Rhythmic Activity Research Articles

Molecular and Cellular Mechanisms of Motor Circuit Development.

Motor circuits represent the main output of the central nervous system and produce dynamic behaviors ranging from relatively simple rhythmic activities like swimming in fish and breathing in mammals to highly sophisticated dexterous movements in humans. Despite decades of research, the development and function of motor circuits remain poorly understood. Breakthroughs in the field recently provided new tools and tractable model systems that set the stage to discover the molecular mechanisms and circuit logic underlying motor control. Here, we describe recent advances from both vertebrate (mouse, frog) and invertebrate (nematode, fruit fly) systems on cellular and molecular mechanisms that enable motor circuits to develop and function and highlight conserved and divergent mechanisms necessary for motor circuit development.

Challenges and Approaches in the Study of Neural Entrainment.

When exposed to rhythmic stimulation, the human brain displays rhythmic activity across sensory modalities and regions. Given the ubiquity of this phenomenon, how sensory rhythms are transformed into neural rhythms remains surprisingly inconclusive. An influential model posits that endogenous oscillations entrain to external rhythms, thereby encoding environmental dynamics and shaping perception. However, research on neural entrainment faces multiple challenges, from ambiguous definitions to methodological difficulties when endogenous oscillations need to be identified and disentangled from other stimulus-related mechanisms that can lead to similar phase-locked responses. Yet, recent years have seen novel approaches to overcome these challenges, including computational modeling, insights from dynamical systems theory, sophisticated stimulus designs, and study of neuropsychological impairments. This review outlines key challenges in neural entrainment research, delineates state-of-the-art approaches, and integrates findings from human and animal neurophysiology to provide a broad perspective on the usefulness, validity, and constraints of oscillatory models in brain-environment interaction.

Effects of 8 weeks of rhythmic physical activity on gross motor movements in 4-5-year-olds: A randomized controlled trial

ObjectiveRhythmic physical activity holds promise for positively influencing the gross motor development of 4-5-year-old children, yet empirical research in this domain remains limited. This study aimed to investigate the effects of rhythmic physical activity on the gross motor development in children aged 4–5 years. MethodsFifty children aged 4–5 years were recruited and randomly assigned to either the intervention or control group. Both groups participated in a 10-week intervention program facilitated by a professional trainer, with support from numerous dedicated volunteers from reputable sports universities. This program comprised a one-week baseline assessment followed by 8 weeks of rhythmic physical activity training conducted three times per week. Gross motor performance was assessed using the PGMQ scale before and one week after the intervention. ResultsFollowing the 8-week intervention, the intervention group demonstrated significant enhancements in displacement ability, with notable improvements observed in. Specifically, the scores for running, sliding lateral transfer, leaping step, two-footed back-and-forth jump, and total displacement ability showed significant increases (P < 0.05). Moreover, the total scores for running, standing long jump, sliding lateral transfer, leaping step, two-footed back-and-forth jump, and displacement ability exhibited significant differences between the intervention and control groups (P < 0.05). Regarding manipulative ability, the intervention group showed significant increases in scores for over-the-shoulder throwing, two-handed catching, and kicking (P < 0.05). Moreover, there were significant differences between groups in the scores for two-handed catching and kicking (P < 0.05). Concerning balance ability, the intervention group exhibited significant improvements in scores for single-leg stand, double-leg stand, and total balance ability (P < 0.05). No significant differences were observed in any of the indices within the control group (P > 0.05). The two-way repeated measures ANOVA of intervention × time revealed significant differences in scores for running, sliding lateral movement, leaping step, jumping back and forth with both feet, leading ability, kicking, manipulation ability, single-leg stand, double-leg stand, balance ability, and gross motor scores (P < 0.05). ConclusionsThis study underscores the beneficial impact of engaging in eight weeks of rhythmic physical activity on the gross motor development of 4-5-year-olds. Furthermore, the improvements in gross motor development achieved through rhythmic physical activity may surpass those obtained through general physical activity.

Ultradian rhythms of activity in a wild subterranean rodent.

