Biology subjects

Nozawa, T.

Publications and source records attributed to Nozawa, T..

3 recordsLinked to original sources

bioRxiv2026

Improving Emotion Classification by Combining fNIRS-Derived Hemodynamic Responses with Peripheral Physiological Signals

We investigated whether multimodal sensing that combines functional near-infrared spectroscopy (fNIRS) with peripheral physiological signals can improve subject-independent classification of arousal and valence, the fundamental affective dimensions in Russells circumplex model. We developed Japanese emotion-inducing music-video stimuli (60 seconds each) and recorded subjects central nervous system activity using fNIRS, alongside peripheral physiological measures, specifically electrodermal activity (EDA) and photoplethysmography (PPG), during video viewing. To prioritize reproducibility and methodological transparency, we extracted simple, easily computed features from each modality and performed binary (high vs. low) classification separately for arousal and valence using a support vector machine. The combination of fNIRS and EDA yielded the highest performance, with a macro-averaged F1 score of 0.73 for arousal and 0.64 for valence. These findings underscore the utility of integrating fNIRS with peripheral physiological signals for subject-independent emotion classification.

neuroscience↗

bioRxiv2020

Intracellular Group A Streptococcus induces Golgi fragmentation to impair host defenses through Streptolysin O and NAD-glycohydrolase

Group A Streptococcus (GAS; Streptococcus pyogenes) is a major human pathogen that causes streptococcal pharyngitis, skin and soft-tissue infections, and life-threatening conditions such as streptococcal toxic-shock syndrome. During infection, GAS not only invades diverse host cells, but also injects effector proteins such as NAD-glycohydrolase (Nga) into the host cells through a streptolysin O (SLO)-dependent mechanism without invading the cells; Nga and SLO are two major virulence factors that are associated with increased bacterial virulence. Here, we have shown that the invading GAS induces fragmentation of the Golgi complex and inhibits anterograde transport in the infected host cells through the secreted toxins SLO and Nga. GAS infection-induced Golgi fragmentation required both bacterial invasion and SLO-mediated Nga translocation into the host cytosol. The cellular Golgi network is critical for the sorting of surface molecules and thus is essential for epithelial barrier integrity and the immune response of macrophages to pathogens. In epithelial cells, inhibition of anterograde trafficking by invading GAS and Nga resulted in the redistribution of E-cadherin to the cytosol and an increase in bacterial translocation across the epithelial barrier. Moreover, in macrophages, interleukin-8 secretion in response to GAS infection was found to be suppressed by intracellular GAS and Nga. Our findings reveal a previously undescribed bacterial invasion-dependent function of Nga as well as a previously unrecognized GAS-host interaction that is associated GAS pathogenesis. ImportanceTwo prominent virulence factors of GAS, SLO and Nga, have been established to be linked to enhanced pathogenicity of prevalent GAS strains. Recent advances show that SLO and Nga are important for intracellular survival of GAS in epithelial cells and macrophages. Here, we found that invading GAS disrupt the Golgi complex in host cells by SLO and Nga. We showed that GAS-induced Golgi fragmentation requires bacterial invasion into host cells, SLO pore-formation activity, and Nga NADase activity. GAS-induced Golgi fragmentation resulted in the impairment of epithelial barrier and chemokine secretion in macrophages. This immune inhibition property of SLO and Nga by intracellular GAS indicates that the invasion of GAS is associated with virulence exerted by SLO and Nga.

microbiology↗

bioRxiv2019

Prior physical synchrony enhances rapport and inter-brain synchronization during subsequent educational communication

Physical synchrony has been suggested to have positive effects on not only concurrent but also subsequent communication, but the underlying neural processes are unclear. Using functional near-infrared spectroscopy (fNIRS) hyperscanning, we tested the effects of preceding physical synchrony on subsequent dyadic teaching-learning communication. Thirty-two pairs of participants performed two experimental sessions. In each session, they underwent a rhythmic arm movement block with synchronous or asynchronous conditions, and then taught/learned unknown words to/from each other according to a given scenario. Neural activities in their medial and left lateral prefrontal cortex (PFC) were measured and inter-brain synchronization (IBS) during the teaching-learning blocks was evaluated. Participants rated their subjective rapport during the teaching-learning blocks, and took a word memory test. The analyses revealed that (1) prior physical synchrony enhanced teacher-learner rapport; (2) prior physical synchrony also enhanced IBS in the lateral PFC; and (3) IBS changes correlated positively with rapport changes. Physical synchrony did however not affect word memory performance. These results suggest that IBS can be useful to measure the effects of social-bonding facilitation activities for educational communication.

neuroscience↗