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.
The Adolescent Brain Cognitive Development (ABCD) Study is an ongoing, nationwide study of the effects of environmental influences on behavioral and brain development in adolescents.The ABCD Study is a collaborative effort, including a Coordinating Center, 21 data acquisition sites across the United States, and a Data Analysis and Informatics Center (DAIC). The main objective of the study is to recruit and assess over eleven thousand 9-10-year-olds and follow them over the course of 10 years to characterize normative brain and cognitive development, the many factors that influence brain development, and the effects of those factors on mental health and other outcomes. The study employs state-of-the-art multimodal brain imaging, cognitive and clinical assessments, bioassays, and careful assessment of substance use, environment, psychopathological symptoms, and social functioning. The data will provide a resource of unprecedented scale and depth for studying typical and atypical development. Here, we describe the baseline neuroimaging processing and subject-level analysis methods used by the ABCD DAIC in the centralized processing and extraction of neuroanatomical and functional imaging phenotypes. Neuroimaging processing and analyses include modality-specific corrections for distortions and motion, brain segmentation and cortical surface reconstruction derived from structural magnetic resonance imaging (sMRI), analysis of brain microstructure using diffusion MRI (dMRI), task-related analysis of functional MRI (fMRI), and functional connectivity analysis of resting-state fMRI.
word count: 250 Main text word count: 4302 Number of Figures: 4 Number of Tables: 0 Supplementary Information: 1 figure, 2 tables ABSTRACT 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 EEG was successfully recorded in 18 females with RTT and 27 agematched typically developing (TD) controls (aged 6-22 years). Data from 7 RTT and 3 TD participants were excluded for excessive noise. Stimuli were 1kHz tones with a standard duration of 100ms and deviant duration of 180ms. To assess the sustainability of sensory memory, stimulus presentation rate was varied with stimulus onset asynchronies (SOAs) of 450, 900 and 1800ms. MMNs with maximum negativity over fronto-central scalp and a latency of 220-230ms 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.
Perinatal ischemic stroke is a leading cerebrovascular disorder occurring in infants around the time of birth associated with long term comorbidities including motor, cognitive and behavioral deficits. We sought to determine the impact of perinatal induced stroke on locomotion, behavior and motor function in rats. A photothrombotic model of ischemic stroke was used in rat at postnatal day 7. Presently, we induced two lesions of different extents, to assess the consequences of stroke on motor function, locomotion and possible correlations to morphological changes. Behavioral tests sensitive to sensorimotor changes were used; locomotion expressed as distance moved in the open field was monitored and histological changes were also assessed. Outcomes depicted two kinds of lesions of different shapes and sizes, relative to laser illumination. Motor performance of rats submitted to stroke was poor when compared to controls; a difference in motor performance was also noted between rats with small and large lesions. Correlations were observed between: motor performance and exposition time; volume ratio and exposition time; and in the rotarod between motor performance and volume ratio. Outcomes demonstrate that photothrombotic cerebral ischemic stroke induced in early postnatal period and tested in adulthood, indeed influenced functional performance governed by the affected brain regions.
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