Many animals adapt their activity patterns to the best environmental conditions using daily rhythms. African mole-rats are among the mammals that have become models for studying how these rhythms can be entrained by light or temperature in experimental laboratory studies. However, it is unclear whether they exhibit similar circadian rhythms in their natural lightless, subterranean environment. In this study, we used biologging to investigate the activity rhythms of wild, highveld mole-rats. We show that their activity cycle exhibited an ultradian rhythm with a length between 4 and 8 h. On an individual level, mole-rats displayed about five activity bouts per day, occurring at various times during the day and night. On a population level, activity peaked in the afternoon, coinciding with the peak in ambient temperature. Our research suggests that wild subterranean mammals, which experience reduced environmental variation, are unlikely to show clear circadian rhythmicity in activity patterns. Instead, activity periods are distributed over several bouts throughout the day and night, and activity coincides with the peak in daily temperature. We propose that ultradian rhythms in activity may be more common than previously thought and discuss how physiological processes may generate differences in periodicity between laboratory and wild populations.

Utility of CT perfusion in seizures and rhythmic and periodic patterns

ObjectiveCT hyper-perfusion has been reported in non-convulsive status epilepticus (NCSE), while its occurrence and relevance after single seizures or with rhythmic and periodic patterns (RPPs) that lie along the ictal-interictal continuum (IIC), remain unclear. The goal of the study is to assess the role of CT perfusion (CTP) in diagnosing patients with clinical seizures, subclinical seizures, or RPPs that lie along the IIC, to help in the clinical assessment of these entities. MethodsWe retrospectively reviewed inpatients who underwent a CTP and an EEG within 6 h of each other. CTP and EEGs were blindly reviewed independent of electronic medical records. ResultsOut of 103 patients, 15 patients (15 %) demonstrated hyper-perfusion, 40 patients (39 %) had hypo-perfusion, while 48 patients (47 %) had normal CTP. Patients with focal CTP hyperperfusion were more likely to have clinical seizures, electrographic seizures, and/or lateralized rhythmic periodic patterns (RPPs) compared to those without CTP hyperperfusion. Focal CTP hyper-perfusion had 34 % sensitivity and 96 % specificity for identifying patients with clinical seizures, and a 40 % sensitivity and 92 % specificity for identifying patients with electrographic seizures or lateralized RPP. Although the numbers were small, none of the patients with generalized periodic discharges or generalized rhythmic delta activity had CTP hyper-perfusion. ConclusionsFocal CTP hyper-perfusion has low sensitivity but high specificity for identifying patients with seizures and lateralized RPPs, and may be considered in the clinical assessment of patients where the clinical information are unclear or insufficient. SignificanceThe presence of CTP hyper-perfusion should alert the physician to the possibility of an ictal related etiology accounting for the patient’s symptoms.

Patterns of ictal surface EEG in occipital seizures: A simultaneous scalp and intracerebral recording study

ObjectiveTo describe the ictal scalp EEG patterns of occipital seizures (OS) and their spatiotemporal correlations with intracerebral occipital ictal discharges derived from simultaneous SEEG-EEG recordings. MethodsPatients with SEEG confirmed OS (14 OS from 8 patients) were selected from an epilepsy surgery center and were monitored 3–10 days using simultaneous scalp EEG and SEEG recordings. ResultsOn scalp EEG, the most common onset patterns were background activity suppression (28.6 %) and high amplitude slow wave corresponding to intracerebral DC-shift (28.6 %) and occurred with a median delay of 0 s after intra-cerebral onset. The initial discharge involved occipital electrodes in only 50 % of the seizures (7/14) with additional basal temporal (8/14) or parietal electrodes (5/14). The onset was ipsilateral to the intra-cerebral onset zone in 71.4 % of seizures and bilateral in the remaining (28.6 %). The most common propagation pattern was either unilateral (50 %) or bilateral (50 %) and a rhythmic slow activity (66.7 %). Different OS subtypes display distinct scalp EEG patterns. ConclusionScalp EEG accurately determines intra-cerebral seizure onset time in OS and has good lateralizing value. However, initial scalp modification does not always involves occipital electrodes and the second modification is well lateralizing in only 50 % of seizures. SignificanceThis study describes will help clinicians to better identify OS during video EEG and better plan intra-cerebral explorations for epilepsy surgery.

