Slow Wave Research Articles

Imaging the large-scale and cellular response to focal traumatic brain injury in mouse neocortex.

Traumatic brain injury (TBI) affects neural function at the local injury site and also at distant, connected brain areas. However, the real-time neural dynamics in response to injury and subsequent effects on sensory processing and behavior are not fully resolved, especially across a range of spatial scales. We used in vivo calcium imaging in awake, head-restrained male and female mice to measure large-scale and cellular resolution neuronal activation, respectively, in response to a mild TBI induced by focal controlled cortical impact (CCI) injury of the motor cortex (M1). Widefield imaging revealed an immediate CCI-induced activation at the injury site, followed by a massive slow wave of calcium signal activation that traveled across the majority of the dorsal cortex within approximately 30 s. Correspondingly, two-photon calcium imaging in primary somatosensory cortex (S1) found strong activation of neuropil and neuronal populations during the CCI-induced traveling wave. A depression of calcium signals followed the wave, during which we observed atypical activity of a sparse population of S1 neurons. Longitudinal imaging in the hours and days after CCI revealed increases in the area of whisker-evoked sensory maps at early time points, in parallel to decreases in cortical functional connectivity and behavioral measures. Neural and behavioral changes mostly recovered over hours to days in our mild-TBI model, with a more lasting decrease in the number of active S1 neurons. Our results provide novel spatial and temporal views of neural adaptations that occur at cortical sites remote to a focal brain injury.

Effect of area divergence and frequency on damping of slow magnetoacoustic waves propagating along umbral fan loops

Abstract Waves play an important role in the heating of solar atmosphere, however, observations of wave propagation and damping from the solar photosphere to corona through chromosphere and transition region are very rare. Recent observations have shown propagation of 3-min slow magnetoacoustic waves (SMAWs) along fan loops from the solar photosphere to corona. In this work, we investigate the role of area divergence and frequencies on the damping of SMAWs propagating from the photosphere to the corona along several fan loops rooted in the sunspot umbra. We study the Fourier power spectra of oscillations along fan loops at each atmospheric height which showed significant enhancements in 1–2 min, 2.3–3.6 min and 4.2–6 min period bands. Amplitude of intensity oscillations in different period bands and heights are extracted after normalizing the filtered light curves with low-frequency background. We find damping of SMAW energy flux propagating along the fan loop 6 with damping lengths ≈170 km and ≈208 km for 1.5-min and 3-min period bands. We also show the decay of total wave energy content with height after incorporating area divergence effect, and present actual damping of SMAWs from photosphere to corona. Actual damping lengths in this case increases to ≈172 km and ≈303 km for 1.5-min and 3-min period bands. All the fan loops show such increase in actual damping lengths, and thus highlight the importance of area divergence effect. Results also show some frequency-dependent damping of SMAW energy fluxes with height where high-frequency waves are damped faster than low-frequency waves.

The Interactions between Smoking and Sleep

Smoking a cigarette before bed or first thing in the morning is a common habit. In this review, the relationship between smoking and sleep is investigated based on the existing literature. Out of 6504 unique items that were identified via a PubMed search related to smoking and sleep, 151 were included in this review. Tobacco smoking disrupts sleep architecture by reducing slow wave and rapid eye movement (REM) sleep and undermining sleep quality. Furthermore, smoking affects sleep-related co-morbidities, such as obstructive sleep apnea–hypopnea syndrome (OSAHS), insomnia, parasomnias, arousals, bruxism, and restless legs, as well as non-sleep-related conditions such as cardiovascular, metabolic, respiratory, neurologic, psychiatric, inflammatory, gynecologic and pediatric issues, while poor sleep quality also seems to worsen the chances of successful smoking cessation. In conclusion, the existing literature suggests that there is a wicked relation between smoking and sleep.

