Biology subjects

Agetsuma, M.

Publications and source records attributed to Agetsuma, M..

5 recordsLinked to original sources

bioRxiv2026

In vivo brain temperature measurement using quantum dot imaging temperature sensors

Temperature regulation in the brain is essential for maintaining neuronal function and preventing thermally induced damage. Here, we report the development and in vivo application of quantum dots (QDs) to high-resolution thermometry in the mouse brain using two-photon excitation microscopy. These QDs, via the red-to-green photoluminescence (PL) intensity ratios, enabled stable temperature measurements in both normal and chronically hypo-perfused cerebral tissue. Our findings show that localized neuronal activity leads to transient heat generation, which is rapidly dissipated by cerebrovascular responses. In a chronic hypoperfusion model, impaired vascular function resulted in exaggerated and prolonged brain temperature elevations. This thermometry system provides unprecedented insight into the mechanisms of cerebral thermoregulation and highlights the importance of vascular cooling in protecting the brain from heat-induced stress, particularly in pathological conditions such as stroke.

bioengineering↗

bioRxiv2025

In vivo deep-brain microscopy at submicrometer resolution with refractive index-matched prism interfaces

The mammalian brain is a thick and densely layered structure comprising a huge number of neurons that work together to process information and regulate brain functions. Although various optical methods have been developed to investigate deep brain dynamics, they are limited by technical constraints, invasiveness, suboptimal spatial resolution, and/or a restricted field of view. To overcome these limitations, we developed an implantable, optically optimized microprism interface with a refractive index matched to that of brain tissue and water, enabling minimally-invasive, wide-field two-photon imaging method with enhanced brightness and sub-micron resolution in deep prefrontal areas.

neuroscience↗

bioRxiv2024

Low-invasive, wide-field, and cellular resolution two-photon imaging of neural population activity in brainstem and nucleus tractus solitarii

Brain-viscera communication plays a crucial role in regulating mental health, with the vagus nerve being a key structure mediating this interaction. Clinically, artificial vagus nerve stimulation (VNS) is used to treat various neuropsychiatric disorders, highlighting the importance of vagal afferent fibers in regulating emotion. The nucleus tractus solitarii (NTS) is a brainstem structure proposed to receive signals from vagal afferents and relay them to brain networks for emotion regulation. However, due to the anatomical complexity and difficulty in accessing the deep-brain NTS region in living animals, the mechanisms remain unclear. Here, we developed a wide-field and deep-brain two-photon imaging method using a double-prism based optical interface. This approach enables the identification of cellular-resolution neural activities in the NTS while preserving the cerebellum, which covers the NTS and is important for emotion regulation, intact. We systematically evaluated how NTS neurons respond to VNS and a gastrointestinal hormone, suggesting the usefulness of this method for investigating the role of the vagus-NTS pathway in vivo.

neuroscience↗

bioRxiv2021

Optical and computational dissection of emergent prefrontal rewiring to encode fear memory

Associative learning is crucial for adapting to environmental changes. The encoding of associative learning involves the dorso-medial prefrontal cortex (dmPFC), and is underpinned by interactions within the resident neuronal population. However, the nature of this population coding is poorly understood. Here we developed a pipeline for computational dissection and longitudinal two-photon imaging of neural population activities in the mouse dmPFC during fear-conditioning procedures, enabling us to detect learning-dependent changes in the dmPFC topology. Through regularized regression methods and graphical modeling, we found fear conditioning organized neuronal ensembles encoding conditioned responses (CR), with enhancing their coactivity, functional connectivity, and association with conditioned stimuli (CS). This suggests that fear conditioning drives dmPFC reorganization to generate novel associative circuits for CS-to-CR transformation. Importantly, neurons strongly responding to unconditioned stimuli (US) during conditioning anterogradely became a hub of the CR ensemble. Altogether, we demonstrate learning-dependent dynamic modulation of population coding structured on an activity-dependent hub-network formation within the dmPFC. TeaserOptical and computational dissection uncovered how prefrontal cortical networks are rewired to encode new associative memory Significance statementAnimals learn to adapt to changing environments. Associative learning is one of the simplest types of learning that has been intensively studied over the past century. Recent development in molecular, genetic, and optogenetic methods has enabled the identification of a neural population encoding the associative memory in the brain. However, it remains unclear how information is stored and processed by the neural population to encode and retrieve the associative memory. To investigate the nature of this population coding, we developed an optical and computational dissection method, demonstrating how associative learning drives reorganization of the neural network in the dorso-medial prefrontal cortex and generates novel circuits for associative memory and signal transformation.

neuroscience↗

bioRxiv2017

In vivo brain activity imaging of interactively locomoting mice

Electrophysiological field potential dynamics have been widely used to investigate brain functions and related psychiatric disorders. Conversely, however, various technical limitations of conventional recording methods have limited its applicability to freely moving subjects, especially when they are in a group and socially interacting with each other. Here, we propose a new method to overcome these technical limitations by introducing a bioluminescent voltage indicator called LOTUS-V. Using our simple and fiber-free recording method, named \"SNIPA,\" we succeeded in capturing brain activity in freely-locomotive mice, without the need for complicated instruments. This novel method further allowed us to simultaneously record from multiple independently-locomotive animals that were interacting with one another. Further, we successfully demonstrated that the primary visual cortex was activated during the interaction. This methodology will further facilitate a wide range of studies in neurobiology and psychiatry.

neuroscience↗