•Small coils (4 mm diameter) were constructed with a core to stimulate mouse cortex.•The coils delivered magnetic stimulation at a millimeter-scale spatial resolution.•Coil simulation estimated ...induction of electric fields over the spike threshold.•Experimental stimulation induced spikes and local field potentials in the cortex.•Our small coil technique could produce effective magnetic and electric fields.
Transcranial magnetic stimulation (TMS), a minimally/non-invasive method of electromagnetic stimulation of brain tissue, has been shown to be beneficial in clinical therapy for specific neurological diseases and disorders. Magnetic stimulation is also used to modulate human and animal brain activity in basic neuroscience studies. Among experimental animal models, mouse models are particularly popular and uniquely representative of brain disorders in basic neuroscience research. TMS in mouse models may play a substantial role in understanding TMS-induced changes in neural networks and plasticity. Although TMS techniques are widely used to examine rodent disease models, techniques specific for mice using small magnetic stimulators have not been intensively developed. Here, we provide a numerical simulation and a practical method of applying TMS to mice by constructing millimeter-sized TMS coils to deliver a low stimulation intensity while maintaining focality. Our results indicate the TMS coils can produce an electrical field with sufficient magnitude to activate the anesthetized mouse cortex in the presence or absence of the skull in vivo. Our results also show that, immediately after magnetic stimulation, local field and action potentials were reliably observed in a manner that depended on the distance between the coil and the brain, implying even a small coil could reliably evoke cortical activity. Therefore, our results show our millimeter-sized coils could produce electric fields sufficient to alter cortical excitability in mice. These coils could be useful in future preclinical studies to examine detailed mechanisms underlying TMS-induced changes in neural activity of the auditory cortex and other cortical regions.
Abstract
The carrier collection efficiencies of InGaAs/GaAsP superlattice (SL) photovoltaic structures were optimized by choosing adequate manufacturing parameters, such as the composition and ...thickness of the quantum wells (QWs) and barrier layers. However, no insights have been observed from the viewpoint of the nonradiative transition of photoexcited carriers. In this study, piezoelectric photothermal (PPT) and photoluminescence (PL) measurements were performed as a function of temperature from 100 to 340 K. Using a piezoelectric transducer, the PPT signal detected the heat generated by nonradiative recombination (NR). The indium composition of the QW layer was fixed at 0.3, and the phosphorus composition xP in the barrier layer was changed from 0.4 to 0.6. The observed temperature dependences of the PPT and PL signal intensities were analyzed using a rate equation for the photoexcited carriers in e1 and hh1 quantized levels. Four carrier dissipating processes, namely, radiative recombination, NR, thermal escape from the QW thermal excitation (TE), and tunneling after thermal excitation (TATE), were considered for both electrons and holes. Thermal activation energies were included in the NR, TE, and TATE processes. Because nonradiative and radiative transition components cause PPT and PL signals, curve fitting of the temperature behavior enabled us to determine the activation energies. We then found that the activation energy of the NR process reached a maximum at xP = 0.45. No such maxima were observed for the TE and TATE process. This result was explained by a trade-off between the strain valance condition over the entire range of the SL structure and the local residual strain at the interfaces between the QW, interlayer, and barrier layer when xP increased. Because no software can theoretically calculate the activation energy of the NR process, we demonstrated the usefulness of the present PPT experimental methodology for investigating carrier transport properties.
Although endothelial damage has been hypothesized to be associated with coronavirus disease 2019 (COVID-19)-related cerebral infarction based on the specificity of the viral cellular invasion ...pathway, no case has been reported to date. We herein report a 51-year-old Japanese woman who presented with neck pain one week after COVID-19 infection. Computed tomography and magnetic resonance imaging revealed inflammation of the carotid and vertebral arteries. Ultrasonography revealed multiple flap-like structures that were assumed to be thrombi. Although the patient had no cerebral infarction, this could be an important case of vascular damage and thrombus formation in a COVID-19 patient.
Abstract
The performance of magnonic devices such as converters, switches, and multiplexers greatly depends on magnonic noise. While a peculiar discrete magnonic noise has been previously reported, ...the sources of underlying magnon dynamics occurring in high-magnon density conditions have not been clarified. Here, zero-span measurements of the spectrum analyzer were recorded to accurately detect magnonic noise as a fluctuation of the spin-wave amplitude. The results of low-frequency magnonic noise demonstrated a spin-wave mode dependency, indicating the existence of a peculiar magnon surface state. Furthermore, the energy thresholds of four-magnon scattering and autooscillation were determined using magnonic white noise. The noise data obtained in this study can help promote theoretical and experimental research on magnons.
