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Dopamine (DA) is the key regulator of reward behavior. The DA neurons in the ventral tegmental area (VTA) and their projection areas, which include the prefrontal cortex (PFC), nucleus accumbens (NAc), and amygdala, play a primary role in the process of reward-driven behavior induced by the drugs of addiction, including nicotine and alcohol. In our previous study, we developed a novel platform consisting of micro-LED array devices to stimulate a large area of the brain of rats and monkeys with photo-stimulation and a microdialysis probe to estimate the DA release in the PFC. Our results suggested that the platform was able to detect the increased level of dopamine in the PFC in response to the photo-stimulation of both the PFC and VTA. In this study, we used this platform to photo-stimulate the VTA neurons in both ChrimsonR-expressing (non-specific) wild and dopamine transporter (DAT)-Cre (dopamine specific) mice, and measured the dopamine release in the nucleus accumbens shell (NAcShell). We measured the DA release in the NAcShell in response to optogenetic stimulation of the VTA neurons and investigated the effect of GABAergic neurons on dopaminergic neurons by histochemical studies. Comparing the photo-stimulation frequency of 2 Hz with that of 20 Hz, the change in DA concentration at the NAcShell was greater at 20 Hz in both cases. When ChrimsonR was expressed specifically for DA, the release of DA at the NAcShell increased in response to photo-stimulation of the VTA. In contrast, when ChrimsonR was expressed non-specifically, the amount of DA released was almost unchanged upon photo-stimulation. However, for nonspecifically expressed ChrimsonR, intraperitoneal injection of bicuculline, a competitive antagonist at the GABA-binding site of the GABAA receptor, also significantly increased the release of DA at the NAcShell in response to photo-stimulation of the VTA. The results of immunochemical staining confirm that GABAergic neurons in the VTA suppress DA activa

In this study, a fabrication method for a system composed of a fluorescence imaging module and a multielectrode array (MEA) chamber is described. It is important to measure both fluorescence intensity and electrical activity to obtain a better understanding of a physiological activity, such as spikes or action potentials, of cells. However, observing these physiological traits long-term with cultured cells is difficult using a conventional microscope. In this study, we developed a small fluorescence imaging device with an MEA that can be used in a conventional CO2 incubator. The fluorescence imaging module was composed of a CMOS image sensor, a fiber-optic plate (FOP), a blue LED, and optical filters. The FOP enabled the device to be miniaturized through lensless fluorescence imaging. The MEA chamber was fabricated with micro gold electrodes deposited on the FOP. By using the FOP for the bottom of the chamber, we measured both the fluorescence signal and electrophysiology signal in the same experiment. The performance of the device was evaluated with neuronal blastoma cells. Our device enabled us to observe fluorescence images and MEA signals.

In this study, a dual-band hybrid filter that achieves high excitation light rejection performance in a lensless imaging system was fabricated and incorporated into an imaging device. The hybrid filter consisted of interference and absorption filters, and a fiber optic plate (FOP). The interference filters were attached to both sides of the FOP, which was placed on top of the absorption filter to suppress the decrease in spatial resolution. In addition, the lamination order was optimized to achieve a high fluorescence observation performance. The fabricated hybrid filter was mounted on an image sensor and had the ability to indicate the green and red fluorescence components.

Diagnosis by ocular fundus imaging plays a key role in the monitoring, detection, and diagnosis of several diseases including eye-related, hypertensive, and cardiovascular diseases as well as the detection of brain microvascular and neuronal pathology. The spectral detection of the fundus in the near-infrared (NIR) region can be used to analyze the composition and content of the fundus substance. The aim of this study was to develop a multichannel bandpass filter, which can be assembled on a CMOS image sensor installed in a fundus camera, to realize spectral imaging. We designed the filter in the NIR region according to interference filter theory and fabricated it by sputtering, lithography, and etching. The images acquired by the image sensor with the fabricated bandpass filter confirmed that the pixel values were comparable to the values calculated from spectrometer measurements. In an experimental validation, the number of measurement wavelengths was increased by applying the incident angle dependence of the interference filter. Each fabricated filter had a relatively wide transmittance band for spectral detection, broadening the spectrum curve. Moreover, a high-resolution spectrum was reconstructed using the developed algorithm. The spectrum reconstructed by the proposed filter had a 15% average relative error over the entire wavelength range of interest.

In this work, we present a simple complementary metal-oxide semiconductor (CMOS)-controlled photovoltaic power-transfer platform that is suitable for very small (less than or equal to 1–2 mm) electronic devices such as implantable health-care devices or distributed nodes for the Internet of Things. We designed a 1.25 mm × 1.25 mm CMOS power receiver chip that contains integrated photovoltaic cells. We characterized the CMOS-integrated power receiver and successfully demonstrated blue light-emitting diode (LED) operation powered by infrared light. Then, we integrated the CMOS chip and a few off-chip components into a 1-mm3 implantable optogenetic stimulator, and demonstrated the operation of the device.

This study proposes to adapt the fundus camera for use as a personal healthcare tool. The proposed system uses near-infrared light to avoid blinding the subject and three-wavelength near-infrared imaging to acquire colorized fundus images. First, the optical system with the fundus camera was tested using a three-plate near-infrared snapshot camera. Subsequently, image processing and denoising techniques, including tracking and image integration, were applied to reduce the blur caused by biological scattering. Furthermore, a singlechip three-wavelength near-infrared-compatible image sensor is required for device miniaturization, for which a dielectric multilayer Fabry-Perot bandpass filter was adopted as its transmission wavelength can be easily controlled. In this study, the optical design of the dielectric multilayer structure, the fabrication process of the mosaic filter, and the chip mounting technology are investigated. The demosaicing process and color space conversion corresponding to the spectral response characteristics of the fabricated image sensor are also discussed.

