Biology subjects

Terasawa, Y.

Publications and source records attributed to Terasawa, Y..

6 recordsLinked to original sources

bioRxiv2026

Heartbeat-Related Bodily Processing Shapes Transition Patterns in Self-Related Spontaneous Thought

Spontaneous thought changes over time, yet the moment-to-moment factors shaping these changes remain poorly understood. We examined whether heartbeat-related bodily processing, operating largely outside explicit awareness, is associated with the organization of ongoing thought. Forty adults performed an auditory attention task with intermittent thought probes in which auditory events were scheduled either 200 ms after each detected R peak (synch condition) or independently of ongoing cardiac timing (asynch condition), with occasional omissions in both conditions. Heartbeat-synchronous omissions in this paradigm have been shown to induce cardiac deceleration and modulate heartbeat-evoked potentials (HEPs). The score of the heartbeat counting task (HCT) served as a behavioral index related to cardiac interoceptive accuracy. The results showed that higher HCT score was associated with a stronger synch-asynch shift toward more self-related and less task/self-unrelated thought. HEPs showed a synch-related negative shift across several thought groups, although the magnitude of this condition effect did not reliably differ among thought groups. Overall thought-group distributions were similar across conditions, while transition analyses suggested a tendency in the synch condition toward more frequent transitions linking predominantly interoceptive stimulus-dependent thought with both on-task and self-related thought. Together, these findings suggest that heartbeat-related bodily processing may influence the organization of spontaneous thought, particularly in individuals with greater cardiac interoceptive accuracy. Bodily signals may therefore act as an automatic constraint on the ongoing stream of thought, biasing which thought contents and transitions become more likely over time.

neuroscience↗

bioRxiv2026

Autonomic and cortical responses to heartbeat-synchronous auditory omissions during an auditory attention task

Cardiovascular regulation depends on bidirectional communication between autonomic cardiac control and cardiac afferent signals ascending to the central nervous system, forming a heart-brain loop. Cardio-auditory omission paradigms provide a non-invasive way to probe this loop in humans by withholding scheduled tones within heartbeat-contingent auditory sequences and measuring the resulting autonomic cardiac and heartbeat-related cortical responses. Previous studies have shown omission-evoked cardiac deceleration and neural responses mainly in specific contexts such as passive listening or synchrony-judgement tasks. The present study examined whether these responses also occur under the more general condition of active responses to external stimuli. We tested 40 adults in an auditory detection task in which tones were presented either 200 ms after the ECG R-peak (synch) or at pseudo-random intervals matched to each participants resting heart rate (asynch). A five-minute no-stimulation resting recording was used to generate the asynch sequence and served as the resting comparison condition. In both auditory conditions, 10% of scheduled tones were omitted, yielding synch and asynch omissions. Heartbeat-synchronous omissions induced sustained RR-interval prolongation that exceeded responses to asynch omissions, sound-present conditions, and rest. HEP amplitude was selectively enhanced in the synch-omission condition relative to all other conditions. Reaction times to the first post-omission tone were slightly delayed, whereas overall performance remained comparable across conditions. These findings show that heartbeat-synchronous auditory omissions produce a distinct autonomic-cortical response profile under active response demands, indicating that heart-brain loop dynamics continue to shape physiological responses during ongoing behaviour.

neuroscience↗

bioRxiv2025

Behavioural and physiological evidence for the development of cardiac-exteroceptive integration during the first year of life

Continuous integration of environmental exteroceptive and internal interoceptive signals is fundamental for perception and adaptive behaviours, yet its developmental trajectory remains poorly understood. Here, we introduced a modified iBEATs paradigm, based on prior work, to investigate cardiac-exteroceptive integration in 3-8-month-old infants. Using behavioural measures of looking time and physiological measures of pupillometry, we found that the ability to detect cardiac-exteroceptive synchrony emerges during the first year of life. Critically, this was evident only when stimuli coincided with systole, the baroreceptor-active phase of the cardiac cycle, supporting central multimodal integration interpretable within a predictive coding framework. Furthermore, individual differences in behavioural sensitivity were accounted for by the degree of autonomic maturation. These findings provide the first evidence for the developmental emergence and mechanisms of cardiac-exteroceptive integration, and establish the modified iBEATs paradigm as a promising tool for assessing interoceptive development in early life.

