Aspects of Attention in Rett Syndrome

Insights into Rett Syndrome girls' receptive vocabulary through eye movements and parental perception

OBJECTIVE

This study evaluated the receptive vocabulary of girls diagnosed with Rett Syndrome (RS) by employing eye-tracking technology and examined how these objective measures compared with parents' perceptions of their daughters' language abilities.

METHOD

Fourteen girls with RS and eleven typically developing peers participated. Instruments included the Kerr Scale, a parental questionnaire on communication skills, the Peabody Picture Vocabulary Test - PPVT-4, and eye-tracking equipment. The PPVT-4's initial 12 cards, each displaying four images, were presented on screen for 5 s for the child's initial inspection. Subsequently, the same card was shown for 5 s with instructions to identify the picture matching the word, repeated three times in a randomized order.

RESULTS

Eye-tracking assessments revealed that girls with RS with less severe symptoms, performed below typically developing peers with aged 3-4 years. The number of eye fixations emerged as a reliable metric for assessing their performance. A positive correlation was found between parental reports of their daughters' vocabulary knowledge and their ability to identify the correct stimulus, suggesting comprehension and active engagement in the testing process.

CONCLUSION

This study presents a pioneering approach by combining parental perceptions with eye-tracking measures to assess receptive vocabulary in girls diagnosed with Rett Syndrome. Despite showing lower performance levels compared to significantly younger peers, the findings suggest that these individuals use less effectively eye contact as a mode of communication.

Sleep and the Social Profiles of Individuals With Rett Syndrome

BACKGROUND

This study investigates the distinctive social behaviors observed in individuals with Rett syndrome (RTT), characterized by the loss of spoken language, impaired eye gaze communication, gait abnormalities, and sleep issues. The research aims to identify social profiles in RTT and explore their correlation with sleep, sleep-disordered breathing (SDB), and daytime sleepiness.

METHODS

Standard overnight sleep macrostructure and respiratory parameters were assessed. Extracting 25 social-related items and one for daytime sleepiness from the Rett Syndrome Behavioral Questionnaire, factor analysis was applied to establish latent social profiles. These profiles were then correlated with sleep parameters. The nonparametric Mann-Whitney U test compared social profiles based on the presence of SDB (defined by an apnea-hypopnea index greater than one per hour) and daytime sleepiness.

RESULTS

The study involved 12 female subjects with confirmed RTT diagnoses and MECP2 mutations, aged 8.54 ± 5.30 years. The Rett Syndrome Behavioral Questionnaire revealed a total average score of 25.83 ± 12.34, indicating varying degrees of social impairments. Comprising 25 social-related items, factor analysis yielded four social profiles: "interactive motricity," "mood change," "anxiety/agitation," and "gazing." Longer sleep onset latency correlated with increased socio-behavioral impairments, particularly in interactive motricity reduction. Conversely, higher rapid eye movement sleep was associated with fewer interactive socio-motor behaviors. No significant differences in social profiles were found concerning the presence of SDB or daytime sleepiness.

CONCLUSIONS

The findings suggest four distinct social profiles in RTT individuals, hinting at shared disrupted circuits between sensorimotor functioning and sleep-related neuronal pathways. Despite the absence of differences in SDB or daytime sleepiness, the study highlights the relationship between sleep parameters, such as sleep onset latency and rapid eye movement sleep, and socio-behavioral outcomes in RTT with MECP2 mutations.

Aided language modelling, responsive communication and eye-gaze technology as communication intervention for adults with Rett syndrome: three experimental single case studies

PURPOSE

To examine the effect of a communication intervention package on expressive communication and visual attention in individuals with Rett syndrome.

MATERIALS AND METHODS

A modified withdrawal (A-B1-A1-B2-A2) single case experimental design with a direct inter-subject replication across three participants was applied. Three women with Rett syndrome participated. The study took place over a six-week period and comprised 32 sessions with each participant. All sessions were video recorded. During the intervention the communication partner used aided language modelling on a gaze-controlled device in combination with using responsive partner strategies. Expressive communication was assessed as synthesised words per minute and unique synthesised words per minute. Visual attention was assessed as rate of focused gazes (1 s or longer) in interaction.

RESULTS

An intervention effect was found on the rate of unique words for all participants. The rate of words increased for two participants when the intervention was introduced but no withdrawal effect could be seen. An intervention effect on visual attention could be seen for one participant. The intervention appeared to have social validity as reported by caregivers.

