Biology subjects

Nishiyama, Y.

Publications and source records attributed to Nishiyama, Y..

9 recordsLinked to original sources

bioRxiv2023

Robust spatial self-organization in crowds of asynchronous pedestrians

Similar to other animal groups, human crowds exhibit a variety of self-organized collective behaviors. Spontaneous formation of unidirectional lanes in bidirectional pedestrian flows is one of the most striking examples of self-organization in human crowds. In addition, previous experimental studies have suggested that stepping among pedestrians is spontaneously synchronized over time. However, those studies have primarily focused on one-dimensional, single-file crowds, limiting our understanding of temporal stepping patterns in crowds with more freedom of movement and their relationship to spatial patterns of organization. Here, we conducted experiments of bidirectional pedestrian flows (24 pedestrians in each group) and investigated the relationship between collective footsteps and self-organized lane formation by tracking each individual trajectory as well as foot-stepping kinematics. We found that, unlike previous studies, pedestrians did not spontaneously align their steps unless there was an external auditory cue to follow. Moreover, we found that footstep synchronization generated by external cues disturbed the flexibility of pedestrians lateral movements, increased potential collision risks, and narrowed the formed lanes, suggesting structural instability in the spatial organization. These results imply that, without external cues, pedestrians marching out of step with each other can efficiently self-organize into robust structures. Understanding how asynchronous individuals contribute to ordered collective behavior has potential applications for promoting efficient crowd management and will inform theoretical models for human and other animal collective behavior with asynchronous positional updates.

animal behavior and cognition↗

bioRxiv2023

Cell wall pectic β-1,4-galactan contributes to increased plant freezing tolerance induced by cold acclimation

Subzero temperatures are often lethal to plants. Many temperate plants have a mechanism called cold acclimation that allows them to sense a drop in temperature and prepare for freezing stress through accumulation of soluble sugars and cryoprotective proteins. Plant cells are surrounded by a cell wall and as ice formation primarily occurs in the extracellular matrix (the apoplast), cell wall properties are important for plant freezing tolerance. Although previous studies have shown that the amounts of constituent sugars of the cell wall, in particular those present in pectic polysaccharides, are altered by cold acclimation, the significance of this change during cold acclimation has not been clarified. We found that {beta}-1,4-galactan, which forms neutral side chains of pectin, accumulates in the cell walls of Arabidopsis and various freezing tolerant vegetables during cold acclimation. The gals1 gals2 gals3 triple mutant, which has reduced {beta}-1,4-galactan in the cell wall, exhibited reduced freezing tolerance compared with wild-type Arabidopsis during initial stages of cold acclimation. Expression of genes involved in the galactan biosynthesis pathway such as GALACTAN SYNTHASES and UDP-glucose 4-epimerases were induced during cold acclimation in Arabidopsis explaining galactan accumulation. Cold acclimation resulted in a decrease in extensibility and an increase in rigidity of the cell wall in the wild type, whereas these changes were not observed in the gals1 gals2 gals3 triple mutant. These results indicate that the accumulation of pectic {beta}-1,4-galactan contributes to acquired freezing tolerance by cold acclimation via changes in cell wall mechanical properties.

plant biology↗

bioRxiv2023

Characterization and Applications of Evoked Responses During Epidural Electrical Stimulation

Epidural electrical stimulation (EES) of the spinal cord has been FDA approved and used therapeutically for decades. However, there is still not a clear understanding of the local neural substrates and consequently the mechanism of action responsible for the therapeutic effects. Epidural spinal recordings (ESR) are collected from the electrodes placed in the epidural space. ESR contains multi-modality signal components such as the evoked neural response (due to tonic or BurstDR waveforms), evoked muscle response, stimulation artifact, and cardiac response. The tonic stimulation evoked compound action potential (ECAP) is one of the components in ESR and has been proposed recently to measure local neural activation during EES. Here, we first review and investigate the referencing strategies, as they apply to ECAP component in ESR in the domestic swine animal model. We then examine how ECAP component can be used to sense lead migration, an adverse outcome following lead placement that can reduce therapeutic efficacy. Lastly, we show and isolate concurrent activation of local back and leg muscles during EES, demonstrating that the ESR obtained from the recording contacts contain both ECAP and EMG components. These findings may further guide the implementation of recording and reference contacts in an implantable EES system and provide preliminary evidence for the utility of ECAP component in ESR to detect lead migration. We expect these results to facilitate future development of EES methodology and implementation of use of different components in ESR to improve EES therapy.