Ketogenic Diet as a Therapeutic Intervention for Doose Syndrome: A Case Report and Review of Current Evidence

Epilepsy with myoclonic-atonic seizures, also known as Doose syndrome or myoclonic–astatic epilepsy (MAE), represents a challenging pediatric epilepsy syndrome, initially described by Doose et al. in 1970. MAE accounts for 1%–2.2% of juvenile-onset epilepsy cases, characterized by normal early development, followed by seizure onset between 7 months and 6 years. Seizure types include myoclonic, myoclonic-atonic, generalized tonic–clonic, and atypical absences, often accompanied by nonconvulsive status epilepticus. Electroencephalogram typically shows parietal-dominant rhythmic theta activity or a posterior 4 Hz pattern. While conventional antiseizure medications (ASMs) offer some efficacy, outcomes vary widely, and up to 50% of patients may experience refractory seizures and poor intellectual outcomes. The ketogenic diet (KD), a high-fat, low-carbohydrate diet inducing ketosis, has shown promise in reducing seizure frequency and severity in refractory epilepsy, including MAE. This case report describes a successful outcome with a South Indian style KD in a 3-year-old boy with Doose syndrome presenting with 20–25 daily head drop seizures despite multiple ASMs and steroid therapy. Initiation of a home-based KD utilizing traditional household ingredients significantly reduced seizure frequency by 60% within 1 month and 80% within 2 months and was 100% seizure-free in 3rd month following KD, alongside developmental improvements. The KD was well-tolerated, with improved nutritional status. This case underscores KD’s potential as a viable complementary therapy for MAE, emphasizing the need for ongoing parental support and supervision to ensure dietary adherence and optimize outcomes. It is commonly believed that the KD is challenging for the South Indian population to follow due to the high carbohydrate content in South Indian cuisine. However, this case demonstrates that a KD can indeed be tailored around South Indian dishes, highlighting the uniqueness of this approach. When the diet is customized to consider a child’s dietary habits, culture, and cuisine, it becomes easier to follow over the long term, leading to effective seizure control. Further research is necessary to refine dietary protocols and evaluate long-term efficacy in MAE management.

Sleep, Sleep Apnea, and Fatigue in People Living With HIV

Background: People living with HIV (PLWH) often report fatigue even when viral load is suppressed. Obstructive sleep apnea (OSA), which is often associated with fatigue, is common in PLWH, but whether OSA explains fatigue in this population is unknown. Setting: Academic university-affiliated HIV and Sleep Medicine Clinics. Methods: PLWH, aged 18–65 years, with a body mass index of 20–35 kg/m2 and viral suppression (RNA &lt;200 copies per mL), were recruited to undergo daytime questionnaires, including the Functional Assessment of Chronic Illness Therapy Fatigue Scale and Epworth Sleepiness Scale, 7 days of actigraphy (to determine daily sleep duration and activity amplitude and rhythms), and an in-laboratory polysomnography to assess for the presence and severity of OSA. Results: Of 120 subjects with evaluable data, 90 (75%) had OSA using the American Academy of Sleep Medicine 3% desaturation or arousal criteria, with an apnea–hypopnea index &gt;5/h. There was no difference in Functional Assessment of Chronic Illness Therapy scores between those with and without OSA, although those with OSA did report more daytime sleepiness as measured using the Epworth Sleepiness Scale. In a multivariable model, predictors of fatigue included more variable daily sleep durations and decreased mean activity counts. Sleepiness was predicted by the presence of OSA. Conclusion: OSA was very common in our cohort of PLWH, with those with OSA reporting more sleepiness but not more fatigue. Variability in sleep duration was associated with increased fatigue. Further study is needed to determine if treatment of OSA, or an emphasis on sleep consistency and timing, improves symptoms of fatigue in PLWH.