CONCLUSION

Aided language modelling (ALM), while using responsive partner strategies and a gaze-controlled device may be used with adult individuals with Rett syndrome to increase their rate of expressive communication. Detailed observational measures revealed individual learning patterns, which may provide clinically valuable insights.Implications for RehabilitationAdults with Rett syndrome may benefit from access to gaze-controlled devices in combination with responsive partner strategies.Responsive partner communication may be effective for some individuals with Rett syndrome to increase their rate of synthesised utterances.Rate of focused gazes may be considered as an outcome measure for individuals with oculomotor difficulties when introducing aided language modelling.

Documentación de habilidades comunicativas y de lenguaje receptivo en un caso de Síndrome de Rett

Las dificultades de las personas con síndrome de Rett (SR) para hablar y producir respuestas motoras hace de la valoración un proceso difícil, resultando necesario combinar métodos informales y adaptaciones en los instrumentos formales para obtener información sobre los niveles de competencia. El objetivo de este estudio es documentar el proceso de valoración de las habilidades comunicativo-lingüísticas seguido con una niña con SR combinando métodos de evaluación y realizando adaptaciones en los tests estandarizados. Se llevaron a cabo observaciones informales en entornos naturales, los compañeros de comunicación cubrieron la Matriz de Comunicación, y se realizaron adaptaciones en los tests Vocabulario en Imágenes Peabody y TSA de desarrollo de la morfosintaxis, y en el Test of Aided Communication Performance, consistentes en reducir el número de alternativas, presentarlas en una disposición accesible a la señalización con la mirada, y en dar tiempo de espera para la respuesta de la participante con SR. Los resultados obtenidos mediante las adaptaciones utilizando la mirada como método de acceso mostraron niveles de dominio de comunicación preintencional y de comunicación no convencional, junto con destrezas emergentes en comunicación convencional y simbólica para funciones de petición e interacción social y una comprensión de estructuras gramaticales sencillas. La conclusión que se desprende es que es imperativo que las evaluaciones se adapten a las limitaciones físicas y orales de las personas con SR, de modo que puedan descubrirse capacidades ocultas, se establezcan objetivos para la intervención basados en sus niveles reales de competencia para apoyar al máximo la comunicación.

Cognitive stimulation has potential for brain activation in individuals with Rett syndrome

BACKGROUND

Knowledge regarding neuropsychological training in Rett syndrome (RS) is scarce. The aim of this study was to assess the outcome and the duration of the effect of cognitive stimulation on topographic electroencephalography (EEG) data in RS.

METHODS

Twenty female children diagnosed with RS were included in the analysis. Girls with RS conducted a cognitive task using an eye-tracker designed to evaluate access and choice skills. EEG data were acquired during the experimental procedure including two 10-min baseline stages before and after the task. Topographical changes of several EEG spectral markers including absolute and relative powers, Brain Symmetry Index and entropy were assessed.

RESULTS

Topographic significance probability maps suggested statistical decreases on delta activity and increases on beta rhythm associated with the cognitive task. Entropy increased during and after the task, likely related to more complex brain activity. A significant positive interaction was obtained between Brain Symmetry Index and age showing that the improvement of interhemispheric symmetry was higher in younger girls (5-10 years).

CONCLUSIONS

According to our findings, significant alterations of brain rhythms were observed during and after cognitive stimulation, suggesting that cognitive stimulation may have effects on brain activity beyond the stimulation period. Finally, our promising results also showed an increase brain symmetry that was especially relevant for the younger group. This could suggest an interaction of the eye-tracking cognitive task; however, further studies in this field are needed to assess the relation between brain asymmetries and age.

A comparison of formal and informal methods for assessing language and cognition in children with Rett syndrome

BACKGROUND

Opinions about the cognitive and receptive language skills of people with Rett syndrome (RTT) range from severe intellectual impairment to near-normal development. Assessment is challenging because most are non-verbal, with no purposeful hand use. Clarkson et al. (2017) adapted the Mullen Scales of Early Learning for use with eye gaze technology (MSEL-A/ET) for people with RTT.

AIMS

To investigate and compare the performance of children with RTT on formal and newly-designed informal assessments of language and cognition using eye gaze/tracking technology.

METHODS AND PROCEDURES

Ten children with RTT aged 4:0-6:8 were assessed on the MSEL-A/ET for Visual Reception (VR) and Receptive Language (RL), and standard MSEL for Expressive Language (EL). Informal assessments of the same skills were embedded in activities such as reading and cake-decorating.

OUTCOMES AND RESULTS

Standard scores on MSEL-A/ET VR and RL subtests ranged from 'very low' to 'above average'. All children scored 'very low' on standard EL assessment. Informal assessments added information about EL, with children producing 1-3 word utterances and a range of communicative functions through an eye gaze device.

