Biology subjects

Buonviso, N.

Publications and source records attributed to Buonviso, N..

7 recordsLinked to original sources

bioRxiv2026

No Evidence for a Wakeful Rest Benefit on Associative Memory: A Within-Participant EEG Study

Wakeful rest after learning has been proposed to facilitate memory consolidation compared to engaging in a distraction task, with prior EEG studies linking slow oscillation power during rest to better memory performance. However, replication attempts have yielded mixed results. We investigated whether 10 minutes of wakeful rest would enhance associative memory performance relative to 10 minutes of a hippocampus-dependent auditory short-term memory distraction task, using a within-participant design with continuous EEG recording. We employed both a replication-inspired analytical approach, closely modeled on prior work, and a data-specific approach adapted to our dataset. Contrary to our hypotheses, we found no advantage of rest over distraction on associative memory performance. We did, however, observe an order effect: performance was better for the second learning than the first, and this improvement was more pronounced when rest was performed second compared to first. At the neurophysiological level, neither slow oscillation nor alpha power during the post-learning period correlated with memory performance, regardless of analytical pipeline, although cross-over analyses revealed that the choice of EEG reference influenced the direction of some correlations. At the phenomenological level, self-reported mental activity during rest and distraction, as well as trait daydreaming frequency, were not related to memory outcomes, despite the two conditions inducing distinct subjective cognitive states. Together, these findings do not support a robust benefit of post-learning wakeful rest over a hippocampus-dependent distraction task for associative memory, nor do they replicate prior EEG correlates of consolidation. We discuss methodological factors, including task-learning effects in within-participant designs, the coarseness of averaged spectral power measures, and variability in EEG preprocessing pipelines, that may contribute to inconsistencies across the literature, and we call for greater standardization and transparency in future studies.

neuroscience↗

bioRxiv2024

Pleasant smells: a privileged gateway to soothing autonomic responses and improving brain-body rhythm coupling

Aromatherapy commonly uses odors to improve well-being through their evocation of positive emotions. Although knowledge in this area is often very empirical, the olfactory stimulus has different properties which, taken together, could explain why it can relax. First, olfactory sense have a direct access to the limbic system, without thalamic relay processing, which confers it a strong emotional valence. Second, when appreciated, odors can slow down breathing and cardiac rates. Third, when slow and deep, breathing can entrain brain activity, due to the mechano-sensitivity of olfactory receptors to airflows. We hypothesized that, thanks to these properties, pleasant odors could enhance the subjective feeling of relaxation, slow down body rhythms, and facilitate entrainment of brain activity by respiration. Comparing the effects of a personally pleasant odor to a personally pleasant music on psychological, physiological and neuronal responses, we showed a tendency for both odors and music to enhance subjective relaxation. However, only pleasant odors were able to 1) decrease heart rate while increasing its variability, and 2) decrease respiratory rate while enhancing the respiratory drive of brain activities, regardless of the music tempo. Overall, we demonstrated that the positive emotion evoked by a personally pleasant smell is sufficient to evoke an olfactomotor response, which, by slowing breathing, synchronizes respiration, fluctuations of heart rate and brain activity.

neuroscience↗

bioRxiv2023

State-dependent alteration of respiration in a rat model of Parkinson disease

Parkinson disease (PD) is the second most frequent neurodegenerative disorder. Besides major deficits in motor coordination, patients may also display sensory and cognitive impairments, which are often overlooked despite being inherently part of the PD symptomatology. Amongst those symptoms, respiration, a key mechanism involved in the regulation of multiple physiological and neuronal processes, appears to be altered. Importantly, breathing patterns are highly correlated with the animals behavioral states, and although respiration has been investigated in different models of PD, no study has yet taken into consideration the potential impact of behavioral state on respiration deficits in these models. To explore this variable, we first characterized the respiratory parameters in a neurotoxin-induced rat model of PD (6-OHDA) across different vigilance states: sleep, quiet waking and exploration. We noted a significantly higher respiratory frequency in 6-OHDA rats during quiet waking compared to Sham rats. A higher respiratory amplitude was also observed in 6-OHDA rats during both quiet waking and exploration. No effect of the treatment was noted during sleep. Given the relation between respiration and olfaction and the presence of olfactory deficits in PD patients, we then investigated the odor-evoked sniffing response in PD rats, using an odor habituation/cross-habituation paradigm. No substantial differences were observed in olfactory abilities between the two groups, as assessed through sniffing frequency. These results corroborate the hypothesis that respiratory impairments in 6-OHDA rats are vigilance-dependent. Our results also shed light on the importance of considering the behavioral state as an impacting factor when analyzing respiration. HighlightsO_LISpecific respiratory patterns associated to different vigilance states C_LIO_LISpecific alteration of respiration during quiet waking in a rodent model of PD C_LIO_LIPreserved olfactory abilities as assessed through sniffing in a rodent model of PD C_LI

