Publications by authors named "Yamashita O"

Sparse Bayesian learning has promoted many effective frameworks of brain activity decoding for the brain-computer interface, including the direct reconstruction of muscle activity using brain recordings. However, existing sparse Bayesian learning algorithms mainly use Gaussian distribution as error assumption in the reconstruction task, which is not necessarily the truth in the real-world application. On the other hand, brain recording is known to be highly noisy and contains many non-Gaussian noises, which could lead to large performance degradation for sparse Bayesian learning algorithms.

View Article and Find Full Text PDF
Article Synopsis
  • Autism spectrum disorder (ASD) is a complex lifelong condition, and this study aimed to create a classifier using resting-state fMRI from a large group of 730 Japanese adults to identify its neural and biological features.
  • The developed classifier showed effectiveness in differentiating individuals with ASD from neurotypical controls across various countries, including the US and Belgium, and it also applied to children and adolescents.
  • Importantly, the study found that the classifier identified crucial functional connections related to social interaction difficulties and neurotransmitter activity, and it linked ASD with similar neurobiological factors seen in ADHD and schizophrenia, enhancing understanding of related mental health disorders.
View Article and Find Full Text PDF
Article Synopsis
  • Neuroimaging databases for neuro-psychiatric disorders provide valuable data for researchers to explore diseases, develop machine learning models, and redefine understanding of these conditions.* ! -
  • A review identified 42 global MRI datasets totaling 23,293 samples from patients with various disorders, including mood, developmental, schizophrenia, Parkinson's, and dementia.* ! -
  • Improved governance and addressing technical issues of these databases are essential for sharing data across borders, aiding in understanding, diagnosing, and creating early interventions for neuro-psychiatric disorders.* !
View Article and Find Full Text PDF

Dynamic mode (DM) decomposition decomposes spatiotemporal signals into basic oscillatory components (DMs). DMs can improve the accuracy of neural decoding when used with the nonlinear Grassmann kernel, compared to conventional power features. However, such kernel-based machine learning algorithms have three limitations: large computational time preventing real-time application, incompatibility with non-kernel algorithms, and low interpretability.

View Article and Find Full Text PDF

Deep learning is a powerful tool for neural decoding, broadly applied to systems neuroscience and clinical studies. Interpretable and transparent models that can explain neural decoding for intended behaviors are crucial to identifying essential features of deep learning decoders in brain activity. In this study, we examine the performance of deep learning to classify mouse behavioral states from mesoscopic cortex-wide calcium imaging data.

View Article and Find Full Text PDF

Background: The World Health Organization has reported that approximately 300 million individuals suffer from the mood disorder known as MDD. Non-invasive measurement techniques have been utilized to reveal the mechanism of MDD, with rsfMRI being the predominant method. The previous functional connectivity and energy landscape studies have shown the difference in the coactivation patterns between MDD and HCs.

View Article and Find Full Text PDF

An optically pumped magnetometer (OPM) is a new generation of magnetoencephalography (MEG) devices that is small, light, and works at room temperature. Due to these characteristics, OPMs enable flexible and wearable MEG systems. On the other hand, if we have a limited number of OPM sensors, we need to carefully design their sensor arrays depending on our purposes and regions of interests (ROIs).

View Article and Find Full Text PDF
Article Synopsis
  • * A study involving 730 Japanese adults aimed to develop a generalizable neuromarker for ASD, successfully identifying relevant functional connections that differentiate individuals with ASD from typically developing controls (TDCs).
  • * The research found that the developed neuromarker is applicable across various age groups and countries, while also indicating a biological connection between ASD and schizophrenia (SCZ), but less so with major depressive disorder (MDD).
View Article and Find Full Text PDF

Purpose: This multicenter, prospective, observational study aimed to compare Zilver PTX and Eluvia stents in real-world settings for treating femoropopliteal lesions as the differences in the 1-year outcomes of these stents have not been elucidated.

Materials And Methods: Overall, 200 limbs with native femoropopliteal artery disease were treated with Zilver PTX (96 limbs) or Eluvia (104 limbs) at 8 Japanese hospitals between February 2019 and September 2020. The primary outcome measure of this study was primary patency at 12 months, defined as a peak systolic velocity ratio of ≤2.

View Article and Find Full Text PDF
Article Synopsis
  • - Recent advancements in sequential learning models like deep recurrent neural networks excel at creating task-specific representations for time series data, but struggle with generalizing across different tasks and can be too abstract for easy understanding.
  • - We introduce a unified local predictive model utilizing multi-task learning to generate task-agnostic and interpretable representations that can be applied across various temporal prediction tasks, making them easier for humans to comprehend.
  • - Our proof-of-concept results show that these new task-agnostic representations outperform traditional methods in temporal tasks and can also uncover the periodicity in time series data, with promising applications in analyzing fMRI data for better understanding of brain activity.
View Article and Find Full Text PDF
Article Synopsis
  • This technical report discusses the quality control status of iodine (I) seed source strength measurement for Permanent Prostate Brachytherapy in Japan, highlighting issues with traceability in source strength assessments.
  • A working group was formed by JASTRO in 2021 to tackle the challenges faced by medical facilities, including a lack of consistent source strength verification, with a survey revealing that 41% of facilities do not confirm the number of seeds or measure source strength.
  • The report emphasizes the importance of the single-seed assay as a reliable method for ensuring traceability, noting that most facilities in Japan do not utilize this standardized measurement technique.
View Article and Find Full Text PDF

Autism spectrum disorder (ASD) is a lifelong condition, and its underlying biological mechanisms remain elusive. The complexity of various factors, including inter-site and development-related differences, makes it challenging to develop generalizable neuroimaging-based biomarkers for ASD. This study used a large-scale, multi-site dataset of 730 Japanese adults to develop a generalizable neuromarker for ASD across independent sites (U.