CONCLUSIONS AND IMPLICATIONS

Combining low-tech augmentative and alternative communication, eye gaze technology, informal activities and formal assessment, yields greater insight into children's abilities. This is important in informing suitable support and education for the individual.

Social and Cognitive Interactions Through an Interactive School Service for RTT Patients at the COVID-19 Time

Background: The closure of all educational institutions and most rehabilitation centres represents a precautionary measure to face the COVID-19 pandemic, but the isolation and social distancing may be particularly challenging for children with special needs and disabilities (SEND), such as Rett Syndrome (RTT). The main aim of this study was to promote cognitive and social interactions among children with RTT through an interactive school program. Methods: The Interactive School palimpsest was composed of moments in which a teacher spoke directly to children with RTT and expected a response through eye gaze, and moments in which storeys-cartoon were presented while tracking the eye gaze of children. We investigated behavioural, social and cognitive parameters. Results: Children participated in both social and cognitive tasks with the spontaneous reduction of stereotypies and with increase in attention. They recalled more significant indexes when music or a song was presented together with a cartoon or a cognitive task. Conclusions: This study provides initial insights in promoting cognitive and social interactions and in the support needs of families with a child with RTT during the COVID-19 pandemic.

Social and Cognitive Interactions Through an Interactive School Service for RTT Patients at the COVID-19 Time

Background: The closure of all educational institutions and most rehabilitation centres represents a precautionary measure to face the COVID-19 pandemic, but the isolation and social distancing may be particularly challenging for children with special needs and disabilities (SEND), such as Rett Syndrome (RTT). The main aim of this study was to promote cognitive and social interactions among children with RTT through an interactive school program. Methods: The Interactive School palimpsest was composed of moments in which a teacher spoke directly to children with RTT and expected a response through eye gaze, and moments in which storeys-cartoon were presented while tracking the eye gaze of children. We investigated behavioural, social and cognitive parameters. Results: Children participated in both social and cognitive tasks with the spontaneous reduction of stereotypies and with increase in attention. They recalled more significant indexes when music or a song was presented together with a cartoon or a cognitive task. Conclusions: This study provides initial insights in promoting cognitive and social interactions and in the support needs of families with a child with RTT during the COVID-19 pandemic.

Frontal Cortical Monoamine Release, Attention, and Working Memory in a Perinatal Nicotine Exposure Mouse Model Following Kappa Opioid Receptor Antagonism

Perinatal nicotine exposure (PNE) produces frontal cortical hypo-dopaminergic state and attention and working memory deficits consistent with neurodevelopmental disorders such as attention deficit hyperactivity disorder (ADHD). Methylphenidate alleviates ADHD symptoms by increasing extracellular dopamine and noradrenaline. Kappa opioid receptor (KOR) antagonism may be another mechanism to achieve the same results because KOR activation inhibits frontal cortical dopamine release. We administered the selective KOR antagonist norbinaltorphimine (norBNI) (20 mg/kg; intraperitoneal) or methylphenidate (0.75 mg/kg; intraperitoneal) to PNE mouse model and examined frontal cortical monoamine release, attention, and working memory. Both compounds increased dopamine and noradrenaline release but neither influenced serotonin release. Both compounds improved object-based attention and working memory in the PNE group, with norBNI's effects evident at 2.5 h and 5.5 h but absent at 24 h. Methylphenidate's effects were evident at 0.5 h but not at 2.5 h. norBNI's effects temporally coincided with frontal cortical c-Jun N-terminal kinase phosphorylation. norBNI did not alter tissue dopamine content in the nucleus accumbens, offering preliminary support for lack of reinforcement.

Development of a tool to assess visual attention in Rett syndrome: a pilot study

This was a two-phase study that aimed to (a) develop a tool for assessing visual attention in individuals with Rett syndrome using AAC with a communication partner during naturalistic interactions in clinical settings; and (b) explore aspects of the tool's reliability, validity, and utility. The Assessment of Visual Attention in Interaction (AVAI) tool was developed to assess visual attention operationalized as focused gazes (1 s or longer) at the communication partner, an object, and a symbol set. For the study, six video-recorded interactions with nine female participants diagnosed with Rett syndrome (range: 15-52-years-old) were used to calculate intra- and inter-rater agreement, and 18 recorded interactions were analyzed to examine sensitivity to change and acceptability. There was a significant difference in the AVAI results between two conditions (with and without aided-language modeling). Inter-rater agreement ranged from moderate and strong. There was a range in scores, indicating that the AVAI could differentiate between participants. The AVAI was found to be reliable, able to detect change, and acceptable to the participants. This tool could potentially be used for evaluating interventions that utilize aided AAC.

