Noribogaine acute administration in rats promotes wakefulness and suppresses REM 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 but with a distinct pharmacological profile, making this drug a promising therapeutic candidate. Therefore, we still ignore whether the sleep/wake alterations depend on ibogaine or its principal metabolite noribogaine. 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, similar to our previous results reported for ibogaine administration. Thus, we shed new evidence on the mechanisms by which iboga alkaloids work in the brain.

Sleep disrupts complex spiking dynamics in the neocortex and hippocampus.

Neuronal interactions give rise to complex dynamics in cortical networks, often described in terms of the diversity of activity patterns observed in a neural signal. Interestingly, the complexity of spontaneous electroencephalographic signals decreases during slow-wave sleep (SWS); however, the underlying neural mechanisms remain elusive. Here, we analyse in-vivo recordings from neocortical and hippocampal neuronal populations in rats and show that the complexity decrease is due to the emergence of synchronous neuronal DOWN states. Namely, we find that DOWN states during SWS force the population activity to be more recurrent, deterministic, and less random than during REM sleep or wakefulness, which, in turn, leads to less complex field recordings. Importantly, when we exclude DOWN states from the analysis, the recordings during wakefulness and sleep become indistinguishable: the spiking activity in all the states collapses to a common scaling. We complement these results by implementing a critical branching model of the cortex, which shows that inducing DOWN states to only a percentage of neurons is enough to generate a decrease in complexity that replicates SWS.

Selection of stimulus parameters for enhancing slow wave sleep events with a neural-field theory thalamocortical model.

Slow-wave sleep cortical brain activity, conformed by slow-oscillations and sleep spindles, plays a key role in memory consolidation. The increase of the power of the slow-wave events, obtained by auditory sensory stimulation, positively correlates with memory consolidation performance. However, little is known about the experimental protocol maximizing this effect, which could be induced by the power of slow-oscillation, the number of sleep spindles, or the timing of both events' co-occurrence. Using a mean-field model of thalamocortical activity, we studied the effect of several stimulation protocols, varying the pulse shape, duration, amplitude, and frequency, as well as a target-phase using a closed-loop approach. We evaluated the effect of these parameters on slow-oscillations (SO) and sleep-spindles (SP), considering: (i) the power at the frequency bands of interest, (ii) the number of SO and SP, (iii) co-occurrences between SO and SP, and (iv) synchronization of SP with the up-peak of the SO. The first three targets are maximized using a decreasing ramp pulse with a pulse duration of 50 ms. Also, we observed a reduction in the number of SO when increasing the stimulus energy by rising its amplitude. To assess the target-phase parameter, we applied closed-loop stimulation at 0°, 45°, and 90° of the phase of the narrow-band filtered ongoing activity, at 0.85 Hz as central frequency. The 0° stimulation produces better results in the power and number of SO and SP than the rhythmic or random stimulation. On the other hand, stimulating at 45° or 90° change the timing distribution of spindles centers but with fewer co-occurrences than rhythmic and 0° phase. Finally, we propose the application of closed-loop stimulation at the rising zero-cross point using pulses with a decreasing ramp shape and 50 ms of duration for future experimental work.

Treatment Practices and Outcomes in Continuous Spike and Wave during Slow Wave Sleep: A Multicenter Collaboration.

OBJECTIVES: To determine how continuous spike and wave during slow wave sleep (CSWS) is currently managed and to compare the effectiveness of current treatment strategies using a database from 11 pediatric epilepsy centers in the US. STUDY DESIGN: This retrospective study gathered information on baseline clinical characteristics, CSWS etiology, and treatment(s) in consecutive patients seen between 2014 and 2016 at 11 epilepsy referral centers. Treatments were categorized as benzodiazepines, steroids, other antiseizure medications (ASMs), or other therapies. Two measures of treatment response (clinical improvement as noted by the treating physician; and electroencephalography improvement) were compared across therapies, controlling for baseline variables. RESULTS: Eighty-one children underwent 153 treatment trials during the study period (68 trials of benzodiazepines, 25 of steroids, 45 of ASMs, 14 of other therapies). Children most frequently received benzodiazepines (62%) or ASMs (27%) as first line therapy. Treatment choice did not differ based on baseline clinical variables, nor did these variables correlate with outcome. After adjusting for baseline variables, children had a greater odds of clinical improvement with benzodiazepines (OR 3.32, 95%CI 1.57-7.04, P = .002) or steroids (OR 4.04, 95%CI 1.41-11.59, P = .01) than with ASMs and a greater odds of electroencephalography improvement after steroids (OR 3.36, 95% CI 1.09-10.33, P = .03) than after ASMs. CONCLUSIONS: Benzodiazepines and ASMs are the most frequent initial therapy prescribed for CSWS in the US. Our data suggests that ASMs are inferior to benzodiazepines and steroids and support earlier use of these therapies. Multicenter prospective studies that rigorously assess treatment protocols and outcomes are needed.