Properties of rhythmogenic currents in spinal Shox2 interneurons across postnatal development.

Locomotor behaviors are performed by organisms throughout life, despite developmental changes in cellular properties, neural connectivity, and biomechanics. The basic rhythmic activity in the central nervous system that underlies locomotion is thought to be generated via a complex balance between network and intrinsic cellular properties. Within mature mammalian spinal locomotor circuitry, we have yet to determine which properties of spinal interneurons (INs) are critical to rhythmogenesis and how they change during development. Here, we combined whole cell patch clamp recordings, immunohistochemistry, and RNAscope targeting lumbar Shox2 INs in mice, which are known to be involved in locomotor rhythm generation. We focused on the properties of putatively rhythmogenic ionic currents and the expression of corresponding ion channels across postnatal time points in mice. We show that subsets of Shox2 INs display voltage-sensitive conductances, in addition to respective ion channels, which may contribute to or shape rhythmic bursting. Persistent inward currents, M-type potassium currents, slow afterhyperpolarization, and T-type calcium currents are enhanced with age. In contrast, the hyperpolarization-activated and A-type potassium currents were either found with low prevalence in subsets of neonatal, juvenile, and adult Shox2 INs or did not developmentally change. We show that Shox2 INs become more electrophysiologically diverse by juvenile and adult ages, when locomotor behavior is weight-bearing. These results suggest a developmental shift in the magnitude of rhythmogenic ionic currents and the expression of corresponding ion channels that may be important for mature, weight-bearing locomotor behavior.

People with HIV exhibit spectrally distinct patterns of rhythmic cortical activity serving cognitive flexibility

Despite effective antiretroviral therapy, cognitive impairment remains prevalent among people with HIV (PWH) and decrements in executive function are particularly prominent. One component of executive function is cognitive flexibility, which integrates a variety of executive functions to dynamically adapt one's behavior in response to changing contextual demands. Though substantial work has illuminated HIV-related aberrations in brain function, it remains unclear how the neural oscillatory dynamics serving cognitive flexibility are affected by HIV-related alterations in neural functioning. Herein, 149 participants (PWH: 74; seronegative controls: 75) between the ages of 29–76 years completed a perceptual feature matching task that probes cognitive flexibility during high-density magnetoencephalography (MEG). Neural responses were decomposed into the time-frequency domain and significant oscillatory responses in the theta (4–8 Hz), alpha (10–16 Hz), and gamma (74–98 Hz) spectral windows were imaged using a beamforming approach. Whole-brain voxel-wise comparisons were then conducted on these dynamic functional maps to identify HIV-related differences in the neural oscillatory dynamics supporting cognitive flexibility. Our findings indicated group differences in alpha oscillatory activity in the cingulo-opercular cortices, and differences in gamma activity were found in the cerebellum. Across all participants, alpha and gamma activity in these regions were associated with performance on the cognitive flexibility task. Further, PWH who had been treated with antiretroviral therapy for a longer duration and those with higher current CD4 counts had alpha responses that more closely resembled those of seronegative controls, suggesting that optimal clinical management of HIV infection is associated with preserved neural dynamics supporting cognitive flexibility.

Reduced Cortical Excitability is Associated with Cognitive Symptoms in Concussed Adolescent Football Players.

American tackle football is associated with high rates of concussion, leading to neurophysiological disturbances and debilitating clinical symptoms. Previous investigations of the neurophysiological effects of concussion have largely ignored aperiodic neurophysiological activity. We examined whether concussion during a season of high school football is related to changes in aperiodic and periodic neurophysiological activity and whether any such changes are associated with clinical outcomes. Pre- and post-season resting-state MEG data were collected from 91 high school football players, of whom 10 were diagnosed with concussion. Data were source-imaged, frequency-transformed and parameterized, and linear mixed models were used to examine effects of concussion on pre-to-post-season changes in neurophysiological activity. Scores on the Post-Concussive Symptom Inventory were correlated with pre-to-post-season neurophysiological changes to determine their clinical relevance. Concussion was associated with increased aperiodic exponents in superior frontal cortices, indicating a relative reduction in cortical excitability. This slowing of aperiodic neurophysiology mediated concussion effects on raw delta and gamma power and was associated with worse cognitive concerns across participants. Pre-to-post-season changes in aperiodic-corrected alpha and theta rhythmic activity were also decreased in posterior cortices in instances of concussion. These findings indicate that concussion alters both the excitability and rhythmic signaling of the cortex, with differing spatial topographies and implications for clinical symptoms.