Increased attention to snake images in cynomolgus monkeys: an eye-tracking study

Previous studies have revealed faster detection of snake images in humans and non-human primates (NHPs), suggesting automatic detection of evolutionary fear-relevant stimuli. Furthermore, human studies have indicated that general fear-relevance rather than evolutionary relevance is more effective at capturing attention. However, the issue remains unclarified in NHPs. Thus, in the present study, we explored the attentional features of laboratory-reared monkeys to evolutionary and general fear-relevant stimuli (e.g., images of snakes, capturing gloves). Eye-tracking technology was utilized to assess attentional features as it can provide more accurate latency and variables of viewing duration and frequency compared with visual search task (VST) and response latency adopted in previous studies. In addition, those with autism spectrum disorder (ASD) show abnormal attention to threatening stimuli, including snake images. Rett syndrome (RTT) is considered a subcategory of ASD due to the display of autistic features. However, the attentional features of RTT patients or animal models to such stimuli remain unclear. Therefore, we also investigated the issue in MECP2 gene-edited RTT monkeys. The influence of different cognitive loads on attention was further explored by presenting one, two, or four images to increase stimulus complexity. The eye-tracking results revealed no significant differences between RTT and control monkeys, who all presented increased viewing (duration and frequency) of snake images but not of aversive stimuli compared with control images, thus suggesting attentional preference for evolutionary rather than general fear-relevant visual stimuli. Moreover, the preference was only revealed in visual tasks composed of two or four images, suggesting its cognitive-load dependency.

Social-valence-related increased attention in rett syndrome cynomolgus monkeys: An eye-tracking study

The cognitive phenotypes of Rett syndrome (RTT) remain unclarified compared with the well-defined genetic etiology. Recent clinical studies suggest the eye-tracking method as a promising avenue to quantify the visual phenotypes of the syndrome. The present study explored various aspects of visual attention of the methyl-CpG-binding protein 2 gene mutant RTT monkeys with the eye-tracking procedure. Comprehensive testing paradigms, including social valence comparison (SVC), visual paired comparison (VPC), and social recognition memory (SRM), were utilized to investigate their attentional features to social stimuli with differential valence, the novelty preferences, and short-term recognition memory, respectively. To explore the neurobiological mechanisms underlying the eye-tracking findings, we assessed changes of the brain subregion volumes and neurotransmitter concentrations. Compared with control monkeys, RTT monkeys demonstrated increased viewing on the more salient stare faces than profile faces in the SVC test, and increased viewing on the whole presented images composed of monkey faces in the VPC and SRM tests. Brain imaging revealed reduced bilateral occipital gyrus in RTT monkeys. The exploratory neurotransmitter analyses revealed no significant changes of various neurotransmitter concentrations in the cerebrospinal fluid and blood of RTT monkeys. The eye-tracking results suggested social-valence-related increased attention in RTT monkeys, supplementing the cognitive phenotypes associated with the syndrome. Further investigations from broader perspectives are required to uncover the underlying neurobiological mechanisms. Autism Res 2019, 00: 1-13. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Altered expressions of the methyl-CpG-binding protein 2 (MECP2) gene are usually associated with neurodevelopmental disorders, such as autism spectrum disorders, Rett syndrome (RTT), and so forth. The present eye-tracking study found social-valence-related increased attention in our firstly established MECP2 mutant RTT monkeys. The novel findings supplement the cognitive phenotypes and potentially benefit the behavioral interventions of the RTT syndrome.

Challenges in evaluating the oculomotor function in individuals with Rett syndrome using electronystagmography

BACKGROUND

Rett syndrome (RTT) is a neurological disorder characterized by a broad spectrum of symptoms. Communication is a major area of difficulty. Use of eye tracking technology offers a potentially effective method of communication when underpinned by intact oculomotor function. In this study, oculomotor function was assessed using electronystagmography (ENG). However, challenges were encountered when examining individuals with RTT.

PURPOSE

To improve oculomotor examination in individuals with RTT by evaluating the challenges encountered during ENG examination.

MATERIAL AND METHODS

Oculomotor function was examined in 17 girls and young women with RTT and 16 typically developing (TD) individuals using ENG. Observational analysis of both performance and results indicated that challenges in examination were mainly related to quality of attention and quality of signals. Subsequently these outcome values were explored quantitatively according to percentage looking time for attention and drift for signal quality.

RESULTS

A significantly reduced level of attention and suboptimal electrode signals were evident in the RTT group when compared with the TD group for all tests except torsion swing.