Hijacking of hippocampal-cortical oscillatory coupling during sleep in temporal lobe epilepsy.

Memory impairment is the most common cognitive deficit in patients with temporal lobe epilepsy (TLE). This type of epilepsy is currently regarded as a network disease because of its brain-wide alterations in functional connectivity between temporal and extra-temporal regions. In patients with TLE, network dysfunctions can be observed during ictal states, but are also described interictally during rest or sleep. Here, we examined the available literature supporting the hypothesis that hippocampal-cortical coupling during sleep is hijacked in TLE. First, we look at studies showing that the coordination between hippocampal sharp-wave ripples (100-200 Hz), corticothalamic spindles (9-16 Hz), and cortical delta waves (1-4 Hz) during nonrapid eye movement (NREM) sleep is critical for spatial memory consolidation. Then, we reviewed studies showing that animal models of TLE display precise coordination between hippocampal interictal epileptiform discharges (IEDs) and spindle oscillations in the prefrontal cortex. This aberrant oscillatory coupling seems to surpass the physiological ripple-delta-spindle coordination, which could underlie memory consolidation impairments. We also discuss the role of rapid eye movement (REM) sleep for local synaptic plasticity and memory. Sleep episodes of REM provide windows of opportunity for reactivation of expression of immediate early genes (i.e., zif-268 and Arc). Besides, hippocampal theta oscillations during REM sleep seem to be critical for memory consolidation of novel object place recognition task. However, it is still unclear which extend this particular phase of sleep is affected in TLE. In this context, we show some preliminary results from our group, suggesting that hippocampal theta-gamma phase-amplitude coupling is exacerbated during REM in a model of basolateral amygdala fast kindling. In conclusion, there is an increasing body of evidence suggesting that circuits responsible for memory consolidation during sleep seem to be gradually coopted and degraded in TLE. This article is part of the Special Issue "NEWroscience 2018".

Disruption of neocortical synchronisation during slow-wave sleep in the rotenone model of Parkinson's disease.

Parkinson's disease motor dysfunctions are associated with improperly organised neural oscillatory activity. The presence of such disruption at the early stages of the disease in which altered sleep is one of the main features could be a relevant predictive feature. Based on this, we aimed to investigate the neocortical synchronisation dynamics during slow-wave sleep (SWS) in the rotenone model of Parkinson's disease. After rotenone administration within the substantia nigra pars compacta, one group of male Wistar rats underwent sleep-wake recording. Considering the association between SWS oscillatory activity and memory consolidation, another group of rats underwent a memory test. The fine temporal structure of synchronisation dynamics was evaluated by a recently developed technique called first return map. We observed that rotenone administration decreased the time spent in SWS and altered the power spectrum within different frequency bands, whilst it increased the transition rate from a synchronised to desynchronised state. This neurotoxin also increased the probability of longer and decreased the probability of shorter desynchronisation events. At the same time, we observed impairment in object recognition memory. These findings depict an electrophysiological fingerprint represented by a disruption in the typical oscillatory activity within the neocortex at the early stages of Parkinson's disease, concomitant with a decrease in the time spent in SWS and impairment in recognition memory.

El sueño en el crustáceo acocil.

Sleep is defined as a state of unconsciousness, reduced locomotive activity and rapid awakening, and is well established in mammals, birds, reptiles and teleosts. Commonly, it is also defined with electrical records (electroencephalogram), which are only well established in mammals and to some extent in birds. However, sleep states similar to those of mammals, except for electrical criteria, appear to occur in some invertebrates. Currently, the most compelling evidence of sleep in invertebrates has been obtained in the crayfish. In mammals, sleep is characterized by a brain state that is different from that of wakefulness, which includes a change to slow waves that has not been observed in Drosophila or bees. Herein, we show that the crayfish enters a brain state with a high threshold to vibratory stimuli, accompanied by a form of slow wave activity in the brain, quite different from that of wakefulness. Therefore, the crayfish can enter a state of sleep that is comparable to that of mammals.