Habituation of Central and Electrodermal Responses to an Auditory Two-Stimulus Oddball Paradigm

The orienting reaction (OR) towards a new stimulus is subject to habituation, i.e., progressively attenuates with stimulus repetition. The skin conductance responses (SCRs) are known to represent a reliable measure of OR at the peripheral level. Yet, it is still a matter of debate which of the P3 subcomponents is the most likely to represent the central counterpart of the OR. The aim of the present work was to study habituation, recovery, and dishabituation phenomena intrinsic to a two-stimulus auditory oddball paradigm, one of the most-used paradigms both in research and clinic, by simultaneously recording SCRs and P3 in twenty healthy volunteers. Our findings show that the target stimulus was capable of triggering a more marked OR, as indexed by both SCRs and P3, compared to the standard stimulus, that could be due to its affective saliency and relevance for task completion; the application of temporal principal components analysis (PCA) to the P3 complex allowed us to identify several subcomponents including both early and late P3a (eP3a; lP3a), P3b, novelty P3 (nP3), and both a positive and a negative Slow Wave (+SW; −SW). Particularly, lP3a and P3b subcomponents showed a similar behavior to that observed for SCRs , suggesting them as central counterparts of OR. Finally, the P3 evoked by the first standard stimulus after the target showed a significant dishabituation phenomenon which could represent a sign of the local stimulus change. However, it did not reach a sufficient level to trigger an SCR/OR since it did not represent a salient event in the context of the task.

Effects of repeated cryostimulation exposures on sleep and wellness in healthy young adults

The aim of this study was to evaluate the effects of daily whole-body cryostimulation (WBC) sessions during 5 consecutive days on wellness and sleep parameters in healthy young men and women. Twenty healthy subjects (9 women; 11 men) aged 23.1 ± 2.6 years old participated in this randomized protocol, with 5 consecutive days with (CRYO) or without WBC (CONT) exposure. Sleep was analyzed over the 5 nights in each condition. Sleep quality and quantity were assessed via actimetry, cerebral activity and questionnaires. Nocturnal heart rate variability (HRV) was also recorded and questionnaires were given to assess wellness and mood. Repeated WBC exposures had a beneficial impact on mood and anxiety. It also improved subjective sleep quality (scored from 3.6 ± 0.5 pre to 3.9 ± 0.3), especially in women. Also, repeated WBC sessions modulated sleep architecture by increasing slow wave sleep duration (+7.3 ± 16.8 min) during the nights without impacting other sleep parameters, nor nocturnal HRV. In conclusion, repeated WBC seems to be an effective strategy to improve slow wave sleep duration in healthy young subjects. The reported psychological improvements may better benefit women than men.

Electroclinical characteristics and therapies of tonic spasms

BackgroudEpileptic spasms followed by a tonic component have been frequently observed in patients with late-onset spasms (LOS). However, there is a lack of comprehensive analysis and summary of clinical data related to tonic spasms (TS), including seizures, video-electroencephalogram (V-EEG), synchronous electromyography (EMG) and follow-up data.MethodsTo investigate the characteristics of TS, we prospectively collected the clinical data, including 24-h V-EEG and synchronous EMG data of 32 enrolled patients who suffered from epileptic spasms followed by a TS onset at least once during the 24-h V-EEG in the epilepsy center of Xijing Hospital between June 2015 and July 2020. The patients were prescribed anti-seizure medications (ASMs) and followed up for 2–7 years.ResultsThe average age of epilepsy onset was 48.06 ± 16.07 months (range: 25 to 88 months). Among the enrolled patients, 22 patients presented with mild intellectual deficits. During the 24-h video-EEG monitoring, an average of 6.94 TS events (range: 3 to 21) were recorded, and these TS seizures often occurred in clusters. In addition to TS, 26 patients experienced generalized tonic-clonic seizures (GTCS), atypical absence seizures, myoclonic seizure, and epileptic spasms. None of the 32 patients with TS displayed hypsarrhythmia during the 24-h video-EEG recording. A total of 28 patients showed normal EEG backgrounds. Interictal epileptic discharges, including slow waves (SW), spike/sharp slow waves (SSW), and spikes, often displayed multifocally. Notably, two patients achieved seizure freedom for more than 2 years through monotherapy with oxcarbazepine (OXC), which was associated with normalization of the EEG.ConclusionsIt is difficult to classify the patients with TS as any existing epileptic syndromes, which were distinct from West syndrome or Lennox-Gastaut syndrome. TS might be an underreported seizure type and further studies are needed to gain a more comprehensive understanding of the electro-clinical features and appropriate choice of ASMs for treating tonic spasms.

