Biology subjects

Torterolo, P.

Publications and source records attributed to Torterolo, P..

At least 19 recordsLinked to original sources

bioRxiv2026

Maturation of Sleep EEG Complexity in Preterm Newborns: Insights from Lempel-Ziv and Joint Lempel-Ziv Analyses

The development of the sleep-wake cycle reflects the progressive structural and functional maturation of the brain. However, the organization of neural dynamics during prematurity remains incompletely understood. In this study, we analyzed the EEG from 54 polysomnographic recordings obtained from 39 preterm infants, grouped according to postmenstrual age (PMA) into three categories: 30-31, 32-33 and 34-35 weeks. Lempel-Ziv Complexity (LZC) and Joint Lempel-Ziv Complexity (JLZC) of the electroencephalogram (EEG) were analyzed during active sleep (AS), quiet sleep (QS), and indeterminate sleep (IS). LZC computed from the raw, unfiltered recordings were significantly higher during QS than during AS and increased with PMA during AS. To further refine the analysis, LZC was also evaluated separately in the low-frequency (1-15.5 Hz) and high-frequency (16-30 Hz) EEG bands. In the low-frequency band, LZC was consistently higher during QS than during AS, an effect that was most pronounced in more immature groups. Furthermore, LZC increased with maturation particularly during AS. Sleep-state comparisons of LZC in the high-frequency EEG band also revealed higher values during QS than during AS across all PMA groups. Moreover, in contrast to the low-frequency band, LZC progressively decreased with advancing PMA both in AS and QS, suggesting that the neural mechanisms underlying low- and high-frequency EEG activity follow distinct maturational trajectories. Interestingly, larger LZC in the temporal cortex and interhemispheric differences were detected in the 32-33 PMA group. On the other hand, JLZC analysis revealed greater joint spatiotemporal dynamics across EEG channels during QS than during AS, with consistently higher JLZC values in temporal regions and lower in occipital regions. Together, these findings show that these complexity metrics distinguishes sleep states and captures maturational changes in EEG activity in preterm infants. These results provide novel insights into early brain development and suggest potential quantitative biomarkers of neonatal brain maturation.

neuroscience↗

bioRxiv2026

Thalamic and cortical signals synergistically represent auditory prediction errors

Prediction errors (PEs) are commonly described as cortical signals generated within sensory hierarchies, but whether the thalamus participates in their encoding and transmission remains unclear. We recorded Local Field Potentials (LFP) from the medial and lateral geniculate nuclei and electrocorticography (ECoG) from multiple cortical regions in three awake cats during two auditory prediction tasks. Mutual information (MI) analyses revealed PE encoding in both thalamic and cortical signals. Co-information (co-I) analyses showed off-diagonal temporal synergy between early and later thalamic response components, consistent with an early response inducing a neural state change that shaped the informational content of subsequent activity. Multivariate co-information (MVCo-I) further revealed that thalamic and cortical population activity carried complementary PE information unavailable from either thalamic or cortical areas alone. These synergistic interactions were reliable across animals for violations of structured auditory sequences and weaker for repetition-based deviants. These findings show that auditory PEs are not simply relayed or duplicated across the thalamocortical hierarchy. Instead, they emerge through state-dependent transformations within the thalamus and complementary interactions between thalamic and cortical populations, identifying the thalamus as an active node of context-dependent PE processing.

neuroscience↗

bioRxiv2026

Modafinil Modulation of Oscillatory and Aperiodic Brain Activity in Rats Across Wakefulness and Subsequent Sleep

Cortical states shape sensory processing, decision-making, and behavior, and are characterized by distinct patterns of neuronal oscillatory activity. Pharmacological agents can modulate these states and their underlying electrophysiological signatures. Modafinil is a widely used wake-promoting agent and cognitive enhancer, but its effects on cortical oscillations are not fully understood. In this study, we evaluated the effect of modafinil on cortical activity during wakefulness and subsequent sleep. Ten male Wistar rats were implanted with electrocorticographic electrodes and recorded following oral administration of modafinil or its vehicle. Our results show that modafinil increased wakefulness in a dose-dependent manner, with doses of 200 and 300 mg/kg producing prolonged wake episodes and reducing hypnogram complexity. During wakefulness, modafinil enhanced gamma-band power in anterior cortices, an effect primarily driven by increases in the aperiodic rather than oscillatory components. Although no sleep rebound was observed, subsequent NREM sleep exhibited increased delta power, particularly in anterior regions, indicating heightened sleep pressure. In conclusion, our findings demonstrate that modafinil-induced wakefulness is associated with an enhanced aperiodic gamma band component at the anterior cortices in the EEG. Furthermore, modafinil modulates sleep homeostasis by enhancing NREM sleep intensity rather than extending its duration.