El sueño es definido como un estado de inconciencia, reducción en la actividad locomotora y despertar rápido, el cual está bien identificado en mamíferos, aves, reptiles y teleosteos. Comúnmente también es definido con registros eléctricos (electroencefalograma), los cuales solo están bien establecidos en mamíferos y, en cierta manera, en aves. Sin embargo, estados de sueño similares a los de mamíferos, excepto por los criterios eléctricos, parecen ocurrir en algunos invertebrados. Actualmente la mejor evidencia de sueño en invertebrados ha sido obtenida en el acocil. En los mamíferos, el sueño se caracteriza por un estado cerebral diferente al de la vigilia, que incluye un cambio a ondas lentas, lo que no se ha visto en Drosophila o abejas. Aquí mostramos que el acocil tiene un estado cerebral con umbral elevado a estímulos vibratorios, acompañado por una forma de actividad de ondas lentas en el cerebro, muy diferente al de la vigilia. Por lo tanto, el acocil puede experimentar un estado de sueño comparable al de los mamíferos.

The avalanche-like behaviour of large-scale haemodynamic activity from wakefulness to deep sleep.

Increasing evidence suggests that responsiveness is associated with critical or near-critical cortical dynamics, which exhibit scale-free cascades of spatio-temporal activity. These cascades, or 'avalanches', have been detected at multiple scales, from in vitro and in vivo microcircuits to voltage imaging and brain-wide functional magnetic resonance imaging (fMRI) recordings. Criticality endows the cortex with certain information-processing capacities postulated as necessary for conscious wakefulness, yet it remains unknown how unresponsiveness impacts on the avalanche-like behaviour of large-scale human haemodynamic activity. We observed a scale-free hierarchy of co-activated connected clusters by applying a point-process transformation to fMRI data recorded during wakefulness and non-rapid eye movement (NREM) sleep. Maximum-likelihood estimates revealed a significant effect of sleep stage on the scaling parameters of the cluster size power-law distributions. Post hoc statistical tests showed that differences were maximal between wakefulness and N2 sleep. These results were robust against spatial coarse graining, fitting alternative statistical models and different point-process thresholds, and disappeared upon phase shuffling the fMRI time series. Evoked neural bistabilities preventing arousals during N2 sleep do not suffice to explain these differences, which point towards changes in the intrinsic dynamics of the brain that could be necessary to consolidate a state of deep unresponsiveness.

Evolución atípica del síndrome de Panayiotopoulos a síndrome de punta-ondas continuas durante el sueño lento / Atypical evolution of Panayiotopoulos syndrome to continuous spikes and wave's syndrome during slow sleep

Introducción: Las epilepsias focales idiopáticas constituyen uno de los grupos de epilepsias más frecuentes en la infancia. Excepcionalmente los pacientes con este tipo de epilepsias tienen evoluciones atípicas que constituyen un reto diagnóstico y terapéutico. Objetivo: Ilustrar la evolución atípica de la epilepsia focal idiopática tipo Panayiotopoulos. Presentación del caso: Adolescente de 13 años que presentó su primera crisis epiléptica a los 5 años de edad, de breve duración, mientras dormía tuvo apertura ocular, desviación de los ojos a la izquierda, abundante salivación y presentó un vómito. En tres años tuvo solo tres crisis. No recibió tratamiento con fármacos antiepilépticos hasta después de la tercera crisis, que fue más prolongada. Tras iniciar tratamiento con carbamazepina comenzó a presentar dificultades en el aprendizaje y marcada hiperactividad. Un electroencefalograma interictal de sueño demostró descargas de punta-ondas continuas en el sueño lento. Después de dos años de tratamiento se alcanzó la normalidad en el estudio electroencefalográfico de sueño, con retirada inicial de la carbamazepina, e introducción progresiva de clobazam y valproato de magnesio. Evolutivamente el paciente mantuvo las dificultades en el aprendizaje, con mejoría notable de su hiperactividad, sin recurrencia de crisis epilépticas. Conclusiones: El caso presentado constituye un ejemplo infrecuente de un paciente con una epilepsia focal idiopática con evolución atípica, probablemente inducida por la carbamazepina, con cuadro clínico-electroencefalográfico de más de dos años de duración, con mejoría favorecida por el tratamiento finalmente empleado, la evolución natural del síndrome o el efecto de ambos (AU)

