Biology subjects

Terada, K.

Publications and source records attributed to Terada, K..

3 recordsLinked to original sources

bioRxiv2026

Resting-state heartbeat-evoked potentials are associated with Kalman-derived cardiac prediction errors

The heartbeat-evoked potential (HEP) reflects the cortical processing of cardiac afferent signals. However, it remains unclear whether trial-level interoceptive prediction errors can be quantified directly from spontaneous resting cardiac fluctuations and whether these model-derived errors are associated with HEP amplitude. Here, we applied a Kalman filter, implemented as a sequential Bayesian estimation procedure, to resting-state EEG and ECG recordings from 21 healthy adults to estimate trial-by-trial signed prediction errors in RR-intervals. Positive prediction errors reflected unexpected cardiac deceleration, whereas negative prediction errors reflected unexpected cardiac acceleration. Cluster-based permutation tests showed that unexpected cardiac acceleration was associated with greater fronto-centro-parietal HEP amplitude than unexpected deceleration in an early post-R-peak window, spanning FC1, CP1, Pz, CP2, Cz, C4 and FC2 from 215 to 250 ms. A Bayesian linear mixed-effects model further indicated a credible negative association between signed prediction error and HEP amplitude after controlling for respiratory phase and preceding RR interval. In a secondary connectivity analysis, unexpected acceleration was associated with stronger Cz-to-frontal beta-band phase synchrony during a later post-R-peak window from 250 to 500 ms. Exploratory individual-difference analyses suggested that neuroticism was negatively correlated with late frontal HEP amplitude during unexpected acceleration, but not during unexpected deceleration or when trials were pooled across conditions. These findings demonstrate that spontaneous cardiac fluctuations can be used to derive trial-level computational estimates of interoceptive prediction error and that these estimates are reflected in early HEP amplitude. They further suggest that the cortical processing of unexpected cardiac acceleration may be related to individual differences in affective personality traits.

neuroscience↗

bioRxiv2026

Elasticity of a three-dimensional cell vertex model of epithelia

Material properties of epithelial tissues play essential roles in morphogenesis and physiological function, yet how tissue-scale viscoelasticity emerges from cellular-scale mechanics remains unclear. Here, we investigate the elastic mechanics of a three-dimensional cell vertex model for epithelial monolayers. By analyzing infinitesimal affine deformations around a regular hexagonal-prism equilibrium state, we derive analytical expressions for the in-plane elastic moduli. We show that the model produces a near-zero in-plane Poissons ratio over a broad region of parameter space, thereby accounting for a characteristic mechanical property reported in cultured epithelial monolayers. Numerical simulations further confirm that the theoretical Poissons ratio remains accurate under finite, biologically relevant strains. In addition, we show that the morphological bistability between squamous-like and columnar-like states is associated with distinct elastic responses. Our results indicate that three-dimensional vertex models can account not only for epithelial morphogenesis but also for their material properties.

biophysics↗

bioRxiv2026

Thermal Conductivity of Artificial Materials Engineered from Plant and Bacterial Cells

Bio-based materials are known for their excellent biodegradability and, in some cases, their potential to fix carbon dioxide. Owing to these properties, they are increasingly being utilized as environmentally friendly alternatives across various applications. In this study, we focused on using living cells themselves as material components, aiming to evaluate their potential as substitutes for conventional plastic-based thermal insulators. We selected two types of cells, photosynthetic purple non-sulfur bacterium Rhodovulum sulfidophilum and tobacco BY-2 plant suspension cells. After optimizing solidification conditions through the addition of pectin and cellulose nanofibers, we measured the thermal conductivity of the solidified cells under atmospheric pressure. The results showed that R. sulfidophilum exhibited 0.0553 W/m{middle dot}K, while BY-2 exhibited a thermal conductivity of 0.043 W/m{middle dot}K. Both values indicate relatively low thermal conductivity compared to existing bio-based materials, suggesting high insulation performance. Among the solidified cells, the solidified BY-2 cells showed minimal variation in thermal insulation performance under pressure changes, and had a low thermal emissivity as revealed by FT-IR analysis. Based on these findings, we propose that cell-derived materials can serve as potentially biodegradable bio-based thermal insulation materials.

bioengineering↗