Investigation of Weld Seams of FFP2 Medical Mask by Air-Coupled Ultrasound

This work addresses the critical concern of ensuring the quality of FFP2 medical masks weld seam, focusing on air-coupled ultrasonic testing (ACUT) as a non-contact inspection method. Through C-scan procedures and through-transmission techniques at varying frequencies, the research explores the acoustic properties of medical mask materials and welding seams. Attenuation and signal phase shift measurements reveal insights into ultrasound wave interactions with different components, aligning with slow longitudinal waves. Comparative analyses of welding seam inspection setups identify the normal through-transmission setup as practical. The innovative 2nd derivative technique of received signal amplitudes, proves effective in defect detection, presenting potential advancements in non-destructive testing for medical masks, ensuring swift and contamination-free inspection while preserving mask integrity.

Wet‐Printed Stretchable and Strain‐Insensitive Conducting Polymer Electrodes: Facilitating In Vivo Gastric Slow Wave Mapping

AbstractWearable and implantable devices play a crucial role in clinical diagnosis, disease treatment, and fundamental research on the body's electrophysiology and biochemical processes. Conducting polymers are emerging as promising solutions to surpass the limitations of traditional metal‐based electrodes, offering enhanced conformability, and stretchability. However, current microfabrication techniques of CP electrodes have a number of limitations. In this study, a novel wet‐printing technique is developed for the fabrication of highly stretchable poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) microelectrodes. The wet‐printing, conducted in a liquid coagulation bath, has the advantages of being non‐contact, easy and fast to perform, and capable of printing low‐viscosity inks. Wet‐printing of PEDOT:PSS lines with a width of ≈20 µm is demonstrated. By adding D‐sorbitol as a plasticizer, an ultra‐high stretchability of PEDOT:PSS electrodes, of more than 720% is achieved while the electrodes remained conductive and strain‐insensitive up to high strains. The use of PEDOT:PSS wet‐printed electrode arrays for the electrophysiological recording from the stomach is demonstrated. The stretchable electrodes conformed swell to the tissue and recorded comparable electrophysiological signals to Au‐plated electrodes in porcine and rodent animal models. The wet‐printing approach to fabricating flexible and stretchable electrode arrays using low‐viscosity, conducting inks holds promise for applications in conformable electronics.

Clinical characteristics and prognosis of paediatric respiratory syncytial virus-related encephalopathy

BackgroundTo understand the clinical characteristics and prognosis of respiratory syncytial virus (RSV)-related encephalopathy in children.MethodsA retrospective analysis of the data of children who were diagnosed with RSV-related encephalopathy and admitted to the paediatric intensive care unit (PICU) of Beijing Children’s Hospital between November 2016 and November 2023 was performed.ResultsFour hundred and sixty-four children with RSV infection were treated in the PICU, and eight of these patients (1.7%) were diagnosed with RSV-related encephalopathy. The mean age of the patients was 24.89 (5.92 ∼ 36.86) months. Two patients had underlying diseases. The time from the onset of illness to impaired consciousness was 3 (1.88–3.75) days. Five patients had convulsions, and three patients had an epileptic status. The serum procalcitonin (PCT) level was 1.63 (0.24, 39.85) ng/ml for the eight patients, and the cerebrospinal fluid (CSF) protein level was 232 (163 ∼ 848) g/L. Among the 8 patients, four patients underwent electroencephalogram (EEG) monitoring or examination. One patient showed continuous low-voltage, nonresponsive activity, and another patient displayed persistent slow waves, the remaining two patients had negative results. One patient had a combination of acute necrotizing encephalopathy (ANE) and acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). Additionally, one patient had ANE, and another had acute brain swelling (ABS). One patient died in the hospital, and the other seven patients were discharged with improvement. Routine follow-up was conducted for 4.58(0.5 ∼ 6.50) years, and all patients fully recovered.ConclusionsRSV-related encephalopathy could have varying clinical manifestations, and some types, such as ANE and ABS, are dangerous and can lead to death.