neuroscience↗

bioRxiv2025

Early Sleep-Dependent Sensory Gating in the Olfactory System

Disconnection from the external world is a defining feature of sleep. Although most models attribute sensory gating to thalamocortical mechanisms, the olfactory system--bypassing the thalamus--offers a unique window into earlier stages of sensory disconnection. Here, we combine chronic and acute recordings in rodents to test whether nasal sensory inputs are internalized during sleep. We show that respiration-locked potentials and gamma activity in the olfactory bulb are strongly modulated by brain state: they diminish during sleep and reappear during wakefulness and cortical activation. This gating occurs independently of respiratory dynamics and arises near the first synapse of the olfactory pathway. Finally, we find that neocortical slow-wave activity correlates with reduced connectiveness, with coupling progressively vanishing as sleep deepens. These findings reveal a sleep-dependent sensory gating mechanism at early stages of a non-thalamic pathway, providing new insights into the neural substrates of sensory disconnection during sleep.

neuroscience↗

bioRxiv2025

Differential effects of postpartum sleep restriction on maternal and offspring immunity in the rat

Backgroundsleep disturbances can trigger a wide range of physiological consequences, affecting hormonal regulation, metabolism, cognitive function, and immune responses. Human mothers worldwide frequently experience sleep restriction and fragmentation, a pattern also observed in other mammalian mothers, such as rats. These alterations may add to sleep disturbances unrelated to motherhood. Considering this, we wondered about the impact of sleep restriction in postpartum mother rats on their immunological status. Furthermore, given that early-life experiences can shape the immune system and that even subtle parental changes can influence offspring development, we hypothesized that maternal sleep loss might also exert detrimental effects on the pups. In this study, we investigated the effects of acute and chronic maternal sleep restriction during the postpartum period on immune parameters in both mother rats and their offspring by analyzing antibody titers and systemic inflammation. Methodsmother rats were surgically implanted with electrodes for polysomnographic recordings and for sleep deprivation (deep electrodes targeting the mesopontine wake-promoting area). From postpartum day 5 to day 9, lactating dams were randomly assigned to one of three groups: chronic sleep restriction (CSR; 6 h of sleep deprivation per day for five consecutive days), acute sleep restriction (ASR; 6 h of sleep deprivation only on postpartum day 9), or control (undisturbed). On postpartum day 9, mothers were milked, and blood samples from both mothers and pups were subsequently collected. ELISA assays quantified IL-17A, IL-6, IgG, and IgG2a in maternal serum; IgG and IgG2a in milk; and IgG in pup serum. Hematological parameters, including leukocyte profiles, were also assessed in peripheral blood of dams and pups. Resultsmaternal immune parameters analyzed remained unaffected by sleep restriction. IgG levels were lower in male pups from mothers subjected to ASR (5560 {+/-} 734 {micro}g/mL) compared with the control group (8666 {+/-} 463 {micro}g/mL; p = 0.025), whereas female pups showed no significant changes. Additionally, both female (4.10 {+/-} 0.58) and male (3.81 {+/-} 0.42) pups from dams subjected to CSR exhibited higher absolute lymphocytes counts relative to the control group (females: 2.28 {+/-} 0.25, p = 0.004; males: 2.44 {+/-} 0.25; p = 0.029). ConclusionsChronic and acute maternal sleep restriction had distinct impacts on offspring immunity, altering serum antibody and leukocyte profiles, while leaving maternal parameters unaffected. These results indicate that maternal sleep loss can influence the offspring even in the absence of detectable maternal immune alterations, with male pups being especially susceptible.

immunology↗

bioRxiv2025

Dual hypocretin receptor antagonism enhances sleep and nursing behavior in lactating rats.

