Sleep, plasticity and Conscious Experience

What We Do

Traditionally, sleep and wakefulness have been considered as two global, mutually exclusive states. However, this view has been challenged by the discovery that sleep and wakefulness are locally regulated and that islands of these two states may often coexist in the same individual. Importantly, the local regulation of sleep seems to be key for many of the known functions of this physiological state, including the maintenance of brain functional efficiency, the consolidation or stabilization of new memories and the modulation of mood and emotional reactivity. Local changes in brain activity during sleep may also explain the emergence of particular conscious experiences in the form of dreams, and may modulate the level of sensory disconnection that is essential for a restorative sleep. On the other hand, during wakefulness, the reiterated activation of specific brain areas may lead to a state of functional fatigue, characterized by the appearance of local, sleep-like episodes. These events seem to have important consequences for behavior and cognition and may contribute to explain the known effects of sleep loss. Given these premises, alterations in the local regulation of sleep and wakefulness may represent the pathophysiological basis for symptoms observed in many sleep disorders, but also in some psychiatric or neurological disorders.


ONGOING PROJECTS

  • The behavioral and neural correlates of local sleep-like episodes during wakefulness (collaboration with University of Wisconsin)

  • The cortical and subcortical correlates of sleep slow waves and arousals (collaboration with UniMoRe)

  • The relationship between slow waves and conscious experiences in sleep (collaboration with University of Lausanne)

  • The anatomo-functional bases of sensory disconnection during sleep

Who We Are

Principal InvestigatorAssistant ProfessorScholar, ResearchGate, Twitter
VALENTINA ELCE
PhD Student
DEMETRIO GROLLERO
PhD Student
DAMIANA BERGAMO
PhD Student
LEILA SALVESEN
PhD Student
ELENA CAPRIGLIA
Ms.C. Student
DAVIDE BERTELLONI
Ms.C. Student

Past Members: Laura Sophie Imperatori

What We Publish

Emotion suppression failures are associated with local increases in sleep-like activity

Giulia Avvenuti, Davide Bertelloni, Giada Lettieri, Emiliano Ricciardi, Luca Cecchetti, Pietro Pietrini, Giulio BernardibioRxiv, 2020. DOI: 10.1101/2020.08.04.235978
Emotion self-regulation relies both on cognitive and behavioral strategies implemented to modulate the subjective experience and/or the behavioral expression of a given emotion. While it is known that a network encompassing fronto-cingulate and parietal brain areas is engaged during successful emotion regulation, the functional mechanisms underlying failures in emotion suppression are still unclear. In order to investigate this issue, we analyzed video and high-density EEG recordings of nineteen healthy adult subjects during an emotion suppression (ES) and a free expression (FE) task performed on two consecutive days. Changes in facial expression during ES, but not FE, were preceded by local increases in sleep-like activity (1-4Hz) in in brain areas responsible for emotional suppression, including bilateral anterior insula and anterior cingulate cortex, and in right middle/inferior frontal gyrus (p<0.05, corrected). Moreover, shorter sleep duration the night prior to the ES experiment correlated with the number of behavioral errors (p=0.01) and tended to be associated with higher frontal sleep-like activity during emotion suppression failures (p=0.05). These results indicate that local sleep-like activity may represent the cause of emotion suppression failures in humans, and may offer a functional explanation for previous observations linking lack of sleep, changes in frontal activity and emotional dysregulation.