Network signatures define consciousness state during focal seizures.

Epilepsy is a common neurological disorder affecting 1% of the global population. Loss of consciousness in focal impaired awareness seizures (FIASs) and focal-to-bilateral tonic-clonic seizures (FBTCSs) can be devastating, but the mechanisms are not well understood. Although ictal activity and interictal connectivity changes have been noted, the network states of focal aware seizures (FASs), FIASs, and FBTCSs have not been thoroughly evaluated with network measures ictally. We obtained electrographic data from 74 patients with stereoelectroencephalography (SEEG). Sliding window band power, functional connectivity, and segregation were computed on preictal, ictal, and postictal data. Five-minute epochs of wake, rapid eye movement sleep, and deep sleep were also extracted. Connectivity of subcortical arousal structures was analyzed in a cohort of patients with both SEEG and functional magnetic resonance imaging (fMRI). Given that custom neuromodulation of seizures is predicated on detection of seizure type, a convolutional neural network was used to classify seizure types. We found that in the frontoparietal association cortex, an area associated with consciousness, both consciousness-impairing seizures (FIASs and FBTCSs) and deep sleep had increases in slow wave delta (1-4 Hz) band power. However, when network measures were employed, we found that only FIASs and deep sleep exhibited an increase in delta segregation and a decrease in gamma segregation. Furthermore, we found that only patients with FIASs had reduced subcortical-to-neocortical functional connectivity with fMRI versus controls. Finally, our deep learning network demonstrated an area under the curve of .75 for detecting consciousness-impairing seizures. This study provides novel insights into ictal network measures in FASs, FIASs, and FBTCSs. Importantly, although both FIASs and FBTCSs result in loss of consciousness, our results suggest that ictal network changes in FIASs uniquely resemble those that occur during deep sleep. Our results may inform novel neuromodulation strategies for preservation of consciousness in epilepsy.

G-band traveling wave tube based on the elliptical pillar defected photonic crystal

In order to reduce the ohmic losses in the slow wave structure (SWS), an elliptical pillar defected photonic crystal waveguide (EPDPCW) is proposed as a SWS for the terahertz traveling wave tube (TWT). Compared with rectangular pillar defected photonic crystal waveguides (RPDPCW), the EPDPCW shows better high-frequency characteristics and lower ohmic losses. According to the particle-in-cell (PIC) results, in the frequency range of 188 GHz to 218 GHz, the saturated output power of EPDPCW is greater than 13.4 W, and the maximum saturated output power is 26.8 W at 196 GHz at a voltage of 9.78 kV and a beam current of 150 mA. Compared to the RPDPCW-TWT, the performance of the EPDPCW-TWT has been significantly improved.

Neural Signals Associated with Orienting Response and Arousal Inhibition in Concealed Information Test

Recent theory suggests that both the orienting response and arousal inhibition play roles in the effect of the concealed information test (CIT). However, the neural signatures associated with these two processes remain unclear. To address this issue, participants were motivated to either conceal or reveal crime-related stimulus during CIT while EEG was recorded. By using a temporal principal component analysis, we found that crime-related stimuli produced a larger early P3 than crime-irrelevant stimuli in both the conceal condition and reveal condition. This result suggests that this early P3 reflects an orienting response. In addition, we found that crime-related stimuli elicited a larger frontal negative slow wave than crime-irrelevant stimuli in the conceal condition but not the reveal condition, which suggests that the frontal negative slow wave reflects the arousal inhibition process. These results provide crucial evidence for understanding the neural basis underlying CIT.

