Biology subjects

Ishijima, A.

Publications and source records attributed to Ishijima, A..

4 recordsLinked to original sources

bioRxiv2026

Light Guiding in Scattering Media Using Focused Laser-Induced Acoustic Waves with an Open Elliptical Reflector

Light scattering in biological tissue limits deep optical imaging. Acoustic waves can modulate optical properties and enhance photon delivery, but source-positioning requirements can complicate integration with other imaging modalities. Here, we present an open elliptical reflector that focuses laser-induced acoustic waves at a spatially separated target while maintaining open optical access. We characterized the spatiotemporal optical modulation induced by the localized acoustic focus. The system increased the local transmitted-light intensity by a factor of 2.57-fold through a 2-mm-thick 1% intralipid hydrogel and enhanced fluorescence signal under two-photon excitation through a 1.5-mm-thick scattering sample. These results demonstrate spatially separated, reflector-based acoustically assisted light guiding for enhanced light delivery and fluorescence excitation through scattering media.

bioengineering↗

bioRxiv2026

Image-scanning light-sheet microscopy for high-speed volumetric imaging of complex biological dynamics

Volumetric fluorescence microscopy is a powerful method for studying complex biological systems because it enables comprehensive observation of structural and physiological dynamics. In particular, light-sheet microscopy (LSM) is a leading option for real-time volumetric fluorescence imaging as it combines high imaging speed, low phototoxicity, minimal photobleaching, high spatiotemporal resolution, and low computational burden. To capture fast biological events, various efforts have been made to improve the imaging speed of volumetric fluorescence microscopy, including LSM. However, existing approaches entail significant trade-offs that make routine volumetric imaging at and beyond video rates challenging under practical conditions. Here, we introduce image-scanning LSM, a method that substantially increases the volumetric imaging speed achievable with LSM while preserving key performance metrics, such as spatial resolution and photon efficiency, as well as accessibility. Our implementation, termed image-scanning oblique plane (ISOP) microscopy, enables volumetric fluorescence imaging at up to 1,000 volumes per second with submicrometer lateral spatial resolution. We demonstrate the broad utility of ISOP microscopy by recording and analyzing the dynamics of behaving and rapidly moving organisms.

bioengineering↗

bioRxiv2021

Acoustic frequency-dependent physical mechanism of sub-MHz ultrasound neurostimulation

Ultrasound is an innovative physical modality allowing non-invasive and reversible modulation of neural circuit activity in the brain with high spatial resolution. Despite growing interest in clinical applications, the safe and effective use of ultrasound neuromodulation has been limited by a lack of understanding of the physical mechanisms underlying its effects. Here, we demonstrate acoustic frequency-dependent physical effects that underlie ultrasound neuromodulation, where cavitation and radiation forces are the dominant sources of low- and high-frequency stimulation, respectively. We used 39.5 kHz and 500 kHz acoustic frequencies to stimulate cultured neural and glial cells, excised from rat cortex, to study acoustic frequency-dependent neural responses. We demonstrate increased evoked responses due to increased cavitation activity at the 39.5 kHz acoustic frequency. In contrast, notable cavitation activity was not detected at 500 kHz despite detection of evoked responses. Our work highlights the dependence of ultrasound neuromodulation on acoustic frequencies, with different physical effects underlying cell responses to low and high sub-MHz acoustic frequency ranges.

bioengineering↗

bioRxiv2021

Acoustic light-sheet microscopy

Light-sheet imaging of 3D objects with high spatial resolution remains an open challenge because of the trade-off between field-of-view (FOV) and axial resolution originating from the diffraction of light. We developed acoustic light-sheet microscopy (acoustic LSM), which actively manipulates the light propagation inside a large sample to obtain wide-field microscopic images deep inside a target. By accurately coupling a light-sheet illumination pulse into a planar acoustic pulse, the light-sheet can be continuously guided over large distances. We imaged a fluorescence-labeled transparent mouse brain for the FOVs of 19.3 x 12.4 mm2 and 9.7 x 5.9 mm2 with resolved microstructures and single cells deep inside the brain. Acoustic LSM creates new opportunities for the application of light-sheet in the field of industry to basic science. One Sentence SummaryAn acoustic-optical method overcomes a trade-off between field-of-view and axial resolution in light-sheet microscopy.

bioengineering↗