Cortical and subcortical hemodynamic changes during human sleep slow waves

Betta, Handjaras, Leo, Federici, Farinelli, Ricciardi, Siclari, Meletti, Ballotta, Benuzzi, Giulio BernardibioRxiv, 2020. DOI: 10.1101/2020.04.29.067702
EEG slow waves, the hallmarks of NREM sleep, are closely linked to the restorative function of sleep and their regional cortical distribution reflects plasticity- and learning-related processes. Here we took advantage of simultaneous EEG-fMRI recordings to map cortical and subcortical hemodynamic (BOLD) fluctuations time-locked to sleep slow waves. Recordings were performed in twenty healthy adults during an afternoon nap. Slow waves were associated with BOLD-signal increases in the brainstem and in portions of thalamus and cerebellum characterized by preferential functional connectivity with limbic and somatomotor areas, respectively. At the cortical level, significant BOLD-signal decreases were found in several areas, including insula and somatomotor cortex, and were preceded by slow signal increases that peaked around slow-wave onset. EEG slow waves and BOLD fluctuations showed similar cortical propagation patterns, from centro-frontal to temporo-occipital cortices. These regional patterns of hemodynamic-electrical coupling are consistent with theoretical accounts of the functions of sleep slow waves.

Integrity of corpus callosum is essential for the cross-hemispheric propagation of sleep slow waves: a high-density EEG study in split-brain patients

Avvenuti, Handjaras, Betta, Cataldi, Imperatori, Lattanzi, Riedner, Pietrini, Ricciardi, Tononi, Siclari, Polonara, Fabri, Silvestrini, Bellesi, BernardiJournal of Neuroscience, 2020. DOI: 10.1523/JNEUROSCI.2571-19.2020
The slow waves of NREM-sleep behave as traveling waves and their propagation has been suggested to reflect the integrity of white matter cortico-cortical connections. To directly assess this hypothesis, here we investigated the role of the corpus callosum in the cortical spreading of NREM slow waves through the study of a rare population of totally callosotomized patients. Our results demonstrate a causal role of the corpus callosum in the cross-hemispheric traveling of sleep slow waves. Additionally, we found that callosotomy does not affect the relative tendency of each hemisphere at generating slow waves. Incidentally, we also found that slow waves tend to originate more often in the right than in the left hemisphere in both callosotomized and healthy adult individuals.

Regional Delta Waves In Human Rapid Eye Movement Sleep

Bernardi, Betta, Ricciardi, Pietrini, Tononi, SiclariJournal of Neuroscience, 2019. DOI: 10.1523/JNEUROSCI.2298-18.2019
The EEG slow wave is typically considered a hallmark of nonrapid eye movement (NREM) sleep, but recent work in mice has shown that it can also occur in REM sleep. By analyzing high-density EEG recordings collected in healthy adult individuals, we show that REM sleep is characterized by prominent delta waves also in humans. In particular, we identified two distinctive clusters of delta waves with different properties: a frontal-central cluster characterized by faster, activating “sawtooth waves” that share many characteristics with ponto-geniculo-occipital waves described in animals and a medial-occipital cluster containing slow waves that are more similar to NREM sleep slow waves. These findings indicate that REM sleep is a spatially and temporally heterogeneous state and may contribute to explaining its known functional and phenomenological properties.

Our Collaborations

What We Develop

Our Talks

Avvenuti - The corpus callosum is essential for the cross-hemispheric propagation of sleep slow waves: a high-density EEG study in totally callosotomized patients. Congress of the Word Sleep Society, Vancouver, Canada, 2019.

Imperatori - Cross-participant prediction of vigilance stages through the combined use of wpli and wsmi eeg functional connectivity metrics. Congress of the Word Sleep Society, Vancouver, Canada, 2019.

Avvenuti - Il ruolo del corpo calloso nella propagazione crossemisferica delle onde lente del sonno: uno studio in pazienti con callosotomia totale. Congress of the Italian Society of Sleep Medicine (AIMS), Genova, Italy, 2019.

Betta - Slow waves of sleep are associated with increased thalamic activity and with a delayed decreased activity in primary sensory cortices. Congress of the Italian Society of Sleep Medicine (AIMS), Genova, Italy, 2019.

Bernardi - Experience-dependent regulation of sleep-need: effects on brain functioning and behavioral performance. Congress of the International Organization of Psychophysiology, Lucca, Italy, 2018.

Bernardi - The effects of acute, short-term visual deprivation on low-frequency EEG activity during wakefulness and sleep. Congress of the Word Sleep Society, Prague, Czech Republic, 2017.