Gastric slow-wave modulation via power-controlled, irrigated radio-frequency ablation.

Recently, radio-frequency ablation has been used to modulate slow-wave activity in the porcine stomach. Gastric ablation is, however, still in its infancy compared to its history in the cardiac field, and electrophysiological studies have been restricted to temperature-controlled, non-irrigated ablation. Power-controlled, irrigated ablation may improve lesion formation at lower catheter-tip temperatures that produce the desired localized conduction block. Power-controlled, irrigated radio-frequency ablation was performed on the gastric serosal surface of female weaner pigs (n = 5) invivo. Three combinations of power (10-15 W) and irrigation settings (2-5 mL min-1) were investigated. A total of 12 linear lesions were created (n = 4 for each combination). Slow waves were recorded before and after ablation using high-resolution electrical mapping. Irrigation maintained catheter-tip temperature below 50°C. Ablation induced a complete conduction block in 8/12 cases (4/4 for 10 W at 2 mL min-1, 1/4 for 10 W at 5 mL min-1, 3/4 for 15 W at 5 mL min-1). Blocks were characterized by a decrease in signal amplitude at the lesion site, along with changes in slow-wave propagation patterns, where slow waves terminated at and/or rotated around the edge of the lesion. Power-controlled, irrigated ablation can successfully modulate gastric slow-wave activity at a reduced catheter-tip temperature compared to temperature-controlled, non-irrigated ablation. Reducing the irrigation rate is more effective than increasing power for blocking slow-wave activity. These benefits suggest that irrigated ablation is a suitable option for further translation into a clinical intervention for gastric electrophysiology disorders.

Emergent effects of synaptic connectivity on the dynamics of global and local slow waves in a large-scale thalamocortical network model of the human brain.

Slow-wave sleep (SWS), characterized by slow oscillations (SOs, <1Hz) of alternating active and silent states in the thalamocortical network, is a primary brain state during Non-Rapid Eye Movement (NREM) sleep. In the last two decades, the traditional view of SWS as a global and uniform whole-brain state has been challenged by a growing body of evidence indicating that SO can be local and can coexist with wake-like activity. However, the mechanisms by which global and local SOs arise from micro-scale neuronal dynamics and network connectivity remain poorly understood. We developed a multi-scale, biophysically realistic human whole-brain thalamocortical network model capable of transitioning between the awake state and SWS, and we investigated the role of connectivity in the spatio-temporal dynamics of sleep SO. We found that the overall strength and a relative balance between long and short-range synaptic connections determined the network state. Importantly, for a range of synaptic strengths, the model demonstrated complex mixed SO states, where periods of synchronized global slow-wave activity were intermittent with the periods of asynchronous local slow-waves. An increase in the overall synaptic strength led to synchronized global SO, while a decrease in synaptic connectivity produced only local slow-waves that would not propagate beyond local areas. These results were compared to human data to validate probable models of biophysically realistic SO. The model producing mixed states provided the best match to the spatial coherence profile and the functional connectivity estimated from human subjects. These findings shed light on how the spatio-temporal properties of SO emerge from local and global cortical connectivity and provide a framework for further exploring the mechanisms and functions of SWS in health and disease.

Pulsed-field ablation: An alternative ablative method for gastric electrophysiological intervention.