physiology↗

bioRxiv2022

Spontaneous behavioral coordination between pedestrians emerges through mutual anticipation rather than mutual gaze

Human activities are often performed together between two or more persons, as if they are a complex dance. Threading through a crowd is a striking example of such coordinated actions. Behavioral coordination should help to reduce head-on collisions, smooth a pedestrians pathway through a crowd, and promote a self-organization process. Although mutual anticipation between pedestrians would be a candidate for underlying mechanisms of behavioral coordination, it remains largely unexplored, especially in terms of visual information. Here, we investigated the effects of mutual anticipation between a pair of pedestrians performing simple avoidance tasks using a combination of motion- and eye-tracking systems. We found that pedestrians in a baseline condition spontaneously coordinated their walking speed and angle until passing each other. Visually distracting one of the pedestrians decreased the level of behavioral coordination, indicating that spontaneous coordination emerges through mutual anticipation. Importantly, blocking the pedestrians gaze information alone did not alter their walking, clearly ruling out the assumption that mutual gaze impacts pedestrian anticipation behavior. Moreover, eye-movement analysis demonstrated that the direction of a pedestrians gaze changed depending on the uncertainty of the oncoming pedestrians motion and that pedestrians tend to look ahead toward the ultimate passing direction before they actually walked in that direction. We propose that body motion cues may be sufficient and available for implicit negotiation on potential future motions. Our findings should be useful in various fields, including research on improvisational motions, pedestrian transportation, and robotic navigation.

animal behavior and cognition↗

bioRxiv2021

Ambiguous Body Ownership Experience Caused by Feeling-judgement Conflict: Evidence from Subjective Measurement in Rubber Hand Illusion using Integrated Information Theory

AO_SCPLOWBSTRACTC_SCPLOWHuman body awareness is malleable and adaptive to changing contexts. The illusory sense of body-ownership has been studied since the publication of the rubber hand illusion, where ambiguous body ownership feeling, expressed as "the dummy hand is my hand even though that is not true", was first defined. Phenomenologically, the ambiguous body ownership is attributed to a conflict between feeling and judgement; in other words, it characterises a discrepancy between first-person (i.e. bottom-up) and third-person (i.e. top-down) processes. Although Bayesian inference can explain this malleability of body image sufficiently, the theory does not provide a good illustration of why we have different experiences to the same stimuli - the difficulty lies in the uncertainty regarding the concept of judgement in their theory. This study attempts to explain subjective experience during rubber hand illusions using integrated information theory (IIT). The integrated information {Phi} in IIT measures the difference between the entire system and its subsystems. This concept agrees with the phenomenological interpretation - that is, there is conflict between judgement and feeling. By analysing the seven nodes of a small body- brain system, we demonstrate that the integrity of the entire system during the illusion decreases with increasing integrity of its subsystems. These general tendencies agree well with many brain-image analyses and subjective reports; furthermore, we found that subjective ratings were associated with the {Phi}s. Our result suggests that IIT can explain the general tendency of the sense of ownership illusions and individual differences in subjective experience during the illusions.

animal behavior and cognition↗

bioRxiv2021

Protein resonance assignment by solid-state NMR based on 1H-detected 13C-based double-quantum spectroscopy at fast MAS

Solid-state NMR spectroscopy is a powerful technique to study insoluble and non-crystalline proteins and protein complexes at atomic resolution. The development of proton (1H) detection at fast magic-angle spinning (MAS) has considerably increased the analytical capabilities of the technique, enabling the acquisition of 1H-detected fingerprint experiments in few hours. Here an approach based on double-quantum (DQ) 13C spectroscopy, detected on 1H, is introduced at fast MAS (70 kHz) to perform the sequential assignment of insoluble proteins of small size, without any specific deuteration requirement. By combining two three-dimensional 1H detected experiments correlating a 13C DQ dimension respectively to its intra-residue and sequential 15N-1H pairs, a sequential walk through DQ (C+CO) resonance is obtained. Our approach takes advantage of fast MAS to achieve an efficient sensitivity and the addition of a DQ dimension provides spectral features useful for the resonance assignment process.

