Identification of neural oscillations and epileptiform changes in human brain organoids.

Brain organoids represent a powerful tool for studying human neurological diseases, particularly those that affect brain growth and structure. However, many diseases manifest with clear evidence of physiological and network abnormality in the absence of anatomical changes, raising the question of whether organoids possess sufficient neural network complexity to model these conditions. Here, we explore the network-level functions of brain organoids using calcium sensor imaging and extracellular recording approaches that together reveal the existence of complex network dynamics reminiscent of intact brain preparations. We demonstrate highly abnormal and epileptiform-like activity in organoids derived from induced pluripotent stem cells from individuals with Rett syndrome, accompanied by transcriptomic differences revealed by single-cell analyses. We also rescue key physiological activities with an unconventional neuroregulatory drug, pifithrin-α. Together, these findings provide an essential foundation for the utilization of brain organoids to study intact and disordered human brain network formation and illustrate their utility in therapeutic discovery.

Auditory sensory memory span for duration is severely curtailed in females with Rett syndrome.

Rett syndrome (RTT), a rare neurodevelopmental disorder caused by mutations in the MECP2 gene, is typified by profound cognitive impairment and severe language impairment, rendering it very difficult to accurately measure auditory processing capabilities behaviorally in this population. Here we leverage the mismatch negativity (MMN) component of the event-related potential to measure the ability of RTT patients to decode and store occasional duration deviations in a stream of auditory stimuli. Sensory memory for duration, crucial for speech comprehension, has not been studied in RTT.High-density electroencephalography was successfully recorded in 18 females with RTT and 27 age-matched typically developing (TD) controls (aged 6-22 years). Data from seven RTT and three TD participants were excluded for excessive noise. Stimuli were 1 kHz tones with a standard duration of 100 ms and deviant duration of 180 ms. To assess the sustainability of sensory memory, stimulus presentation rate was varied with stimulus onset asynchronies (SOAs) of 450, 900, and 1800 ms. MMNs with maximum negativity over fronto-central scalp and a latency of 220-230 ms were clearly evident for each presentation rate in the TD group, but only for the shortest SOA in the RTT group. Repeated-measures ANOVA revealed a significant group by SOA interaction. MMN amplitude correlated with age in the TD group only. MMN amplitude was not correlated with the Rett Syndrome Severity Scale. This study indicates that while RTT patients can decode deviations in auditory duration, the span of this sensory memory system is severely foreshortened, with likely implications for speech decoding abilities.

A Coordinated Attack: Rett Syndrome Therapeutic Development.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the Methyl CpG binding protein 2 (MeCP2) gene. This Science & Society article focuses on pharmacological strategies that attack RTT treatment from multiple angles, including drug repurposing and de novo discovery efforts, and discusses the impacts of preclinical study design and translationally relevant outcome measures.

Spoken word processing in Rett syndrome: Evidence from event-related potentials.

This study examined the feasibility of using auditory event-related potentials to evaluate spoken word processing during passive listening in girls with Rett syndrome (n = 11) and typical peers (n = 33), age 4-12 years. The typical group demonstrated the expected pattern of more negative amplitudes within 200-500 ms in response to words than nonwords at left temporal sites. In participants with Rett syndrome, word-nonword differentiation was observed at the right temporal sites. More negative left hemisphere amplitudes in response to words were associated (at trend level) with better receptive language skills and more adaptive behavior. The results indicate that girls with Rett syndrome differentiate known words from novel nonwords, but may do so using potentially atypical neural processes. Brain-behavior correlations support validity of the proposed neural markers of word processing, making passive listening paradigms a promising approach for assessing speech and language processing in participants with limited spoken language skills.

Choline Rescues Behavioural Deficits in a Mouse Model of Rett Syndrome by Modulating Neuronal Plasticity.