Pulsed-field ablation (PFA) is an emerging ablative technology that has been used successfully to eliminate cardiac arrhythmias. As a non-thermal technique it has significant benefits over traditional radio-frequency ablation with improved target tissue specificity and reduced risk of adverse events during cardiac applications. We investigated whether PFA is safe for use in the stomach and whether it could modulate gastric slow waves. Female weaner pigs were fasted overnight before anesthesia was induced using tiletamine hydrochloride (50 mg mL-1) and zolazepam hydrochloride (50 mg mL-1) and maintained with propofol (Diprivan 2%, 0.2‑0.4 mg kg‑1 min‑1). Pulsed-field ablation was performed on their gastric serosa in vivo. Adjacent point lesions (n=2-4) were used to create a linear injury using bipolar pulsed-field ablation consisting of 40 pulses (10 Hz frequency, 0.1 ms pulse width, 1000 V amplitude). High-resolution electrical mapping defined baseline and post-ablation gastric slow-wave patterns. A validated five-point scale was used to evaluate tissue damage in hematoxylin and eosin stained images. Results indicated that PFA successfully induced complete conduction blocks in all cases, with lesions through the entire thickness of the gastric muscle layers. Consistent post-ablation slow-wave patterns emerged immediately following ablation and persisted over the study period. Pulsed-field ablation induces rapid conduction blocks as a tool to modulate slow-wave patterns, indicating it may be suitable as an alternative to radio-frequency ablation.

Attentional resource consumption of verbal-humor processing: An ERP study

As a high-demanding mental activity with both cognitive and emotional factors, verbal-humor processing consumes more attentional resources than non-humor processing, which has been demonstrated by behavioral studies, but little has been examined at a real-time scale. Based on the three-stage model (incongruity detection, incongruity resolution, and mirth), the current study used event-related potential (ERP) and event-related oscillation (ERO) to explore the attentional resource consumption of verbal-humor processing by employing a dual-task paradigm in which sentence comprehension (humorous, positive, neutral) was the primary task and arithmetical calculation (simple, difficult) was the secondary task.Participants’ (N=38) behavioral performance and ERP/ERO measures in two tasks were analyzed. ERP results of verbal-humor processing revealed significantly larger LAN, LLAN, and LPP activation, which indexed three stages. ERO results showed significant beta power changes in the detection stage and theta changes in the resolution and mirth stages. The behavioral data indicated that the Reaction Times (RTs) of the arithmetical task following verbal-humor processing were longer than those following non-humorous positive and neutral ones. The ERP results of arithmetical calculation found that the calculations following verbal-humor processing elicited significantly greater P2, P3b, and positive slow wave amplitudes than those following the other two processings, which reflected more resource allocation in the calculation to compensate for the resource preemption of verbal-humor processing. In addition, the calculation following positive sentence exhibited a greater ERP amplitude in the relatively early P2 time intervals than that following the neutral sentences. Collectively, the behavioral, ERP, and ERO results concurrently confirmed that verbal-humor processing consumed more attentional resources compared with non-humorous counterparts, and moreover, the comparison of ERP following humorous and positive sentences suggested that the processing of the cognitive factor consumes more attentional resources than the emotional factor although both factors play a role in the process.

Eurycoma longifolia (Tongkat Ali) supplementation enhances sleep and wake consolidation in wild-type, but not in narcoleptic mice.

Tongkat Ali (TA), also known as Eurycoma longifolia, has been used as a traditional herbal medicine for anti-aging, evidenced by clinical trials presenting the beneficial effects on energy, fatigue, and mood disturbance. We have recently shown that TA supplementation dose-dependently enhances the rest-activity pattern in C57BL/6 mice. Since destabilization of wakefulness and sleep is one of the typical symptoms of not only the elderly but also narcolepsy, we performed sleep analysis with and without dietary TA extract supplementation in middle-aged (10-12 months old) wild-type (WT) and narcoleptic DTA mice. We found that TA supplementation enhanced diurnal rhythms of locomotion and temperature in a time-of-day-dependent manner in WT mice but attenuated in DTA mice. In WT mice, TA supplementation consolidated wakefulness with a long bout duration and led to less entries into the sleep state during the active period, while it consolidated NREM sleep with long bout duration during the resting period. Neither disturbed sleep and wake cycles nor cataplexy was sufficiently improved in DTA mice. EEG spectral analysis revealed that TA supplementation enhanced slow wave activity (SWA) at both delta and low delta frequencies (0.5-4.0 and 0.5-2.0 Hz) during the light period, suggesting TA extract may induce vigilance during the active period, which then elicits a rebound effect during the resting period. Interestingly, DTA mice also slightly, but significantly, increased SWA at low frequencies during the light period. Taken together, our results suggest that TA supplementation enhances the Yin-Yang balance of sleep, temperature, and locomotion in WT mice, while its efficacy is limited in narcoleptic mice.