Introduction: Idiopathic focal epilepsies are one of the most frequent epilepsy groups in childhood. Exceptionally, patients with this type of epilepsy have atypical evolutions that constitute a diagnostic and therapeutic challenge. Objective: To illustrate the atypical evolution of idiopathic focal epilepsy, type Panayiotopoulos. Case presentation: A 13-year-old adolescent who presented his first epileptic seizure at 5 years old, of short duration, while he slept had an eye opening, deviation of the eyes to the left, abundant salivation and vomiting. In three years he had only three seizures. He did not receive treatment with antiepileptic drugs until after the third seizure, which was longer. After starting treatment with carbamazepine, he began to have learning difficulties and marked hyperactivity. A sleep's interictal electroencephalogram showed continuous spikes and wave's discharges during the slow sleep. After two years of treatment, the normalization of the sleep electroencephalogram was achieved, with withdrawal of carbamazepine, and progressive introduction of clobazam and magnesium valproate. The patient remained evolutionarily with learning difficulties, with significant improvement in hyperactivity, without recurrence of seizures. Conclusions: The case presented is an infrequent example of a patient with idiopathic focal epilepsy with atypical evolution, probably induced by carbamazepine, with clinical-electroencephalographic symptoms during more than two years, with improvement favored by the final treatment used, the natural evolution of the syndrome or the effect of both(AU)

Encephalopathy with continuous spike-waves during slow-wave sleep: evolution and prognosis.

Encephalopathy with continuous spike-waves during slow-wave sleep (CSWS) evolves over time, and three stages can be recognized: before the onset of CSWS, during CSWS, and after the CSWS period. Clinical seizures tend to remit spontaneously around puberty. This pattern is independent of the etiological lesion. The CSWS also disappears in all cases. Focal abnormalities instead, may persist for some time after the disappearance of CSWS. The disappearance of the clinical seizures and CSWS may be simultaneous or seizures may disappear before or after disappearance of the CSWS pattern on the EEG. Electroclinical parameters in the pre-CSWS period that have been proposed to predict a poor outcome are early-onset seizures, appearance of new seizures, and a significant increase in seizure frequency. From the electrical point of view, an increase in the frequency of the interictal EEG paroxysms while awake and during sleep and bilateral spike-and-wave paroxysms may also be predictive of a poor evolution in CSWS. When CSWS disappears, neurocognitive and behavioral status improve, but in most patients, residual moderate to severe neurocognitive impairments remain. In non-lesional epilepsy, cognitive recovery after cessation of the CSWS depends on the severity and duration of the initial regression. The duration of the CSWS seems to be the most important predictor of cognitive outcome. Early recognition and effective therapy to reduce the seizures and resolve the CSWS may be crucial to improve long-term prognosis. Cognitive recovery is observed in patients who respond well to AED treatment and outcome depends on the etiology.

Hippocampal and cortical communication around micro-arousals in slow-wave sleep.

Sleep plays a crucial role in the regulation of body homeostasis and rhythmicity in mammals. Recently, a specific component of the sleep structure has been proposed as part of its homeostatic mechanism, named micro-arousal. Here, we studied the unique progression of the dynamic behavior of cortical and hippocampal local field potentials (LFPs) during slow-wave sleep-related to motor-bursts (micro-arousals) in mice. Our main results comprised: (i) an abrupt drop in hippocampal LFP amplitude preceding micro-arousals which persisted until the end of motor-bursts (we defined as t interval, around 4s) and a similar, but delayed amplitude reduction in cortical (S1/M1) LFP activity occurring at micro-arousal onset; (ii) two abrupt frequency jumps in hippocampal LFP activity: from Theta (6-12 Hz) to Delta (2-4 Hz), also t seconds before the micro-arousal onset, and followed by another frequency jump from Delta to Theta range (5-7 Hz), now occurring at micro-arousal onset; (iii) a pattern of cortico-hippocampal frequency communication precedes micro-arousals: the analysis between hippocampal and cortical LFP fluctuations reveal high coherence during τ interval in a broader frequency band (2-12 Hz), while at a lower frequency band (0.5-2 Hz) the coherence reaches its maximum after the onset of micro-arousals. In conclusion, these novel findings indicate that oscillatory dynamics pattern of cortical and hippocampal LFPs preceding micro-arousals could be part of the regulatory processes in sleep architecture.