View Article and Find Full Text PDF

Functional connectivity (FC) can provide insight into cortical circuit dysfunction in neuropsychiatric disorders. However, dynamic changes in FC related to locomotion with sensory feedback remain to be elucidated. To investigate FC dynamics in locomoting mice, we develop mesoscopic Ca imaging with a virtual reality (VR) environment.

View Article and Find Full Text PDF

Background And Hypothesis: Dynamics of the distributed sets of functionally synchronized brain regions, known as large-scale networks, are essential for the emotional state and cognitive processes. However, few studies were performed to elucidate the aberrant dynamics across the large-scale networks across multiple psychiatric disorders. In this paper, we aimed to investigate dynamic aspects of the aberrancy of the causal connections among the large-scale networks of the multiple psychiatric disorders.

View Article and Find Full Text PDF

Aim: Increasing evidence suggests that psychiatric disorders are linked to alterations in the mesocorticolimbic dopamine-related circuits. However, the common and disease-specific alterations remain to be examined in schizophrenia (SCZ), major depressive disorder (MDD), and autism spectrum disorder (ASD). Thus, this study aimed to examine common and disease-specific features related to mesocorticolimbic circuits.

View Article and Find Full Text PDF

Background: Recently, we developed a generalizable brain network marker for the diagnosis of major depressive disorder (MDD) across multiple imaging sites using resting-state functional magnetic resonance imaging. Here, we applied this brain network marker to newly acquired data to verify its test-retest reliability and anterograde generalization performance for new patients.

Methods: We tested the sensitivity and specificity of our brain network marker of MDD using data acquired from 43 new patients with MDD as well as new data from 33 healthy controls (HCs) who participated in our previous study.

View Article and Find Full Text PDF

Immunological aging is a critical event that causes serious functional impairment in the innate immune system. However, the identification markers and parameters are still poorly understood in immunological aging of myeloid lineage cells. Here, we show that a downregulation of lymphocyte antigen 6 complex locus G6D (Ly-6G) observed in aged mouse neutrophils could serve as a novel marker for the prediction of age-associated functional impairment in the neutrophils.

View Article and Find Full Text PDF

Phantom limb pain is attributed to abnormal sensorimotor cortical representations, although the causal relationship between phantom limb pain and sensorimotor cortical representations suffers from the potentially confounding effects of phantom hand movements. We developed neurofeedback training to change sensorimotor cortical representations without explicit phantom hand movements or hand-like visual feedback. We tested the feasibility of neurofeedback training in fourteen patients with phantom limb pain.

View Article and Find Full Text PDF

Diffuse optical tomography (DOT), as a functional near-infrared spectroscopy (fNIRS) technique, can estimate three-dimensional (3D) images of the functional hemodynamic response in brain volume from measured optical signals. In this study, we applied DOT algorithms to the fNIRS data recorded from the surface of macaque monkeys' skulls when the animals performed food retrieval tasks using either the left- or right-hand under head-free conditions. The hemodynamic response images, reconstructed by DOT with a high sampling rate and fine voxel size, demonstrated significant activations at the upper limb regions of the primary motor area in the central sulcus and premotor, and parietal areas contralateral to the hands used in the tasks.

View Article and Find Full Text PDF

Dynamic properties of resting-state functional connectivity (FC) provide rich information on brain-behavior relationships. Dynamic mode decomposition (DMD) has been used as a method to characterize FC dynamics. However, it remains unclear whether dynamic modes (DMs), spatial-temporal coherent patterns computed by DMD, provide information about individual behavioral differences.

View Article and Find Full Text PDF

Repetitive propagating activities in resting-state brain activities have been widely observed in various species and regions. Because they resemble the preceding brain activities during tasks, they are assumed to reflect past experiences embedded in neuronal circuits. "Whole-brain" propagating activities may also reflect a process that integrates information distributed over the entire brain, such as visual and motor information.

View Article and Find Full Text PDF

Recently, the dimensional approach has attracted much attention, bringing a paradigm shift to a continuum of understanding of different psychiatric disorders. In line with this new paradigm, we examined whether there was common functional connectivity related to various psychiatric disorders in an unsupervised manner without explicitly using diagnostic label information. To this end, we uniquely applied a newly developed network-based multiple clustering method to resting-state functional connectivity data, which allowed us to identify pairs of relevant brain subnetworks and subject cluster solutions accordingly.

View Article and Find Full Text PDF
Article Synopsis
  • Machine learning classifiers using resting-state fMRI are being used to explore the links between brain circuits and psychiatric disorders.
  • A large-scale database was created, including neuroimaging data from 993 patients and 1,421 healthy individuals, along with demographic details.
  • To ensure consistent data, nine healthy participants underwent brain imaging across 12 different scanners, and four datasets have been published for research use.
View Article and Find Full Text PDF

Multisite magnetic resonance imaging (MRI) is increasingly used in clinical research and development. Measurement biases-caused by site differences in scanner/image-acquisition protocols-negatively influence the reliability and reproducibility of image-analysis methods. Harmonization can reduce bias and improve the reproducibility of multisite datasets.

View Article and Find Full Text PDF

Large-scale neuroimaging data acquired and shared by multiple institutions are essential to advance neuroscientific understanding of pathophysiological mechanisms in psychiatric disorders, such as major depressive disorder (MDD). About 75% of studies that have applied machine learning technique to neuroimaging have been based on diagnoses by clinicians. However, an increasing number of studies have highlighted the difficulty in finding a clear association between existing clinical diagnostic categories and neurobiological abnormalities.

View Article and Find Full Text PDF