neuroscience↗

bioRxiv2023

The timing of sleep spindles is modulated by the respiratory cycle in humans

Coupling of sleep spindles with cortical slow waves and hippocampus sharp-waves ripples is crucial for sleep-related memory consolidation. Recent literature evidenced that nasal respiration modulates neural activity in large-scale brain networks. In the rodent, this respiratory drive strongly varies according to vigilance states. Particularly, during sleep, respiration promotes the coupling between hippocampal sharp-wave ripples and cortical DOWN/UP state transitions. However, no study has examined whether sleep spindles could be respiration-modulated in humans. In this work, we aimed to investigate the influence of breathing on brain oscillations during non-rapid-eye-movement stage 2 sleep (N2) in humans by examining the coupling between sleep spindles and respiration cycle. Full night polysomnography of twenty healthy participants were analysed. Spindles and slow waves were detected during N2 sleep stage. Spindle-related sigma power as well as spindle and slow waves events were analysed according to the respiratory phase. We found a significant coupling between slow and fast spindles with respiration cycle, with enhanced sigma activity and probability of occurrence of spindles during the middle part of the expiration phase. A different coupling was observed between breathing and slow waves that were more distributed around both respiration phase transitions. Our findings suggest that breathing cycle influences the dynamics of brain activity during non-rapid-eye-movement sleep. This may enable sleep spindles to synchronize with other brain rhythms including hippocampus sharp wave ripples and facilitate information transfer between distributed brain networks.

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bioRxiv2022

Sniffing response to an odor through development in rats: modulatory role of repetition and association with an aversive event

Sniffing has proven to be a useful behavioral readout for assessing olfactory performance in adult rats. However, little is known about how sniffing response changes through ontogeny. This study thus aimed at characterizing respiratory response to an odor through development in rats using paradigms applicable to both young pups and adults. We first analyzed the sniffing response to the arrival of a novel neutral odor. Then the value of the odor was changed through either its repeated presentation (odor habituation), or its association with a foot-shock resulting in odor fear. In the habituation task, we found that at the three ages, the first presentation of the novel odor induced a clear sniffing response but the peak respiratory frequency was higher in adults than in juveniles and infants. When the odor was presented repeatedly, the sniffing response gradually faded. This habituation of the response took more trials as the animals age increases. In the fear conditioning task, the odor induced an increase in respiratory rate that persisted until the end of the session in adults and infants, while it faded rapidly in juveniles. When the odor was explicitly unpaired with the foot-shock, at the three ages the respiratory response to the odor lasted less over the session than in the paired condition. Finally, we observed that shock delivery induced a similar respiratory response at the three ages in paired and unpaired condition. Collectively these data show that sniffing response constitutes a faithful index to assess rats olfactory abilities through ontogeny.

neuroscience↗

bioRxiv2020

The deep and slow breathing characterizing rest favors brain respiratory-drive

A respiration-locked activity in the olfactory brain, mainly originating in the mechano-sensitivity of olfactory sensory neurons to air pressure, propagates from the olfactory bulb to the rest of the brain. Interestingly, changes in nasal airflow rate result in reorganization of olfactory bulb response. Therefore, if the respiratory drive of the brain originates in nasal airflow movements, then it should vary with respiration dynamics that occur spontaneously during natural conditions. We took advantage of the spontaneous variations of respiration dynamics during the different waking and sleep states to explore respiratory drive in various brain regions. We analyzed their local field potential activity relative to respiratory signal. We showed that respiration regime was state-specific, and that quiet waking was the only vigilance state during which all the recorded structures can be respiration-driven whatever the respiration frequency. We used a CO2-enriched air to change the respiratory regime associated to each state and, using a respiratory cycle-by-cycle analysis, we evidenced that the large and strong brain entrainment during quiet waking was the consequence of its associated respiration regime consisting in an optimal trade-off between deepness and duration of inspiration. These results show for the first time that changes in respiration regime alter the cortical dynamics and that the respiratory regime associated with rest is optimal for respiration to drive the brain.

neuroscience↗

bioRxiv2018

New insights from 22-kHz ultrasonic vocalizations to characterize fear responses: relationship with respiration and brain oscillatory dynamics

Fear behavior depends on interactions between the medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA), and the expression of fear involves synchronized activity in theta and gamma oscillatory activities. In addition, freezing, the most classical measure of fear response in rodents, temporally coincides with the development of sustained 4-Hz oscillations in prefrontal- amygdala circuits. Interestingly, these oscillations were recently shown to depend on the animals respiratory rhythm, supporting the growing body of evidence pinpointing the influence of nasal breathing on brain rhythms. During fearful states, rats also emit 22-kHz ultrasonic vocalizations (USV) which drastically affect respiratory rhythm. However, the relationship between 22-kHz USV, respiration and brain oscillatory activities is still unknown. Yet such information is crucial for a comprehensive understanding of how the different components of fear response collectively modulate rats brain neural dynamics. Here we trained male rats in an odor fear conditioning task, while recording simultaneously local field potentials in BLA, mPFC and olfactory piriform cortex, together with USV calls and respiration. We show that USV calls coincide with an increase in delta and gamma power and a decrease in theta power. In addition, during USV emission in contrast to silent freezing, there is no coupling between respiratory rate and delta frequency, and the modulation of fast oscillations amplitude relative to the phase of respiration is modified. We propose that sequences of USV calls could result in a differential gating of information within the network of structures sustaining fear behavior, thus potentially modulating fear expression/memory.\n\nSignificance StatementWhile freezing is the most frequently used measure of fear, it is only one amongst the different components of rodents response to threatening events. USV is another index that gives additional insight into the socioemotional status of an individual. Our study is the first to describe the effects of USV production on rats brain oscillatory activities in the fear neural network, and to relate some of them to changes in nasal breathing. A better knowledge of the impact of USV calls on brain neural dynamics is not only important for understanding the respective weight of the different components of fear response, but is also particularly relevant for rodent models of human neuropsychiatric disorders, for which socio-affective communication is severely impaired.

neuroscience↗