Rett syndrome (RTT) is a postnatal neurodevelopmental disorder that primarily affects girls, with 95% of RTT cases resulting from mutations in the methyl-CpG-binding protein 2 (MECP2) gene. Choline, a dietary micronutrient found in most foods, has been shown to be important for brain development and function. However, the exact effects and mechanisms are still unknown. We found that 13 mg/day (1.7 × required daily intake) of postnatal choline treatment to Mecp2-conditional knockout mice rescued not only deficits in motor coordination, but also their anxiety-like behaviour and reduced social preference. Cortical neurons in the brains of Mecp2-conditional knockout mice supplemented with choline showed enhanced neuronal morphology and increased density of dendritic spines. Modelling RTT in vitro by knocking down the expression of the MeCP2 protein with shRNA, we found that choline supplementation to MeCP2-knockdown neurons increased their soma sizes and the complexity of their dendritic arbors. Rescue of the morphological defects could lead to enhanced neurotransmission, as suggested by an observed trend of increased expression of synaptic proteins and restored miniature excitatory postsynaptic current frequency in choline-supplemented MeCP2-knockdown neurons. Through the use of specific inhibitors targeting each of the known physiological pathways of choline, synthesis of phosphatidylcholine from choline was found to be essential in bringing about the changes seen in the choline-supplemented MeCP2-knockdown neurons. Taken together, these data reveal a role of choline in modulating neuronal plasticity, possibly leading to behavioural changes, and hence, a potential for using choline to treat RTT.

Typical vs. atypical: Combining auditory Gestalt perception and acoustic analysis of early vocalisations in Rett syndrome.

BACKGROUND: Early speech-language development of individuals with Rett syndrome (RTT) has been repeatedly characterised by a co-occurrence of apparently typical and atypical vocalisations. AIMS: To describe specific features of this intermittent character of typical versus atypical early RTT-associated vocalisations by combining auditory Gestalt perception and acoustic vocalisation analysis. METHODS AND PROCEDURES: We extracted N = 363 (pre-)linguistic vocalisations from home video recordings of an infant later diagnosed with RTT. In a listening experiment, all vocalisations were assessed for (a)typicality by five experts on early human development. Listeners' auditory concepts of (a)typicality were investigated in context of a comprehensive set of acoustic time-, spectral- and/or energy-related higher-order features extracted from the vocalisations. OUTCOMES AND RESULTS: More than half of the vocalisations were rated as 'atypical' by at least one listener. Atypicality was mainly related to the auditory attribute 'timbre', and to prosodic, spectral, and voice quality features in the acoustic domain. CONCLUSIONS AND IMPLICATIONS: Knowledge gained in our study shall contribute to the generation of an objective model of early vocalisation atypicality. Such a model might be used for increasing caregivers' and healthcare professionals' sensitivity to identify atypical vocalisation patterns, or even for a probabilistic approach to automatically detect RTT based on early vocalisations.

Distinguishing response to names in Rett and MECP2 Duplication syndrome: An ERP study of auditory social information processing.

Despite significant advances at the level of basic research, the characterization of higher-level processes in Rett and MECP2 Duplication syndrome remains understudied. In this pilot study, we assessed social-emotional information processing by testing whether children (ages 4-12years) with Rett (n=9) and MECP2 Duplication syndrome (n=7) distinguished their own spoken name from other names. We hypothesized that own and familiar names would elicit more positive parietal P300 responses than unknown names, and that the groups would have different neural responses to these stimuli. The MECP2 Duplication group partially mirrored the parietal responses to own name observed in typically developing participants, and better name discrimination correlated with more adaptive behaviors. Conversely, participants with RTT did not resemble the typical group, and showed greater responses to close other names at frontal/central regions. These results may reflect the different consequences of too much (MECP2 Duplication) vs. too little (RTT) MeCP2 protein.

Induced gamma oscillations differentiate familiar and novel voices in children with MECP2 duplication and Rett syndromes.

Normal levels of the methyl CpG-binding protein 2 (MeCP2) are critical to neurologic functioning, and slight alterations result in intellectual disability and autistic features. It was hypothesized that children with MECP2 duplication (overexpression of MeCP2) and Rett syndrome (underexpression of MeCP2) would exhibit distinct electroencephalographic (EEG) indices of auditory stimulus discrimination. In this study, gamma-band oscillatory responses to familiar and novel voices were examined and related to social functioning in 17 children (3-11 years old) with MECP2 duplication (n = 12) and Rett syndrome (n = 5). Relative to the stranger's voice, gamma activity in response to the mother's voice was increased in MECP2 duplication but decreased in Rett syndrome. In MECP2 duplication, greater mother versus stranger differences in gamma activity were associated with higher social functioning. For the first time, brain responses in a passive voice discrimination paradigm show that overexpression and underexpression of MeCP2 have differential effects on cortical information processing.