Hypocretins (also known as orexins) are neuropeptides that regulate the sleep-wake cycle and modulate various behaviors, including maternal behavior. They act through two receptor subtypes: hypocretin receptor 1 (HcrtR1) and hypocretin receptor 2 (HcrtR2). Although Dual Orexin Receptor Antagonists (DORAs) are clinically used as hypnotics, most preclinical studies with these drugs have been conducted in males, with limited research in females, leaving the postpartum period largely unexplored. Here, we examined the impact of the DORA Suvorexant on sleep and maternal behavior in lactating rats. Lactating and virgin female rats were implanted with electrodes for polysomnographic recording. Using a counterbalanced design, Suvorexant was orally administered at doses of 0, 10 (SUV10), and 30 mg/kg (SUV30) to virgin rats in diestrus and to lactating rats between postpartum days 4 and 8. Sleep recordings and maternal behaviors were assessed during the light phase for six hours following the administration of the drug. Suvorexant reduced wakefulness and increased slow wave sleep, intermediate state, and REM sleep in both groups, with a stronger effect in virgin females. In lactating rats, Suvorexant increased nursing time and milk ejections, while reducing active maternal behavior such as pup-licking. These findings demonstrate that dual hypocretin receptor antagonism produces hypnotic effects and selectively modulates maternal behavior, promoting nursing while reducing active maternal behavior.

neuroscience↗

bioRxiv2025

Study of changes in brain dynamics during sleep cycles in dogs under effect of trazodone

Sleep is a fundamental biological process essential for cognitive function, memory consolidation, and overall health in both humans and animals. Dogs, in particular, share many physiological and neurological similarities with humans, making them a valuable model for sleep research. Similar to humans, dogs can experience sleep disorders that disrupt sleep cycles and impair cognitive function. While serotonin antagonist and reuptake inhibitors (SARIs), like trazodone, have been shown to alleviate these conditions in dogs, their underlying neural mechanisms remain poorly understood. This study investigates the effects of trazodone on brain dynamics in healthy dogs using electroencephalographic (EEG) analysis. We compared treated subjects with a control group by characterizing EEG activity across wakefulness, drowsiness, Non-REM (NREM), and REM sleep states. Hypnogram analysis was used to assess sleep architecture, including alterations in cycle patterns and time spent in each stage. Additionally, we examined linear and non-linear EEG dynamics using Power Spectral Density (PSD), Permutation Entropy (PE), and Lempel-Ziv complexity (LZC), as well as connectivity changes through Phase Lag Index (PLI) and coherence analysis. Our findings indicate that trazodone significantly alters sleep structure by modifying sleep cycles, reducing power in lower frequency bands across most sleep stages, and increasing power in frequencies above 13 Hz during Drowsiness and NREM. Furthermore, treated dogs exhibited increased signal entropy and complexity in lower frequency bands across all sleep stages, along with a reduction in brain connectivity in most stages and frequency bands. These results provide new insights into the short-term effects of trazodone on brain activity during sleep, with potential implications for its clinical use as a sleep aid in dogs.

animal behavior and cognition↗

bioRxiv2024

Higher-Order Interaction Analysis via Hypergraph Models for Studying Multidimensional Neuroscience Data.

Higher-Order Interaction (HOI) theory offers a powerful framework for capturing complex, non-linear relationships within multidimensional systems, moving beyond traditional pairwise graph methods to encompass multi-way interactions. This study applies HOI analysis, specifically using hypergraph theory, to explore intricate connectivity patterns in electrophysiological signals from neuroscience. Hypergraphs were constructed from connectivity data across various frequency bands, characterized through metrics such as spectral entropy, hyperedge centrality, and vertex centrality, and compared using spectral and centrality distance measures. Three distinct neurophysiological datasets were analyzed: intracranial EEG signals from rats during different sleep stages, scalp EEG data to distinguish between epilepsy types, and MEG recordings of seizure dynamics. The findings highlight the effectiveness of hypergraph-based HOI analysis in mapping neural dynamics across normal and pathological brain states. In sleep studies, it reveals distinct connectivity patterns between REM and NREM stages, while in epilepsy, it differentiates seizure types and stages, identifying spectral entropy as a potential marker for seizure onset. Notably, HOI analysis captures differences between primary and secondary generalized epilepsy, suggesting enhanced diagnostic accuracy. This approach provides a powerful tool for understanding complex neural interactions in high-dimensional data.

