Biology subjects

Zaccaro, A.

Publications and source records attributed to Zaccaro, A..

7 recordsLinked to original sources

bioRxiv2025

Breathing strategies to influence perception: Evidence for interoceptive and exteroceptive active sensing

Recent research indicates that humans continuously and automatically modulate their breathing to temporally align exteroceptive stimuli with specific phases of the respiratory cycle. This process has been interpreted as a form of active sensing and is associated with faster responses and improved perceptual accuracy. While converging evidence suggests that respiration also shapes interoceptive processing at both neural and behavioural levels, it remains unclear whether individuals actively adjust their breathing to optimize interoceptive performance. In this study, we examined whether healthy participants modulated their respiration during an interoceptive (heartbeat discrimination) and an exteroceptive (tactile detection) task. We analysed respiration both in terms of time-locked activity and inter-trial phase coherence relative to stimulus onset and assessed their relationship with perceptual accuracy. Our results demonstrated that participants systematically adjust their breathing in both amplitude and phase, synchronizing respiration to the anticipated (i.e., cued) onset of stimuli in both tasks. Crucially, task performance was enhanced during exhalation compared to inhalation, suggesting that respiratory modulation supports the perception of both interoceptive and exteroceptive signals. Significance statementThis study reveals that humans not only synchronize their breathing to anticipated external and internal stimuli, but also perform better when perceiving them during exhalation. By showing that respiration is modulated in both interoceptive and exteroceptive contexts, our findings extend the concept of active sensing to internal bodily awareness. This has important implications for understanding the dynamic interplay between physiology and perception and may guide interventions aimed at improving clinical outcomes in conditions where interoception is disrupted.

neuroscience↗

bioRxiv2025

Cardio-respiratory interactions in interoceptive perception: The role of heartbeat-modulated cortical oscillations

The cardiovascular and respiratory systems are anatomically and functionally integrated within the cardio-respiratory system. This close connection suggests that breathing continuously shapes cardiac interoceptive perception. Previously, we demonstrated cardio-respiratory interoceptive interactions in the heartbeat-evoked potential, a neural marker of cortical processing of cardiac signals. Specifically, we observed enhanced late heartbeat-evoked potential positivity and greater interoceptive accuracy during exhalation compared to inhalation in participants engaged in cardiac interoceptive tasks. Here, we extended these findings to the time-frequency domain by reanalysing our previous dataset. We investigated heartbeat-modulated cortical oscillations, examining power, inter-trial coherence, and functional connectivity across the respiratory cycle at rest, during a cardiac interoceptive task (heartbeat counting), and an exteroceptive control task (cardiac-tone counting). Results revealed that during the heartbeat counting task, late heartbeat-related power, inter-trial coherence, and functional connectivity increased during exhalation compared to inhalation, particularly in the alpha and theta frequency bands. These effects were primarily localized to right fronto-centro-parietal electrodes. Furthermore, we identified interactive relationships between heartbeat-evoked potential and heartbeat-modulated cortical oscillations in the alpha band that predicted interoceptive accuracy. These relationships were independent of cardiac physiology and were absent in the exteroceptive task. We proposed a model of cardio-respiratory interactions within the framework of interoceptive predictive coding, suggesting that these interactions occur at multiple levels of the interoceptive hierarchy: peripheral, brainstem, and cortical. Our interpretation highlights the role of heartbeat-related alpha-band modulations in enhancing the precision-weighting of cardiac prediction errors, thereby facilitating attentional allocation to interoceptive signals and the suppression of task-irrelevant distractors, particularly during exhalation.

neuroscience↗

bioRxiv2025

Respiration facilitates behaviour during multisensory integration

The brain processes information from the external environment alongside signals generated by the body. Among bodily rhythms, respiration emerges as a key modulator of sensory processing. Multisensory integration, the non-linear combination of information from multiple senses to reduce environmental uncertainty, may be influenced by respiratory dynamics. This study investigated how respiration modulates reaction times and multisensory integration in a simple detection task. Forty healthy participants were presented with unimodal (Auditory, Visual, Tactile) and bimodal (Audio-Tactile, Audio-Visual, Visuo-Tactile) stimuli while their respiratory activity was recorded. Results revealed that reaction times systematically varied with respiration, with faster responses during peak inspiration and early expiration but slower responses during the expiration-to-inspiration transition. Applying the race model inequality approach to quantify multisensory integration, we found that Audio-Tactile and Audio-Visual stimuli exhibited the highest integration during the expiration-to-inspiration phase. These findings conceivably reflect respiration phase-locked changes in cortical excitability which in turn, orchestrates multisensory integration. Interestingly, participants also tended to adapt their respiratory cycles, aligning response onsets preferentially with early expiration. This suggests that, rather than a mere bottom-up mechanism, respiration is actively adjusted to maximise the signal-to-noise balance between interoceptive and exteroceptive signals.

neuroscience↗

bioRxiv2023

The interplay between focus of attention, respiratory phases, and the Heartbeat Evoked Potential