Neurophysiological responses to music and vibroacoustic stimuli in Rett syndrome.

People with Rett syndrome (RTT) have severe communicative difficulties. They have as well an immature brainstem that implies dysfunction of the autonomic nervous system. Music plays an important role in their life, is often used as a motivating tool in a variety of situations and activities, and caregivers are often clear about people with RTTs favourites. The aim of this study was to investigate physiological and emotional responses related to six different musical stimuli in people with RTT. The study included 29 participants with RTT who were referred to the Swedish Rett Center for medical brainstem assessment during the period 2006-2007. 11 children with a typical developmental pattern were used as comparison. A repeated measures design was used, and physiological data were collected from a neurophysiological brainstem assessment. The continuous dependent variables measured were Cardiac Vagal Tone (CVT), Cardiac Sensitivity to Baroreflex (CSB), Mean Arterial Blood Pressure (MAP) and the Coefficient of Variation of Mean Arterial Blood Pressure (MAP-CV). These parameters were used to categorise brainstem responses as parasympathetic (calming) response, sympathetic (activating) response, arousal (alerting) response and unclear response. The results showed that all participants responded to the musical stimuli, but not always in the expected way. It was noticeable that both people with and without RTT responded with an arousal to all musical stimuli to begin with. Even though the initial expressions sometimes changed after some time due to poor control functions of their brainstem, the present results are consistent with the possibility that the RTT participants' normal responses to music are intact. These findings may explain why music is so important for individuals with RTT throughout life.

Vascular dysfunction in a mouse model of Rett syndrome and effects of curcumin treatment.

Mutations in the coding sequence of the X-linked gene MeCP2 (Methyl CpG-binding protein) are present in around 80% of patients with Rett Syndrome, a common cause of intellectual disability in female and to date without any effective pharmacological treatment. A relevant, and so far unexplored feature of RTT patients, is a marked reduction in peripheral circulation. To investigate the relationship between loss of MeCP2 and this clinical aspect, we used the MeCP2 null mouse model B6.129SF1-MeCP2tm1Jae for functional and pharmacological studies. Functional experiments were performed on isolated resistance mesenteric vessels, mounted on a pressurized myograph. Vessels from female MeCP2(+/-) mice show a reduced endothelium-dependent relaxation, due to a reduced Nitric Oxide (NO) availability secondary to an increased Reactive Oxygen Species (ROS) generation. Such functional aspects are associated with an intravascular increase in superoxide anion production, and a decreased vascular eNOS expression. These alterations are reversed by curcumin administration (5% (w/w) dietary curcumin for 21 days), which restores endothelial NO availability, decreases intravascular ROS production and normalizes vascular eNOS gene expression. In conclusion our findings highlight alterations in the vascular/endothelial system in the absence of a correct function of MeCP2, and uncover related cellular/molecular mechanisms that are rescued by an anti-oxidant treatment.

Síndrome de Rett: doble catéter epidural para control del dolor postoperatorio tras cirugía de escoliosis. Revisión de la bibliografía / Rett syndrome: double epidural catheter for the control of postoperative pain after scoliosis surgery. A literature review

El síndrome de Rett es una enfermedad neurológica grave e incapacitante por un defecto estructural en el brazo corto del cromosoma X (Xq28). Afecta a mujeres y consta de múltiples discapacidades neurológicas progresivas que se manifiestan desde edades tempranas causando invalidez y dependencia de por vida. La escoliosis aparece en más del 50% de los pacientes, con necesidad de corrección quirúrgica en casos de graves angulaciones. Es imprescindible una evaluación preanestésica cuidadosa con el fin de identificar los factores de riesgo y así disminuir la morbimortalidad asociada con el procedimiento quirúrgico. Presentamos el caso de una paciente afectada por este síndrome y escoliosis, programada para la realización de una artrodesis vertebral toracolumbar mediante instrumentación con anestesia general, que transcurrió sin incidentes. Evaluamos las connotaciones específicas de este síndrome, sus potenciales complicaciones y su manejo desde un punto de vista anestésico; remarcando el control del dolor postoperatorio conseguido mediante un doble catéter epidural con infusión de anestésicos locales y fentanilo tras la cirugía(AU)