CONCLUSION

The challenges in testing confirm that regular oculomotor examination should be adjusted to meet the needs of individuals with RTT. It is hypothesized that the RTT group's higher quality of attention on the torsion swing can be explained by the more forceful vestibular rather than visual-ocular stimulus operating in this test. Suggested adaptations include reducing the number of electrodes, changing the picture stimuli and bringing them closer, performing observational assessments rather than ENG, and using virtual reality goggles.

Impaired Visual Search in Children with Rett Syndrome

AIM

This study aims to investigate selective attention in Rett syndrome, a severely disabling neurodevelopmental disorder caused by mutations in the X-linked MECP2 gene.

METHOD

The sample included 28 females with Rett syndrome (RTT) and 32 age-matched typically developing controls. We used a classic search task, in conjunction with eye-tracking technology. Each trial included the target and several distractors. The distractors varied in number and differed from targets in either a "single feature" (color or shape), creating a pop-out effect, or in a "conjunction of features" (color and shape), requiring serial search. Children searched for the target in arrays containing five or nine objects; trials ended when the target was fixated (or 4000 ms elapsed).

RESULTS

Children with Rett syndrome had more difficulty finding the target than typically developing children in both conditions (success rates less than 50% versus 80%) and their success rates were little influenced by display size or age. Even when successful, children with RTT took significantly longer to respond (392 to 574 ms longer), although saccadic latency differences were observed only in the single-feature condition. Both groups showed the expected slowing of saccadic reaction times for larger arrays in the conjunction-feature condition. Search failures in RTT were not related to symptom severity.

CONCLUSIONS

Our findings provide the first evidence that selective attention, the ability to focus on or select a particular element or object in the environment, is compromised by Rett syndrome. They reinforce the notion that gaze-based tasks hold promise for quantifying the cognitive phenotype of RTT.

Oculomotor Function in Individuals With Rett Syndrome

BACKGROUND

Individuals with Rett syndrome (RTT) are notoriously reliant on the use of eye gaze as a primary means of communication. Underlying an ability to communicate successfully via eye gaze is a complex matrix of requirements, with an intact oculomotor system being just one element. To date, the underlying neural and motor pathways associated with eye gaze are relatively under-researched in RTT.

PURPOSE

This study was undertaken to plug this gap in knowledge and to further the understanding of RTT in one specific area of development and function, namely oculomotor function.

MATERIAL AND METHODS

The eye movements of 18 girls and young women with RTT were assessed by electronystagmography (ENG). This tested their horizontal saccadic and smooth pursuit eye movements as well as optokinetic nystagmus and vestibulo-ocular reflex. Their results were compared with normative data collected from 16 typically developing children and teenagers.

RESULTS

Overall, the individuals with RTT demonstrated a range of eye movements on a par with their typically developing peers. However, there were a number of difficulties in executing the ENG testing with the RTT cohort which made quantitative analysis tricky, such as reduced motivation and attention to test materials and low-quality electrode signals.

CONCLUSIONS

This study suggests that individuals with RTT have an intact oculomotor system. However, modifications should be made to the ENG assessment procedure to combat problems in testing and add strength to the results. Further investigation into these testing difficulties is warranted in order to inform such modifications.

Imaging genetics in neurodevelopmental psychopathology

Neurodevelopmental disorders are defined by highly heritable problems during development and brain growth. Attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), and intellectual disability (ID) are frequent neurodevelopmental disorders, with common comorbidity among them. Imaging genetics studies on the role of disease-linked genetic variants on brain structure and function have been performed to unravel the etiology of these disorders. Here, we reviewed imaging genetics literature on these disorders attempting to understand the mechanisms of individual disorders and their clinical overlap. For ADHD and ASD, we selected replicated candidate genes implicated through common genetic variants. For ID, which is mainly caused by rare variants, we included genes for relatively frequent forms of ID occurring comorbid with ADHD or ASD. We reviewed case-control studies and studies of risk variants in healthy individuals. Imaging genetics studies for ADHD were retrieved for SLC6A3/DAT1, DRD2, DRD4, NOS1, and SLC6A4/5HTT. For ASD, studies on CNTNAP2, MET, OXTR, and SLC6A4/5HTT were found. For ID, we reviewed the genes FMR1, TSC1 and TSC2, NF1, and MECP2. Alterations in brain volume, activity, and connectivity were observed. Several findings were consistent across studies, implicating, for example, SLC6A4/5HTT in brain activation and functional connectivity related to emotion regulation. However, many studies had small sample sizes, and hypothesis-based, brain region-specific studies were common. Results from available studies confirm that imaging genetics can provide insight into the link between genes, disease-related behavior, and the brain. However, the field is still in its early stages, and conclusions about shared mechanisms cannot yet be drawn.