Clinical Spectrum and EEG Findings in Patients with Suspected Non-Convulsive Status Epilepticus

This study looked at the clinical spectrum as well as EEG results to help diagnose and treat patients with probable non-convulsive status epilepticus (NCSE). Patients were classified into two groups based on the degree of NCSE: mild to moderate and severe and their medical records revealed evidence of epilepsy in the form of rhythmic delta activity and localized slowing or widespread spike-and-wave (WSW) discharges in EEG. Severe NCSE was associated with increased antiepileptic drug use (90 vs 80%), longer treatment duration (10 vs 7days), and higher critical care unit admissions (40vs25%) (p&lt;0.05). EEG data showed a significant increase in the frequency of generalized spike-and-wave discharges (45 vs 30%) and localized slowing (32vs20%) (p&lt;0.05). Furthermore, these patients' neurological recovery was worse and they remained in the hospital longer. Finally, the severity of the NCSE and poor clinical outcomes were substantially linked to specific EEG patterns, especially localized slowing and WSW discharges.

The posterior hypothalamic area as an independent generator of rhythmic theta oscillatory activity

Theta rhythm is one of the most prominent examples of rhythmic oscillatory activity in mammalian brain and it is generated mainly in structures of the limbic cortex, including the hippocampal formation. In the 1970s it was shown that theta rhythm may be also recorded in diencephalic region including the posterior hypothalamic nuclei and supramammillary nucleus, together considered as the posterior hypothalamic area (PHa). For decades it was stated that local posterior hypothalamic oscillatory activity is controlled by the descending inputs going to the PHa from the septohippocampal system. However, the latest studies indicated that theta rhythm can be recorded in deafferented PHa in vitro preparations which indicates that the posterior hypothalamic area should be considered as an independent of the other brain structures theta generator. In subsequent research the neurochemical and cellular basis of PHa theta were examined in both in vivo and in vitro conditions. In the light of multiple evidence obtained in these studies, it is the author’s intent to summarize the data concerning the role of the posterior hypothalamic area in hippocampal theta rhythm generation as well as the ability of that brain structure to independently generate theta rhythmicity.

Scheduled feeding improves behavioral outcomes and reduces inflammation in a mouse model of Fragile X syndrome.

Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by the abnormal expansion of CGG repeats in the fragile X mental retardation 1 (FMR1) gene. Many FXS patients experience sleep disruptions, and we sought to explore these symptoms along with the possible benefits of a scheduled feeding intervention using the Fmr1 knockout (KO) mouse model. These mutants displayed clear evidence for sleep and circadian disturbances including delay in the onset of sleep and fragmented activity rhythms with increases in cycle-to-cycle variability. The Fmr1 KO mice exhibited deficits in their circadian behavioral response to light with reduced masking, longer time to resetting to shifts in the LD cycle, altered synchronization to a skeleton photoperiod and lower magnitude light-induced phase shifts of activity rhythms. Investigation of the retinal input to the surprachiasmatic nucleus (SCN) with the neurotracer cholera toxin (β subunit) and quantification of the light-evoked cFos expression in the SCN revealed an abnormal retinal innervation of the SCN in the Fmr1 KO, providing a possible mechanistic explanation for the observed behavioral deficits. Interestingly, disruptions in social and repetitive behavior correlated with sleep duration and fragmentation. Understanding the nature of the deficits, we decided to apply a scheduled feeding regimen (6-hr/18-hr feed/fast cycle) as a circadian-based strategy to boast circadian rhythms independently of light. This intervention significantly improved the activity rhythms and sleep in the mutants. Strikingly, the scheduled feeding ameliorated social interactions and reduced repetitive behaviors as well as the levels of Interferon-gamma and Interleukin-12 in the Fmr1 KO mutants, suggesting that timed eating may be an effective way to reduce inflammation. Collectively, this work adds support to efforts to develop circadian based interventions to help with symptoms of neurodevelopmental disorders.