neuroscience↗

bioRxiv2024

Regulation of REM Sleep Onset and Homeostasis by Preoptic Glutamatergic Neurons

The preoptic area of the hypothalamus is key for the control of sleep onset and sleep homeostasis. Although traditionally considered exclusively somnogenic, recent studies identified a group of preoptic glutamatergic neurons that promote wakefulness. Specifically, our previous investigations demonstrated that chemogenetic stimulation of glutamatergic neurons within the medial-lateral preoptic area (MLPO_VGLUT2) promotes wakefulness, fragments non-rapid eye movement sleep (NREMs), and suppresses REM sleep (REMs). This evidence is further supported by recent work showing that preoptic glutamatergic neurons are activated during microarousals that fragment sleep in response to stress, and optogenetic stimulation of these neurons promotes microarousals and wakefulness. Thus, while the wake-promoting function of MLPO_VGLUT2 is clear, their role in sleep homeostasis has not been assessed. We tested the hypothesis that MLPO_VGLUT2 are wake-active, and their activation will increase wakefulness and disrupt sleep homeostasis via projections to arousal-promoting systems. Using fiber photometry, we found that MLPO_VGLUT2 were highly active during REMs, wakefulness and brief arousals, and remained minimally active during NREMs. Chemogenetic stimulation of MLPO_VGLUT2 inhibited REMs onset and suppressed the REMs homeostatic response after total sleep deprivation. Chemogenetic inhibition of MLPO_VGLUT2 increased REMs time (during the light phase only) but did not influence REMs and NREMs homeostasis. Anterograde projection mapping revealed that MLPO_VGLUT2 innervate central regions that promote wakefulness and inhibit REMs. We conclude that MLPO_VGLUT2 powerfully suppress REMs and that exogenous --and possibly pathologic-- activation of these neurons disrupts REMs recovery, presumably by directly or indirectly activating REMs-inhibitory mechanisms. SIGNIFICANCE STATEMENTThe preoptic area of the hypothalamus has been extensively studied and its role in sleep regulation is well-established. Importantly, recent work identified a group of preoptic glutamatergic neurons (MLPO_VGLUT2) that are wake-active and promote wakefulness. However, whether these neurons influence sleep homeostasis remains unknown. We demonstrate that MLPO_VGLUT2 are maximally active during REM sleep (REMs), wakefulness and brief arousals from sleep, and innervate wake-promoting and REMs-inhibitory regions. MLPO_VGLUT2 stimulation inhibits REMs and REMs rebound after sleep deprivation, whereas their inactivation increases REMs but does not alter REMs homeostatic response. We thus identified a preoptic mechanism that powerfully suppresses REMs, which we propose may engage during normal sleep-to-wake transitions to block REMs intrusions into subsequent wakefulness.

neuroscience↗

bioRxiv2024

Differential Effects of Haloperidol on Neural Oscillations During Wakefulness and Sleep

The electrical activity of the brain, characterized by its frequency components, reflects a complex interplay between periodic (oscillatory) and aperiodic components. These components are associated with various neurophysiological processes, such as the excitation-inhibition balance (aperiodic activity) or interregional communication (oscillatory activity). However, we do not fully understand whether these components are truly independent or if different neuromodulators modulate them in different ways. The dopaminergic system has a critical role for cognition and motivation, being a potential modulator of these power spectrum components. To improve our understanding of these questions, we investigated the differential effects of this system on these components using electrocorticogram recordings in cats, which show clear oscillations and aperiodic 1/f activity. Specifically, we focused on the effects of haloperidol (a D2 receptor antagonist) on oscillatory and aperiodic dynamics during wakefulness and sleep. By parameterizing the power spectrum into these two components, our findings reveal a state-dependent modulation of oscillatory activity by the D2 receptor across the brain. Surprisingly, aperiodic activity was not significantly affected and exhibited inconsistent changes across the brain. This suggests a nuanced interplay between neuromodulation and the distinct components of brain oscillations, providing insights into the selective regulation of oscillatory dynamics in awake states.

neuroscience↗

bioRxiv2024

Communication subspace dynamics of the canonical olfactory pathway

Understanding how different brain areas communicate is crucial for elucidating the mechanisms underlying cognition. A possible way for neural populations to interact is through a communication subspace, a specific region in the state-space enabling the transmission of behaviorally-relevant spiking patterns. In the olfactory system, it remains unclear if different populations employ such a mechanism. Our study reveals that neuronal ensembles in the main olfactory pathway (olfactory bulb to olfactory cortex) interact through a communication subspace, which is driven by nasal respiration and allows feedforward and feedback transmission to occur segregated along the sniffing cycle. Moreover, our results demonstrate that subspace communication depends causally on the activity of both areas, is hindered during anesthesia, and transmits a low-dimensional representation of odor.