neuroscience↗

bioRxiv2024

Periplasmic serine protease Prc is responsible for amyloid subunit CsgA degradation and proteostasis in Escherichia coli

Escherichia coli synthesizes curli amyloid fibers extracellularly during biofilm formation and host colonization. The proteostasis network regulates the major curli subunit, CsgA, to prevent intracellular amyloid aggregation, yet the degradation mechanism remains elusive. Here, through a comprehensive investigation employing genetically engineered E. coli, multi-copy-suppressor screening, and biochemical analyses, we identify periplasmic serine protease Prc as a key player in CsgA degradation. Prc directly degrades CsgA through internal cleavage, differing from canonical tail-specific proteases. Although the bacterial HtrA homologs DegP and DegQ exhibit limited CsgA degradation activity in vitro in the presence of the suicide activator YjfN, deletion of these proteases did not affect native CsgA degradation in vivo. Instead, Prc, in coordination with the periplasmic chaperone CsgC, prevents the periplasmic accumulation of CsgA amyloid-like aggregates. Additionally, disruptions in secretion efficiency and proteolytic systems reduce csg operon expression through activation of the Rcs and Cpx two-component systems. These findings reveal a dual-layered strategy employed by E. coli to prevent intracellular accumulation of extracellular amyloids at both protein degradation and transcriptional regulation levels. This study provides insights into the mechanisms ensuring cellular homeostasis during curli biogenesis.

microbiology↗

bioRxiv2024

Brain-Body Interactions Influence the Transition from Mind Wandering to Awareness of Ongoing Thought

Our thoughts are inherently dynamic and often wander far from our current situation (mind wandering, MW). Although previous research revealed that the ascending arousal system shapes neural dynamics to mediate awareness of ongoing thoughts, the physiological states and afferent signals altered by this activation and its effects on awareness are unknown. In this study, we examined electroencephalography (EEG), electrocardiography (ECG), and respiration data before participants were aware of MW during a task in which they focused on external or internal stimuli. We showed that the transition from MW to awareness was characterized by decreased alpha and beta activity and increased heartbeat-evoked potential (HEP) amplitudes. In addition, the participants were more likely to be in the exhalation phase becoming aware, and in the inhalation phase at the time of MW reports. Moreover, changes in cardiac activity and HEP accompanied this pattern when participants were asked to focus on respiration. Based on these findings, we suggest that the release from the increased cognitive load with sustained MW and catching these changes as physiological alterations supporting awareness of MW; moreover, the modulation of the respiratory cycle by focusing on breathing enhances these changes.

neuroscience↗

bioRxiv2024

The Body Mirroring Thought: The Relationship Between Thought Transitions and Fluctuations in Autonomic Nervous Activity Mediated by Interoception

Our thought states change unconsciously. This study verified that the transference of thought states varies with fluctuations in autonomic nervous activity, and that this effect is modulated by interoceptive accuracy. The participants completed the heartbeat counting task (HCT) and vigilance task (VT). We assessed the participants interoceptive accuracy based on their performance on the HCT. The VT is a simple attention task, and during this task, we asked the participants to report the content and contemplation of their thoughts. Consequently, participants with accurate interoception were more likely to remain in a highly contemplative thought state when sympathetic activity was activated. In contrast, the dominance of parasympathetic activity facilitated transitions to different thought states or experiences of less contemplative thought states in them. The results suggest that even subtle changes in bodily responses at rest can affect thought transitions in people with accurate interoception.

neuroscience↗