Associations between neuromelanin depletion and cortical rhythmic activity in Parkinson's disease.

Parkinson's disease (PD) is marked by the death of neuromelanin-rich dopaminergic and noradrenergic cells in the substantia nigra (SN) and the locus coeruleus (LC), respectively, resulting in motor and cognitive impairments. While SN dopamine dysfunction has clear neurophysiological effects, the association of reduced LC norepinephrine signaling with brain activity in PD remains to be established. We used neuromelanin-sensitive T1-weighted MRI (NPD = 58; NHC = 27) and task-free magnetoencephalography (NPD = 58; NHC = 65) to identify neuropathophysiological factors related to the degeneration of the LC and SN in patients with PD. We found pathological increases in rhythmic alpha (8-12 Hz) activity in patients with decreased LC neuromelanin, with a stronger association in patients with worse attentional impairments. This negative alpha-LC neuromelanin relationship is strongest in fronto-motor cortices, where alpha activity is inversely related to attention scores. Using neurochemical colocalization analyses with normative atlases of neurotransmitter transporters, we also show that this effect is more pronounced in regions with high densities of norepinephrine transporters. These observations support a noradrenergic association between LC integrity and alpha band activity. Our data also show that rhythmic beta (15-29 Hz) activity in the left somato-motor cortex decreases with lower levels of SN neuromelanin; the same regions where beta activity reflects axial motor symptoms. Together, our findings clarify the association of well-documented alterations of rhythmic neurophysiology in PD with cortical and subcortical neurochemical systems. Specifically, attention-related alpha activity is related to dysfunction of the noradrenergic system, and beta activity with relevance to motor impairments reflects dopaminergic dysfunction.

Neuromodulator-induced temperature robustness in a motor pattern: a comparative study between two decapod crustaceans.

While temperature fluctuations pose significant challenges to the nervous system, many vital neuronal systems in poikilothermic animals function over a broad temperature range. Using the gastric mill pattern generator in the Jonah crab, we previously demonstrated that temperature-induced increases in leak conductance disrupt neuronal function and that neuropeptide modulation provides thermal protection. Here, we show that neuropeptide modulation also increases temperature robustness in Dungeness and green crabs. As in Jonah crabs, higher temperatures increased leak conductance in both species' pattern-generating lateral gastric neuron and terminated rhythmic gastric mill activity. Likewise, increasing descending modulatory projection neuron activity or neuropeptide transmitter application rescued rhythms at elevated temperatures. However, decreasing input resistance using dynamic clamp only restored the rhythm in half of the experiments. Thus, neuropeptide modulation increased temperature robustness in both species, demonstrating that neuropeptide-mediated temperature compensation is not limited to one species, although the underlying cellular compensation mechanisms may be distinct.

Snow Leopard (Panthera uncia) Activity Patterns Using Camera Traps in the Qilian Mountain National Park (Qinghai Area), China.

In recent years, there has been growing concern about the condition of snow leopards. The snow leopard (Panthera uncia), an apex predator of alpine ecosystems, is essential for the structural and functional stability of ecosystems. Monitoring of snow leopards' activity patterns based on camera traps in the Qilian Mountain National Park (Qinghai area) between August 2020 to October 2023 was performed. The results showed that autumn is the peak period of snow leopard activity, especially in September when the frequency of activity is the highest, and there is one peak in the frequency of snow leopard daily activity in the time period of 18:00-22:00, while the highest overlap of the daily activity curves of snow leopards in different months was from spring to autumn (Δ = 0.97), and there were significant differences in diurnal activity rhythm between spring and autumn (p = 0.002). Snow leopards prefer sunny days, and they tend to be active at temperatures of -10-9 °C. Our research aimed to uncover the activity patterns of snow leopards at different scales within the study area and provide data for further studies on snow leopards and other wildlife by researchers. This study can be used to gain a comprehensive understanding of the ecological characteristics of snow leopards and to assess their habitats, and it will also serve as a reference for the local wildlife management authorities in formulating snow leopard conservation measures.