Rett syndrome is a severe and incapacitating neurological disease caused by a structural defect in the short arm of the X chromosome (Xq28). It affects females and consists of multiple and progressive neurological impairments that start from a young age, leading to lifelong disability and dependency. Scoliosis appears in more than 50% of patients and requires surgical correction in cases where the curvature is severe. Pre-anaesthetic assessment is essential in order to identify the risk factors and thus reduce the morbidity and mortality associated with the surgical procedure. We present the case of a patient affected by this syndrome and scoliosis, who was scheduled to have an instrumented thoracolumbar spine arthrodesis with general anaesthesia, which passed without incident. We evaluate the specific details of this syndrome, its potential complications, and its management from an anaesthetic point of view, emphasising the control of postoperative pain using a double epidural catheter with an infusion of local anaesthetics and fentanyl(AU)

How facial expressions in a Rett syndrome population are recognised and interpreted by those around them as conveying emotions.

Rett syndrome (RTT) is a neurodevelopmental disorder, including autonomic nervous system dysfunctions and severe communication impairment with an extremely limited ability to use verbal language. These individuals are therefore dependent on the capacity of caregivers to observe and interpret communicative signals, including emotional expressions. People in general, including therapists tend to focus on changes in facial expressions to interpret a person's emotional state or choices, but with this population it is difficult to know if the interpretations are correct. The aims of this study were to investigate if the Facial Action Coding System (FACS) could be used to identify facial expressions, and differentiate between those that expressed emotions and those that were elicited by abnormal brainstem activation in RTT. The sample comprised 29 participants with RTT and 11 children with a normal developmental pattern, exposed to six different musical stimuli during non-invasive registration of autonomic brainstem functions. The results indicate that FACS makes it possible both to identify facial expressions and to differentiate between those that stem from emotions and those caused by abnormal brainstem activation. This knowledge may be a great help to an uninitiated observer, who otherwise might incorrectly interpret the latter as an expression of emotion.

Acetyl-L-carnitine improves behavior and dendritic morphology in a mouse model of Rett syndrome.

Rett syndrome (RTT) is a devastating neurodevelopmental disorder affecting 1 in 10,000 girls. Approximately 90% of cases are caused by spontaneous mutations in the X-linked gene encoding methyl-CpG-binding protein 2 (MeCP2). Girls with RTT suffer from severe motor, respiratory, cognitive and social abnormalities attributed to early deficits in synaptic connectivity which manifest in the adult as a myriad of physiological and anatomical abnormalities including, but not limited to, dimished dendritic complexity. Supplementation with acetyl-L-carnitine (ALC), an acetyl group donor, ameliorates motor and cognitive deficits in other disease models through a variety of mechanisms including altering patterns of histone acetylation resulting in changes in gene expression, and stimulating biosynthetic pathways such as acetylcholine. We hypothesized ALC treatment during critical periods in cortical development would promote normal synaptic maturation, and continuing treatment would improve behavioral deficits in the Mecp2(1lox) mouse model of RTT. In this study, wildtype and Mecp2(1lox) mutant mice received daily injections of ALC from birth until death (postnatal day 47). General health, motor, respiratory, and cognitive functions were assessed at several time points during symptom progression. ALC improved weight gain, grip strength, activity levels, prevented metabolic abnormalities and modestly improved cognitive function in Mecp2 null mice early in the course of treatment, but did not significantly improve motor or cognitive functions assessed later in life. ALC treatment from birth was associated with an almost complete rescue of hippocampal dendritic morphology abnormalities with no discernable side effects in the mutant mice. Therefore, ALC appears to be a promising therapeutic approach to treating early RTT symptoms and may be useful in combination with other therapies.

Cholinergic hypofunction in MeCP2-308 mice: beneficial neurobehavioural effects of neonatal choline supplementation.