biophysics↗

bioRxiv2020

Mutual anticipation can contribute to self-organization in human crowds

Human crowds provide paradigmatic examples of collective behavior emerging through self-organization. Although the underlying interaction has been considered to obey the distance-dependent law, resembling physical particle systems, recent findings emphasized that pedestrian motions are fundamentally influenced by the anticipated future positions of their neighbors rather than their current positions. Therefore, anticipatory interaction may play a crucial role in collective patterning. However, whether and how individual anticipation functionally benefits the group is not well-understood. We suggest that collective patterning in human crowds is promoted by anticipatory path-seeking behavior resulting in a scale-free movement pattern, called the Levy walk. In our experiments of lane formation, a striking example of self-organized patterning in human crowds where people moving in opposite directions spontaneously segregate into several unidirectional lanes, we manipulated some pedestrians ability to anticipate by having them type on a mobile phone while walking. The manipulation slowed overall walking speeds and delayed the onset of global patterning, and the distracted pedestrians sometimes failed to achieve their usual walking strategy. Moreover, we observed that the delay of global patterning depends on decisions made by pedestrians who were moving toward the distracted ones and had no choice but to take sudden large steps, presumably because of difficulty in anticipating the motions of their counterparts. These results imply that mutual anticipation between pedestrians facilitates efficient transition to emergent patterning in situations where nobody within a crowd is distracted. Our findings may contribute to efficient crowd management and inform future models of self-organizing systems.

animal behavior and cognition↗

bioRxiv2020

Neural correlates of temporal presentness in theprecuneus: a crosslinguistic fMRI study based on speech stimuli

AbstractsThe position of any event in time could be either present, past, or future. This temporal discrimination is vitally important in our daily conversations, but it remains elusive how the human brain distinguishes among the past, present, and future. To address this issue, we searched for neural correlates of presentness, pastness, and futurity, each of which is automatically evoked when we hear sentences such as it is raining now, it rained yesterday, or it will rain tomorrow. Here, we show that sentences that evoked presentness activated the bilateral precuneus more strongly than those that evoked pastness or futurity. Interestingly, this contrast was shared across native speakers of Japanese, English, and Chinese, languages which vary considerably in their verb tense systems. The results suggest that the precuneus serves as a key region that provides the origin, the Now, to our time perception irrespective of differences in tense systems across languages.

neuroscience↗

bioRxiv2019

Exploiting Heterogeneous Time Scale of Dynamics toEnhance 2D HETCOR Solid-State NMR Sensitivity

Multidimensional solid-state NMR spectroscopy plays a significant role in offering atomic-level insights into molecular systems. In particular, heteronuclear chemical shift correlation (HETCOR) experiments could provide local chemical and structural information in terms of spatial heteronuclear proximity and through-bond connectivity. In solid state, the transfer of magnetization between heteronuclei, a key step in HETCOR experiments, is usually achieved using cross-polarization (CP) or INEPT (insensitive nuclei enhanced by polarization transfer) depending on the sample characteristics and magic-angle-spinning (MAS) frequency. But, for a multiphase system constituting molecular components that differ in their time scales of mobilities, CP efficiency is pretty low for mobile components because of the averaging of heteronuclear dipolar couplings whereas INEPT is inefficient due to the short T2 of immobile components and can be non-selective due to strong proton spin diffusion for immobile components especially under moderate spinning speeds. Herein, in this study we present two 2D pulse sequences that enable the sequential acquisition of 13C/1H HETCOR NMR spectra for the rigid and mobile components by taking full advantage of the abundant proton magnetization in a single experiment with barely increasing the overall experimental time. In particular, the 13C-detected HETCOR experiment could be applied under slow MAS conditions, where a multiple-pulse sequence is typically employed to enhance 1H spectral resolution in the indirect dimension. In contrast, the 1H-detected HETCOR experiment should be applied under ultrafast MAS, where CP and transient heteronuclear nuclear Overhauser effect (NOE) polarization transfer are combined to enhance 13C signal intensities for mobile components. These pulse sequences are experimentally demonstrated on two model systems to obtain 2D 13C/1H chemical shift correlation spectra of rigid and mobile components independently and separately. These pulse sequences can be used for dynamics difference based spectral editing and resonance assignments. Therefore, we believe the proposed 2D HETCOR NMR pulse sequences will be beneficial for the structural studies of heterogeneous systems containing molecular components that differ in their time scale of motions for understanding the interplay of structures and properties.

bioengineering↗