Environmental Light Controls the Daily Organization of Breathing by Activating Brn3b-expressing Intrinsically Photosensitive Retinal Ganglion Cells in Mice.

Rhythmic, daily fluctuations in minute ventilation are controlled by the endogenous circadian clock located in the suprachiasmatic nucleus (SCN). While light serves as a potent synchronizer for the SCN, it also influences physiology and behavior by activating Brn3b-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs). It is currently unclear the extent to which the external light environment shapes daily ventilatory patterns independent of the SCN. To determine the relative influence of environmental light versus circadian timing on the organization of daily rhythms in minute ventilation, we used whole-body plethysmography to measure the breathing of mice housed on a non-entraining T28 cycle (14 h light:14 h dark). Using this protocol, we found that minute ventilation exhibits a ~28-h rhythm with a peak at dark onset that coincides with the light:dark cycle and the animals' locomotor activity. To determine if this 28-h rhythm in minute ventilation was mediated by Brn3b-expressing ipRGCs, we measured the breathing of Brn3bDTA mice housed under the T28 cycle. Brn3bDTA mice lack the Brn3b-expressing ipRGCs that project to many non-SCN brain regions. We found that despite rhythmic light cues occurring on a 28-h basis, Brn3bDTA mice exhibited 24-h rhythms in minute ventilation, locomotor activity, and core body temperature consistent with organization by the SCN. The 24-h minute ventilation rhythm of Brn3bDTA mice was found to be driven predominantly by tidal volume rather than respiratory rate. These data indicate that the external light:dark cycle can directly drive daily patterns in minute ventilation by way of Brn3b-expressing ipRGCs. In addition, these data strongly suggest that the activation of Brn3b-expressing ipRGCs principally organizes daily patterns in breathing and locomotor activity when light:dark cues are presented in opposition to endogenous clock timing.

Association between sleep bruxism and snoring in adults: An observational study

ObjectiveThis study evaluated the association between sleep bruxism and snoring. Additionally, the associations between sleep bruxism and age, sex, body mass index, sleep structure, sleep quality, and sleepiness were evaluated. MethodsAdults suspected of having sleep disorders (n = 61) underwent single-night video polysomnography according to the American Academy of Sleep Medicine criteria. Validated questionnaires were used to assess sleepiness and sleep quality, and clinical examinations were performed to document weight and height. Jamovi software was used for statistical analysis. Logistic regression analyses of the different sleep stages—REM sleep, NREM sleep, and total sleep time—were conducted. ResultsNo association was found between sleep bruxism and snoring (P > 0.31), with a small effect size (V = 0.171). However, the snore index was found to influence the rhythmic masticatory muscle activity index during REM sleep, with an odds ratio of 1.018 (95 % CI: 1.005 to 1.03; P = 0.05). Moreover, logistic regression showed that the desaturation index presented an odds ratio of 5.01 (95 % CI: 0.96 to 26.13; p = 0.056), with a medium effect size (>3.5). Sleep bruxism was not associated with age, sex, body mass index, or other sleep variables. ConclusionSnoring appears to be associated with bruxism during REM sleep. No associations were found between sleep bruxism and sex, age, or body mass index. This lack of association underscores the complexity of sleep bruxism and snoring and highlights the need for further research. Concerning sleep architecture, only desaturation episodes were associated with bruxism during REM sleep. Neither sleep quality nor sleepiness was associated with sleep bruxism.

Dynamics of Food Passing through the Digestive Tract in the Nocturnal Rodent Meriones crassus as a Response to the Rhythm of Feeding Activity

Dynamics of Food Passing through the Digestive Tract in the Nocturnal Rodent Meriones crassus as a Response to the Rhythm of Feeding Activity