neuroscience↗

bioRxiv2023

Noribogaine effects on wakefulness and sleep

Ibogaine is a potent atypical psychedelic that has gained considerable attention due to its antiaddictive and antidepressant properties in preclinical and clinical studies. Previous research from our group showed that ibogaine suppresses sleep and produces an altered wakefulness state which resembles natural REM sleep. However, after systemic administration, ibogaine is rapidly metabolized to noribogaine, which also shows antiaddictive effects and a distinct pharmacological profile, making this drug a promising therapeutic candidate. Therefore, whether the sleep/wake alterations depend on ibogaine or its principal metabolite noribogaine remains unknown. To answer this question, we conducted polysomnographic recordings in rats following the administration of pure noribogaine. Our results show that noribogaine promotes wakefulness while reducing slow-wave sleep and blocking REM sleep. Thus, like ibogaine, noribogaine significantly alters the sleep-wake architecture, highlighting the possible role of serotonin reuptake inhibition as a likely candidate underlying the wake-promoting and REM sleep-suppressing effects.

neuroscience↗

bioRxiv2023

Characterizing the power spectrum dynamics of the NREM to REM sleep transition

The transition from NREM to REM sleep is considered a transitional or intermediate stage (IS), characterized by high amplitude spindles in the frontal cortex and theta activity in the occipital cortex. Early reports in rats showed an IS lasting from 1 to 5 s, but recent studies suggested a longer duration of this stage. To further characterize the IS, we analyzed its spectral characteristics on electrocorticogram (ECoG) recordings of the olfactory bulb (OB), motor (M1), somato-sensory (S1) and secondary visual cortex (V2) in twelve Wistar male adult rats. By comparing the IS to consolidated NREM/REM epochs, our results reveal that the IS has specific power spectral patterns that statistically differ from both NREM and REM sleep states. Specifically, the main findings were that sigma (11-16 Hz) and beta (17-30 Hz) power in OB, M1, and S1 increased during the IS compared to NREM and REM sleep and began 55 s before REM sleep onset. Additionally, low gamma (31-48 Hz) in the OB started transitioning from NREM levels to REM ones 65 s before its onset. Finally, the high-frequency oscillations (102-198 Hz) in OB, M1, and S1 showed a power increase that began 40 s before REM sleep and reached REM sleep values 10 s after its onset. Thus, we argue that the NREM to REM transition contains its own spectral profile and is more extended than previously described.

neuroscience↗

bioRxiv2023

Dorsal and median raphe neuronal firing dynamics characterized by non-linear metrics

The dorsal (DRN) and median (MRN) raphe are the main serotonergic nuclei, being implicated in sleep and mood regulation. The DRN is mainly serotonergic, where neurons have regular spiking activity, slow firing rate (FR), and long action potential duration (APD). The MRN is divided in a median serotonergic region and a paramedian region, containing principally GABAergic neurons, resulting in more diverse neurochemical and electrophysiological features. In the present study, we aimed to enrich the characterization of the raphe nuclei neurons by using non-linear metrics. This was done by analyzing the neuronal basal firing profile in both nuclei of urethane-anesthetized rats using Ordinal Patterns (OP) Entropy, Bins Entropy, and Permutation Lempel-Ziv Complexity (PLZC). In a first step, we found that typical linear metrics - such as FR, coefficient of variation (CV), and APD - fail to distinguish between MRN and DRN neurons, while OP entropy is significantly different between these nuclei. We also found that the FR has a strong linear relationship with CV, Bins Entropy, and PLZC. Similarly, CV has a strong correlation with FR and Bins Entropy, whereas PLZC shows a strong linear fit with Bins Entropy. However, OP Entropy has either a weak or no linear relationship with the rest of the metrics tested, suggesting that OP Entropy is a good metric to differentiate neuronal firing profiles. In a second step, we studied how these metrics are affected by the oscillatory properties of the firing patterns. We found that all metrics are sensitive to rhythmicity - with the exception of OP Entropy. Again, this highlights OP Entropy as a powerful and useful quantity for the characterization of neuronal discharge patterns.

neuroscience↗

bioRxiv2022

Electrophysiological characterization of medial preoptic neurons in lactating rats and its modulation by hypocretin-1

