active neurons near the electrode based on the multi-site multi-unit recording data. The spatial distribution of the active neurons emerges the region in the neural tissue that could be killed or inactivated by the implant of the electrode.

Robustness of the blind source separation with reference against uncertainties of the reference signals.

The fetal electrocardiogram (ECG) could provide clinical information concerning physiological conditions of the fetus. In order to extract fetal ECG, we proposed the novel algorithm, the blind source separation with reference (BSSR), which successfully extracts a complete waveform of QRS complex and avoids uncertainty in the order of the extracted signals. In the BSSR, the reference signal is supposed to be generated from the ultrasonic Doppler signal.

Phase-locking of spontaneous and tone-elicited pontine waves to hippocampal theta waves during REM sleep in rats.

Temporal relationships between hippocampal theta waves and pontine waves (P waves) during rapid-eye-movement (REM) sleep were investigated in rats. P waves were phase-locked to the positive theta peak. The phase relationships of P waves elicited by a tone stimulus (P(E) waves) to hippocampal theta waves were also analyzed to qualitatively clarify the mechanism of phase-locking between these two phenomena.

A novel extraction method of fetal electrocardiogram from the composite abdominal signal.

In contrast to the ultrasonic measurement of fetal heart motion, the fetal electrocardiogram (ECG) provides clinically significant information concerning the electrophysiological state of a fetus. In this paper, a novel method for extracting the fetal ECG from abdominal composite signals is proposed. This method consists of the cancellation of the mother's ECG and blind source separation with the reference signal (BSSR).

Measurement method for the fetal electrocardiogram.

A fetal electrocardiogram (ECG) provides clinically significant information concerning the electrophysiological states of a fetus. Since the first attempt by Cremer in 1906, for about 100 years nobody has been able to non-invasively extract the fetal ECG popularly used in clinical situations. The low amplitude of the fetal signals and the high background noise and the non-linearity of the ECG signals mainly have been interfering with the noninvasive extraction of the fetal ECG.

Tri-n-butyltin-induced blockade of store-operated calcium influx in rat thymocytes.

Tri-n-butyltin (TBT), one of environmental pollutants, disturbs intracellular Ca(2+) homeostasis by increasing intracellular Ca(2+) concentration ([Ca(2+)]i). Effect of TBT on oscillatory change in [Ca(2+)]i (Ca(2+) oscillation) of rat thymocytes was examined using a laser microscope with fluo-3-AM in order to further elucidate the TBT toxicity related to intracellular Ca(2+). The Ca(2+) oscillation was completely attenuated by 300nM TBT.