Biology subjects

Hirao, T.

Publications and source records attributed to Hirao, T..

5 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

Avoidance of simultaneous patch use in Japanese large-footed bats

Group foraging can enhance prey detection, but depending on resource availability, it may also generate conflicts among conspecifics. To understand how animals balance these benefits and costs, foraging performance must be evaluated together with inter-individual interactions. However, under fully natural conditions, it remains challenging to quantify both simultaneously. Here, we investigated how individual foraging efficiency and pairwise interactions are shaped when more than one individuals simultaneously exploit the same foraging patch, using the Japanese large-footed bat (Myotis macrodactylus) as a model system. We monitored an entire pond functioning as a natural foraging patch using two thermal cameras and an eight-channel microphone array, and reconstructed the arrival, prey-attack, and exit times of individual bats. Using a Poisson generalized linear mixed model (GLMM), we found that prey-attack rates were approximately 25% lower during paired flights than during solitary flights. We then constructed a null model in which arrival, attack, and departure events followed independent Poisson processes parameterized from the empirical data. Compared with null-model predictions, both the total duration and the duration of individual paired flights in the empirical data were significantly shorter, indicating that bats limited the time spent co-using the same patch relative to solitary foraging. In addition, the probability that the first exiting individual was the one that arrived earlier or later did not deviate from chance levels, providing no evidence for a prior residence advantage. Together, these results demonstrate that simultaneous patch use avoidance occurs independently of arrival order and coincides with reduced prey-attack rate, suggesting that bats leave shared patches and move to alternative foraging sites to mitigate losses in prey-attack efficiency. Our findings highlight bats as an excellent model system for non-invasively linking individual behavior and foraging performance via echolocation, and for elucidating the dynamics of foraging behavior and sensory interference in the wild.

animal behavior and cognition↗

bioRxiv2026

Chromosomal evolution and speciation inferred from chromosome-scale genome assemblies in three Cupressaceae species

Chromosome-scale genome assemblies in gymnosperms have lagged behind those of angiosperms, likely due to their large genomes. Coniferous tree species, which belong to the gymnosperms, are important resources for wood production in the forestry industry. To elucidate the evolution and speciation of these species and establish genome resources for breeding, we integrated draft assemblies with optical and genetic mapping to construct chromosome-scale genomes for Japanese cypress (Chamaecyparis obtusa, 8.7 Gb), Japanese cedar (Cryptomeria japonica, 9.6 Gb), and Chinese fir (Cunninghamia lanceolata, 13.4 Gb). Additionally, we assembled and annotated their chloroplast and mitochondrial genomes. Comparative analysis of the nuclear genomes revealed that while synteny is largely conserved, distinct translocations and inversions occurred in chromosomes 2, 6, and 9. Notably, the significantly larger genome of C. lanceolata was associated with frequent tandem gene duplications rather than transposon expansion. These findings suggest that chromosomal rearrangements and segmental duplications played key roles in the divergence of these species. The genomic resources presented here including chromosome-scale sequences, gene annotations, and genetic maps will facilitate advanced conifer genetics and accelerate forest tree breeding programs.

genomics↗

bioRxiv2024

A neuroimaging dataset during sequential color qualia similarity judgments with and without reports

Recent neuroscientific research has advanced our understanding of consciousness, yet the connection between specific qualitative aspects of consciousness, known as "qualia," and particular brain regions or networks remains elusive. Traditional methods that rely on verbal descriptions from participants pose challenges in neuroimaging studies. To address this, our group has introduced a novel "qualia structure" paradigm that leverages exhaustive, structural, and relational comparisons among qualia instead of verbal reports. In this study, we present the first fMRI dataset that captures relational similarity judgments among two out of nine color qualia per trial from 35 participants. This dataset also includes a "no-report" condition in half of the trials to assess the impact of overt reporting. Additionally, each participants color discriminability was evaluated with a hue test conducted outside the scanner. Our data offer valuable insights into the brain functions associated with color qualia and contribute to a deeper understanding of the neural foundations of consciousness.

neuroscience↗

bioRxiv2022

Haplotype-resolved de novo genome assemblies of four coniferous tree species

Coniferous trees in gymnosperm are an important source of wood production. Because of their long lifecycle, the breeding programs of coniferous tree are time- and labor-consuming. Genomics could accelerate the selection of superior trees or clones in the breeding programs; however, the genomes of coniferous trees are generally giant in size and exhibit high heterozygosity. Therefore, the generation of long contiguous genome assemblies of coniferous species has been difficult. In this study, we optimized the DNA library preparation protocols and employed high-fidelity (HiFi) long-read sequencing technology to sequence and assemble the genomes of four coniferous tree species, Larix kaempferi, Chamaecyparis obtusa, Cryptomeria japonica, and Cunninghamia lanceolata. Genome assemblies of the four species totaled 13.5 Gb (L. kaempferi), 8.5 Gb (C. obtusa), 9.2 Gb (C. japonica), and 11.7 Gb (C. lanceolata), which covered 99.6% of the estimated genome sizes on average. The contig N50 value, which indicates assembly contiguity, ranged from 1.2 Mb in C. obtusa to 16.0 Mb in L. kaempferi, and the assembled sequences contained, on average, 89.2% of the single-copy orthologs conserved in embryophytes. Assembled sequences representing alternative haplotypes covered 70.3-95.1% of the genomes, suggesting that the four coniferous tree genomes exhibit high heterozygosity levels. The genome sequence information obtained in this study represents a milestone in tree genetics and genomics, and will facilitate gene discovery, allele mining, phylogenetics, and evolutionary studies in coniferous trees, and accelerate forest tree breeding programs.

genomics↗