The medial preoptic area (mPOA) undergoes through neuroanatomical changes across the postpartum period, during which its neurons play a critical role in the regulation of maternal behavior. In addition, this area is also crucial for sleep-wake regulation. We have previously shown that hypocretins (HCRT) within the mPOA facilitate active maternal behaviors in postpartum rats, while the blockade of endogenous HCRT in this area promotes nursing and sleep. To explore the mechanisms behind these HCRT actions, we aimed to evaluate the effects of juxta-cellular HCRT-1 administration on mPOA neurons in urethane-anesthetized postpartum and virgin female rats. We recorded mPOA single units and the electroencephalogram (EEG) and applied HCRT-1 juxta-cellular by pressure pulses. Our main results show that the electrophysiological characteristics of the mPOA neurons and their relationship with the EEG of postpartum rats did not differ from virgin rats. Additionally, neurons that respond to HCRT-1 had a slower firing rate than those that did not. In addition, administration of HCRT increased the activity in one group of neurons while decreasing it in another, both in postpartum and virgin rats. The mechanisms by which HCRT modulate functions controlled by the mPOA involve different cell populations.

neuroscience↗

bioRxiv2022

Mechanisms and functions of respiration-driven gamma oscillations in the piriform cortex

Gamma oscillations are believed to underlie cognitive processes by shaping the formation of transient neuronal partnerships on a millisecond scale. These oscillations are coupled to the phase of breathing cycles in several brain areas, possibly reflecting local computations driven by sensory inputs sampled at each breath. Here, we investigated the mechanisms and functions of gamma oscillations in the piriform (olfactory) cortex of awake mice to understand their dependence on breathing and how they relate to local spiking activity. Mechanistically, we find that respiration drives gamma oscillations in the piriform cortex, which correlate with local feedback inhibition and result from recurrent connections between local excitatory and inhibitory neuronal populations. Moreover, respiration-driven gamma oscillations are triggered by the activation of mitral/tufted cells in the olfactory bulb and are abolished during ketamine/xylazine anesthesia. Functionally, we demonstrate that they locally segregate neuronal assemblies through a winner-take-all computation leading to sparse odor coding during each breathing cycle. Our results shed new light on the mechanisms of gamma oscillations, bridging computation, cognition and physiology.

neuroscience↗

bioRxiv2022

Electroencephalographic Signatures of Canine Cognitive Dysfunction

Canine cognitive dysfunction (CCD) is a highly prevalent neurodegenerative disease considered the canine analog of Alzheimers disease (AD). Unfortunately, CCD cannot be cured. However, early therapeutic interventions can slow the progression of cognitive decline and improve quality of life of the patients; therefore, early diagnosis is ideal. In humans, electroencephalogram (EEG) findings specific to AD have been described, and some of them have successfully detect early stages of the disease. In this study we characterized the EEG correlates of CCD, and we compared them with the EEGs of healthy aging dogs and dogs at risk of developing CCD. EEG recordings were performed in 25 senior dogs during wakefulness. Dogs were categorized in normal, at risk of CCD or with CCD according to their score in the Rofina questionnaire. We demonstrated that, quantitative EEG can detect differences between normal dogs and dogs with CCD. Dogs with CCD experience a reduction in beta and gamma interhemispheric coherence, and higher Joint Lempel Ziv complexity. Dogs at risk of developing CCD, had higher alpha power and interhemispheric coherence, making these features potential markers of early stages of the disease. These results demonstrate that EEG could be an additional biomarker that can contribute to the diagnosis of CCD, and reinforce the CCD as a translational model of AD.

animal behavior and cognition↗

bioRxiv2021

Low Frequency Oscillations drive EEG's complexity changes during wakefulness and sleep

Recently, the sleep-wake states have been analysed using novel complexity measures, complementing the classical analysis of EEGs by frequency bands. This new approach consistently shows a decrease in EEGs complexity during slow-wave sleep, yet it is unclear how cortical oscillations shape these complexity variations. In this work, we analyse how the frequency content of brain signals affects the complexity estimates in freely moving rats. We find that the low-frequency spectrum - including the Delta, Theta, and Sigma frequency bands - drives the complexity changes during the sleep-wake states. This happens because low-frequency oscillations emerge from neuronal population patterns, as we show by recovering the complexity variations during the sleep-wake cycle from micro, meso, and macroscopic recordings. Moreover, we find that the lower frequencies reveal synchronisation patterns across the neocortex, such as a sensory-motor decoupling that happens during REM sleep. Overall, our works shows that EEGs low frequencies are critical in shaping the sleep-wake states complexity across cortical scales.

neuroscience↗