Dopamine (DA) is the key regulator of reward behavior. The DA neurons in the ventral tegmental area (VTA) and their projection areas, which include the prefrontal cortex (PFC), nucleus accumbens (NAc), and amygdala, play a primary role in the process of reward-driven behavior induced by the drugs of addiction, including nicotine and alcohol. In our previous study, we developed a novel platform consisting of micro-LED array devices to stimulate a large area of the brain of rats and monkeys with photo-stimulation and a microdialysis probe to estimate the DA release in the PFC. Our results suggested that the platform was able to detect the increased level of dopamine in the PFC in response to the photo-stimulation of both the PFC and VTA. In this study, we used this platform to photo-stimulate the VTA neurons in both ChrimsonR-expressing (non-specific) wild and dopamine transporter (DAT)-Cre (dopamine specific) mice, and measured the dopamine release in the nucleus accumbens shell (NAcShell). We measured the DA release in the NAcShell in response to optogenetic stimulation of the VTA neurons and investigated the effect of GABAergic neurons on dopaminergic neurons by histochemical studies. Comparing the photo-stimulation frequency of 2 Hz with that of 20 Hz, the change in DA concentration at the NAcShell was greater at 20 Hz in both cases. When ChrimsonR was expressed specifically for DA, the release of DA at the NAcShell increased in response to photo-stimulation of the VTA. In contrast, when ChrimsonR was expressed non-specifically, the amount of DA released was almost unchanged upon photo-stimulation. However, for nonspecifically expressed ChrimsonR, intraperitoneal injection of bicuculline, a competitive antagonist at the GABA-binding site of the GABAA receptor, also significantly increased the release of DA at the NAcShell in response to photo-stimulation of the VTA. The results of immunochemical staining confirm that GABAergic neurons in the VTA suppress DA activa, identifier:1422-0067

In this study, a fabrication method for a system composed of a fluorescence imaging module and a multielectrode array (MEA) chamber is described. It is important to measure both fluorescence intensity and electrical activity to obtain a better understanding of a physiological activity, such as spikes or action potentials, of cells. However, observing these physiological traits long-term with cultured cells is difficult using a conventional microscope. In this study, we developed a small fluorescence imaging device with an MEA that can be used in a conventional CO2 incubator. The fluorescence imaging module was composed of a CMOS image sensor, a fiber-optic plate (FOP), a blue LED, and optical filters. The FOP enabled the device to be miniaturized through lensless fluorescence imaging. The MEA chamber was fabricated with micro gold electrodes deposited on the FOP. By using the FOP for the bottom of the chamber, we measured both the fluorescence signal and electrophysiology signal in the same experiment. The performance of the device was evaluated with neuronal blastoma cells. Our device enabled us to observe fluorescence images and MEA signals., identifier:2435-0869

Diagnosis by ocular fundus imaging plays a key role in the monitoring, detection, and diagnosis of several diseases including eye-related, hypertensive, and cardiovascular diseases as well as the detection of brain microvascular and neuronal pathology. The spectral detection of the fundus in the near-infrared (NIR) region can be used to analyze the composition and content of the fundus substance. The aim of this study was to develop a multichannel bandpass filter, which can be assembled on a CMOS image sensor installed in a fundus camera, to realize spectral imaging. We designed the filter in the NIR region according to interference filter theory and fabricated it by sputtering, lithography, and etching. The images acquired by the image sensor with the fabricated bandpass filter confirmed that the pixel values were comparable to the values calculated from spectrometer measurements. In an experimental validation, the number of measurement wavelengths was increased by applying the incident angle dependence of the interference filter. Each fabricated filter had a relatively wide transmittance band for spectral detection, broadening the spectrum curve. Moreover, a high-resolution spectrum was reconstructed using the developed algorithm. The spectrum reconstructed by the proposed filter had a 15% average relative error over the entire wavelength range of interest., identifier:2435-0869

In this study, a dual-band hybrid filter that achieves high excitation light rejection performance in a lensless imaging system was fabricated and incorporated into an imaging device. The hybrid filter consisted of interference and absorption filters, and a fiber optic plate (FOP). The interference filters were attached to both sides of the FOP, which was placed on top of the absorption filter to suppress the decrease in spatial resolution. In addition, the lamination order was optimized to achieve a high fluorescence observation performance. The fabricated hybrid filter was mounted on an image sensor and had the ability to indicate the green and red fluorescence components., identifier:1347-4065

Various techniques for image color reproducibility under low-light conditions have been proposed, such as high sensitivity, a combination of visible (VIS) and infrared (IR) light, and coloring monochromatic images. However, when the illuminance falls below a certain level, color images cannot be obtained without prior color information. Previously, the exclusive use of IR without VIS illumination was proposed to achieve a pseudocolor image (basic IR color). It improved visibility compared with conventional monochrome images. However, there are cases, depending on the objects, when basic IR light cannot reproduce the correct color. An image processing method for enhancing color reproducibility is proposed, particularly for objects that are not suitable for the basic IR color (enhanced IR color). Moreover, we developed an algorithm to combine the advantages of both VIS and IR colors by utilizing signals of six wavelengths: three wavelengths each of VIS and IR. The proposed method includes an automatic transition between the optimal combination of VIS and IR colors when the illumination level changes, thus providing images with superior color reproducibility under various illumination levels compared with basic IR color., identifier:1560-2303