The Heartbeat Evoked Potential (HEP) is an EEG fluctuation that reflects the cortical processing of cardiac signals. HEP amplitude increases during various tasks involving cardiac interoception. Recent research has also indicated that HEP amplitude and cardiac interoceptive accuracy are higher during exhalation compared to inhalation. This difference may be due to the suppression of heartbeat-related sensations during inhalation and the amplification of sensations during exhalation through attentional mechanisms. Despite significant advancements in HEP research, the interactions between the HEP, interoceptive attention, and respiration are still unclear. In this study, we developed a novel experimental paradigm to investigate the relationship between HEP amplitude and respiratory phases during tasks that involve attention to cardiac interoception, non-cardiac interoception (specifically, respiration), and exteroceptive stimuli. The tasks included the Heartbeat Counting Task and the Breath Counting Task as interoceptive tasks, as well as the Cardiac-Tone Counting Task and the Breath-Tone Counting Task as exteroceptive tasks. Results demonstrated significant increases in HEP amplitude during the Heartbeat Counting Task compared to the Cardiac-Tone Counting Task and the Breath Counting Task, mostly observed over fronto-central electrodes in a late time-window. Notably, the amplitude increases during the Heartbeat Counting Task were primarily driven by HEPs recorded during exhalation, while inhalation had minimal impact. These findings align with the predictive coding model of interoceptive perception, suggesting that HEP amplitude reflects a precision-weighting process of prediction errors related to cardiac sensations that is specifically influenced by attention directed toward the heart. Furthermore, our findings emphasize the crucial role of exhalation in this precision-weighting process. These results may have considerable implications for the development of respiratory interventions to fine-tune cardiac interoception.

neuroscience↗

bioRxiv2023

Local and Global Measures of Information Storage for the Assessment of Heartbeat-Evoked Cortical Responses

ObjectiveBrain-heart interactions involve bidirectional effects produced by bottom-up input at each heartbeat, and top-down neural regulatory responses of the brain. While the cortical processing of the heartbeat is usually investigated through the analysis of the Heartbeat Evoked Potential, in this study we propose an alternative approach based on the variability in the predictability of the brain dynamics induced by the heartbeat. MethodsIn a group of eighteen subjects in whom simultaneous recording of the electroencephalogram (EEG) and electrocardiogram was performed in a resting-state, we analyzed the temporal profile of the local Information Storage (IS) to detect changes in the regularity of EEG signals in time windows associated with different phases of the cardiac cycle at rest. ResultsThe average values of the local IS were significantly higher in the parieto-occipital areas of the scalp, suggesting an activation of the Default Mode Network, regardless of the cardiac cycle phase. In contrast, the variability of the local IS showed marked differences across the cardiac cycle phases. ConclusionOur results suggest that cardiac activity influences the predictive information of EEG dynamics differently in the various phases of the cardiac cycle. SignificanceThe variability of local IS measures can represent a useful index to identify spatio-temporal dynamics within the neurocardiac system, which generally remain overlooked by the more widely employed global measures.

neuroscience↗

bioRxiv2022

Brain-heart interactions are optimized across the respiratory cycle via interoceptive attention

Respiration and heartbeat continuously interact within the living organism at many different levels, representing two of the main oscillatory rhythms of the body and providing major sources of interoceptive information to the brain. Despite the modulatory effect of respiration on exteroception and cognition has been recently established in humans, its role in shaping interoceptive perception has been scarcely investigated so far. In two independent studies, we investigated the effect of spontaneous breathing on cardiac interoception by assessing the Heartbeat Evoked Potential (HEP) in healthy humans. In Study 1, we compared HEP activity for heartbeats occurred during inhalation and exhalation in 40 volunteers at rest. We found higher HEP amplitude during exhalation, compared to inhalation, over fronto-centro-parietal areas. This suggests increased brain-heart interactions and improved cortical processing of the heartbeats during exhalation. In Study 2, we tested the respiratory phase-dependent modulation of HEP activity in 20 volunteers during Exteroceptive and Interoceptive conditions of the Heartbeat Detection (HBD) task. In these conditions, participants were requested to tap at each heartbeat, either listened to or felt, respectively. Results showed higher HEP activity and higher detection accuracy at exhalation than inhalation in the Interoceptive condition only. These effects were positively correlated, suggesting a link between optimization of both cortical processing of cardiac signals and perception of heartbeats across the respiratory cycle. Direct comparisons of Interoceptive and Exteroceptive conditions confirmed stronger respiratory phase-dependent modulation of HEP and accuracy when attention was directed towards the interoceptive stimuli. Overall, we provide data showing that respiration shapes cardiac interoception at the neurophysiological and behavioural levels. Specifically, exhalation may allow attentional shift towards the internal bodily states.

neuroscience↗

bioRxiv2021

Sleep Slow Oscillations and Spindles encode ocular dominance plasticity and promote its consolidation in adult humans

Sleep and plasticity are highly interrelated, as sleep slow oscillations and sleep spindles are associated with consolidation of Hebbian-based processes. However, in adult humans, visual cortical plasticity is mainly sustained by homeostatic mechanisms, for which the role of sleep is still largely unknown. Here we demonstrate that non-REM sleep stabilizes homeostatic plasticity of ocular dominance induced in adult humans by short-term monocular deprivation: the counter intuitive and otherwise transient boost of the deprived eye was preserved at the morning awakening (>6 hours after deprivation). Subjects exhibiting a stronger boost of the deprived eye after sleep had increased sleep spindle density in frontopolar electrodes, suggesting the involvement of distributed processes. Crucially, the individual susceptibility to visual homeostatic plasticity soon after deprivation correlated with the changes in sleep slow oscillations and spindle power in occipital sites, consistent with a modulation in early occipital visual cortex.

neuroscience↗