Diffraction of displaced Gaussian light beams on ultrasound in paratellurite crystals

The Bragg diffraction of displaced Gaussian light beams on a slow shear ultrasonic wave in paratellurite crystals, in which the beam energy is efficiently transferred from the zero diffraction order to the first, is investigated. It is established that circularly polarized light beams should be used to optimize the energy exchange of diffracted light beams in the considered geometry of acousto-optic interaction. It is shown that the diffracted beams have the form of displaced Gaussian beams, the spatial structure of which is determined by the displacement parameter of the incident beam and the ultrasound power.

Nonlinear analysis of ion‐acoustic solitary waves in an unmagnetized highly relativistic quantum plasma

AbstractThe present paper explores the dynamics of ion‐acoustic solitary waves (IASWs) within an unmagnetized, highly relativistic quantum plasma containing positive and negative ions alongside electrons, employing the quantum hydrodynamic model. The treatment accounts for the inertial characteristics of negative and positive ions, considering electrons as inertialess. The nonlinear nature of quantum IASWs is investigated through the derivation of the Korteweg–de Vries equation using the reductive perturbation method. The investigation highlights how wave propagation characteristics, whether compressive or rarefactive, are substantially modulated by several parameters, such as the quantum diffraction parameter , relativistic effects , equilibrium density , and ion mass ratio . The analysis identifies the existence of both slow and fast wave modes, heavily influenced by the relativistic parameters involved. Our findings have significant implications for the understanding of both laboratory and space plasmas, especially in contexts where negative ions are present.

Sleep oscillations related to memory consolidation during aromatases inhibitors for breast cancer

Aromatase inhibitors (AIs) are associated with sleep difficulties in breast cancer (BC) patients. Sleep is known to favor memory consolidation through the occurrence of specific oscillations, i.e., slow waves (SW) and sleep spindles, allowing a dialogue between prefrontal cortex and the hippocampus. Interestingly, neuroimaging studies in BC patients have consistently shown structural and functional modifications in these two brain regions. With the aim to evaluate sleep oscillations related to memory consolidation during AIs, we collected polysomnography data in BC patients treated (AI+, n = 17) or not (AI-, n = 17) with AIs compared to healthy controls (HC, n = 21). None of the patients had received chemotherapy and radiotherapy was finished since at least 6 months, that limit the confounding effects of other treatments than AIs. Fast and slow spindles were detected during sleep stage 2 at centro-parietal and frontal electrodes respectively. SW were detected at frontal electrodes during stage 3. Here, we show lower frontal SW densities in AI + patients compared to HC. These results concord with previous reports about frontal cortical alterations in cancer following AIs administration. Moreover, AI + patients tended to have lower spindle density at C4 electrode. Regression analyses showed that, in both patient groups, spindle density at C4 electrode explained a large variance of memory performances. Slow spindle characteristics did not differ between groups and sleep oscillations characteristics of AI- patients did not differ significantly from those of both AI + patients and HC. Overall, our results add to the compelling evidence of the systemic effects of AIs previously reported in animals, with deleterious effects on cortical activity during sleep and associated memory consolidation in the current study. There is thus a need to further investigate sleep modifications during AIs administration. Longitudinal studies are needed to confirm these findings and investigation in other cancers on this topic should be conducted.