It has been reported that the use of mitochondrial RNA aptamers including RNase P (RP) results in the selective mitochondrial delivery of endogenous and exogenous RNAs. The issue of whether these ...aptamers would be useful ligands for the mitochondrial targeting of a nanoparticle has not been demonstrated to date because nanocarriers modified with these RNA aptamers are insufficiently internalized by cells. We report here on the development of a dual-ligand liposomal system composed of octaarginine (R8), a device that enhances cellular uptake, and an RP aptamer for mitochondrial targeting to permit a nanocarrier to be efficiently delivered to mitochondria. Surprisingly, the cellular uptake of the R8-modified nanocarrier was facilitated by modification with an RP aptamer. The optimal composition of a nanocarrier needed for efficient cellular uptake and mitochondrial targeting was determined. In a confocal laser scanning microscopy analysis, the dual-ligand-modified nanocarrier was found to result in effective mitochondrial targeting through an ATP-dependent pathway and was much more effective than a single-ligand R8-modified nanocarrier. This is the first report of the regulation of intracellular trafficking by a mitochondrial RNA aptamer-modified nanocarrier system.
Ultrasound stimulation is expected to be useful for transcranial local and deep stimulation of the brain, which is difficult to achieve using conventional electromagnetic stimulation methods. ...Previous ultrasound stimulation experiments have used various types of acute
preparations, including hippocampus slices from rodents and Caenorhabditis elegans tissue. For
preparations, researchers have used the cortices of rodents as targets for transcranial ultrasound stimulation. However, no previous studies have used
ultrasound stimulation in rodent cortical slices to examine the mechanisms of ultrasound-driven central neural circuits. Here we demonstrate the optimal experimental conditions for an
ultrasound stimulation system for measuring activity in brain slices using a multielectrode array substrate. We found that the peak amplitudes of the ultrasound-evoked cortical responses in the brain slices depend on the intensities and durations of the ultrasound stimulation parameters. Thus, our findings provide a new
experimental setup that enables activation of a brain slice
ultrasound stimulation. Accordingly, our results indicate that choosing the appropriate ultrasound waveguide structure and stimulation parameters is important for producing the desired intensity distribution in a localized area within a brain slice. We expect that this experimental setup will facilitate future exploration of the mechanisms of ultrasound-driven neural activity.
The acquisition of micro-vibrations is important for analyzing machinery. In the present study, we propose a method for measuring and visualizing the three-dimensional (3D) displacements of such ...micro-vibrations, especially in the case of sound waves propagating through space. The proposed method uses the speckle patterns of coherent light to measure the minute displacements. Speckle patterns are useful for detecting extremely small displacements owing to their sensitivity to the pose of the object. However, it is impossible to measure the displacement at each position because the pattern changes nonlinearly with respect to large depth changes. Therefore, a method of nonlinear low-dimensional embedding of the speckle pattern is proposed to analyze the displacements and extended to measure micro-displacements in a 3D space. We divided the 3D space into multiple slices and synchronously captured each speckle pattern. The displacements in the entire 3D space were simultaneously recovered by optimizing the embedded vectors, which were consistent in a 3D lattice. The propagation of sound waves in the 3D space was visualized using the volume-rendering technique. The experiments confirmed that the proposed method correctly measured the displacements by comparing them with the ground truth captured by microphones. We also visualized the wavefront of the sound wave propagating through space.
Reconstructing 3D shapes from images are becoming popular, but such methods usually estimate relative depth maps with ambiguous scales. A method for reconstructing a scale-preserving 3D shape from ...monocular endoscope image sequences through training an absolute depth prediction network is proposed. First, a dataset of synchronized sequences of RGB images and depth maps is created using an endoscope simulator. Then, a supervised depth prediction network is trained that estimates a depth map from a RGB image minimizing the loss compared to the ground-truth depth map. The predicted depth map sequence is aligned to reconstruct a 3D shape. Finally, the proposed method is applied to a real endoscope image sequence.
The coiled-coil motif mediates subunit oligomerization and scaffolding and underlies several fundamental biologic processes. Prohibitins (PHBs), mitochondrial inner membrane proteins involved in ...mitochondrial homeostasis and signal transduction, are predicted to have a coiled-coil motif, but their structural features are poorly understood. Here we solved the crystal structure of the heptad repeat (HR) region of PHB2 at 1.7-Å resolution, showing that it assembles into a dimeric, antiparallel coiled-coil with a unique negatively charged area essential for the PHB interactome in mitochondria. Disruption of the HR coiled-coil abolishes well-ordered PHB complexes and the mitochondrial tubular networks accompanying PHB-dependent signaling. Using a proximity-dependent biotin identification (BioID) technique in live cells, we mapped a number of mitochondrial intermembrane space proteins whose association with PHB2 relies on the HR coiled-coil region. Elucidation of the PHB complex structure in mitochondria provides insight into essential PHB interactomes required for mitochondrial dynamics as well as signal transduction.
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•Heptad repeat (HR) region of PHB2 is essential for PHB complexes in mitochondria•The HR region of PHB2 assembles into a dimeric, anti-parallel coiled-coil•Disruption of the PHB2 coiled-coil abolishes mitochondrial dynamics•The coiled-coil associates with mitochondrial proteins, invoking an immune response
Molecular Biology; Cell Biology; Structural Biology
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