We studied the long-term effects of a postnatal choline supplementation (from birth till weaning) in the truncated MeCP2-308 mouse model of Rett syndrome. Adult male mutant hemizygous (hz) mice showed a reduction of locomotor activity compared to wild type (wt) littermates. Early choline treatment restored wt-like locomotor activity levels in hz mice. Reduced striatal choline acetyl transferase (ChAT) activity and decreased levels of cortical mRNA NGF were found in hz mice. Choline supplementation increased striatal ChAT activity and also enhanced NGF and BDNF expression in cortical and hippocampal regions. As a whole, postnatal choline supplementation attenuates some of the behavioural and neurobiological abnormalities of the Mecp2-308 phenotype.

Postnatal dietary choline supplementation alters behavior in a mouse model of Rett syndrome.

Rett syndrome (RTT), a neurodevelopmental disorder primarily affecting females, is accompanied by behavioral and neuropathological abnormalities and decreases in brain cholinergic markers. Because the cholinergic system is associated with cognitive and motor functions, cholinergic deficits in RTT may underlie some of the behavioral abnormalities. In rodents, increased choline availability during development enhances transmission at cholinergic synapses and improves behavioral performance throughout life. We examined whether choline supplementation of nursing dams would attenuate deficits in Mecp2(1lox) offspring, a mouse model of RTT. Dams were given choline in drinking water, and pups nursed from birth to weaning. Offspring were assessed on development and behavior. In Mecp2(1lox) males, choline supplementation improved motor coordination and locomotor activity, whereas in females it enhanced grip strength. Choline supplementation did not improve response to fear conditioning. Postnatal choline supplementation attenuates some behavioral deficits in Mecp2(1lox) mice and should be explored further as a therapeutic agent in RTT.

Rett syndrome. Guidelines for individual intervention.

Rett syndrome (RS) is a neurological disorder affecting mainly females. RS is considered the second most frequent cause for severe and complex neurological dysfunction in females after Down syndrome. Patients with RS are characterized by an array of neurological and orthopedic difficulties that mandate an intensive therapeutic intervention program for the duration of the individual's life. Many aspects of the client's well-being and functional status depend on the therapeutic intervention she receives and on her compliance to it. This article will briefly review common intervention approaches for individuals with RS and their present day's application. Due to the notion that individual intervention is the foundation on which progress and development of the functional gains rests, the present article will place basic guidelines for individual intervention with clients with RS. The article is mainly based on the clinical experience of the author and others working with individuals with RS.

The development of visual- and auditory processing in Rett syndrome: an ERP study.

Rett syndrome is a neurodevelopmental disorder that occurs almost exclusively in females. It is characterized by a progressive loss of intellectual functioning and motor skills, and the development of stereotypic hand movements, that occur after a period of normal development. Event-related potentials were recorded to a passive auditory- and visual oddball task in 17 females with Rett syndrome aged between 2 and 60 years, and age-matched controls. Overall the participants with Rett syndrome had longer ERP latencies and smaller ERP amplitudes than the Control group suggesting slowed information processing and reduced brain activation. The Rett groups also failed to show typical developmental changes in event-related brain activity and revealed a marked decline in ERP task modulation with increasing age.

Learning ability in children with Rett syndrome.

The purpose of this article is to present results of a research study examining learning ability in individuals with Rett syndrome. The material for this article was drawn from a more extensive doctoral study, designed to investigate intentional communication in this population, through the use of songs in music therapy. Rett syndrome is a neurological disorder resulting from an X-linked mutation, affecting mainly females, and found across racial and ethnic groups worldwide. One of the main areas affecting functioning in individuals with Rett syndrome is a severe impairment of receptive and expressive communication. This creates difficulties when attempting to reveal their potential learning abilities. This population has been observed as very responsive to music hence music therapy intervention has been advocated in promoting and motivating them to communicate and to learn. Seven girls with Rett syndrome, between ages 4 and 10 participated in the study. A single subject, multiple probe design was applied during 30-min trials, three times per week and lasted 8 months. During the trials the participants were asked to choose from a selection of 18 familiar and unfamiliar songs, while their ability to learn was observed and measured. Findings revealed that all seven girls demonstrated an ability to learn and to sustain learning over time. This intervention demonstrated that individuals with Rett syndrome could be promoted and motivated to communicate and learn when therapeutically employed by a trained music therapists.