Excitation-inhibition (E:I) imbalance is theorized as an important pathophysiological mechanism in autism. Autism affects males more frequently than females and sex-related mechanisms (e.g., X-linked genes, androgen hormones) can influence E:I balance. This suggests that E:I imbalance may affect autism differently in males versus females. With a combination of in-silico modeling and in-vivo chemogenetic manipulations in mice, we first show that a time-series metric estimated from fMRI BOLD signal, the Hurst exponent (H), can be an index for underlying change in the synaptic E:I ratio. In autism we find that H is reduced, indicating increased excitation, in the medial prefrontal cortex (MPFC) of autistic males but not females. Increasingly intact MPFC H is also associated with heightened ability to behaviorally camouflage social-communicative difficulties, but only in autistic females. This work suggests that H in BOLD can index synaptic E:I ratio and that E:I imbalance affects autistic males and females differently.

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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.

Auditory processing is an important component of cognitive development, and names are among the most frequently occurring receptive language stimuli. Although own name processing has been examined in infants and adults, surprisingly little data exist on responses to own name in children. The present ERP study examined spoken name processing in 32 children (M=7.85 years) using a passive listening paradigm. Our results demonstrated that children differentiate own and close other’s names from unknown names, as reflected by the enhanced parietal P300 response. The responses to own and close other names did not differ between each other. Repeated presentations of an unknown name did not result in the same familiarity as the known names. These results suggest that auditory ERPs to known/unknown names are a feasible means to evaluate complex auditory processing without the need for overt behavioral responses.

BackgroundPeople with Prader-Willi syndrome (PWS) demonstrate social dysfunction and increased risk of autism spectrum disorder, especially those with the maternal uniparental disomy (mUPD) versus paternal deletion genetic subtype. This study compared the neural processing of social (faces) and nonsocial stimuli, varying in emotional valence, across genetic subtypes in 24 adolescents and adults with PWS.MethodsUpright and inverted faces, and nonsocial objects with positive and negative emotional valence were presented to participants with PWS in an oddball paradigm with smiling faces serving as targets. Behavioral and event-related potential (ERP) data were recorded.ResultsThere were no genetic subtype group differences in accuracy, and all participants performed above chance level. ERP responses revealed genetic subtype differences in face versus object processing. In those with deletions, the face-specific posterior N170 response varied in size for face stimuli versus inverted faces versus nonsocial objects. Persons with mUPD generated N170 of smaller amplitude and showed no stimulus differentiation. Brain responses to emotional content did not vary by subtype. All participants elicited larger posterior and anterior late positive potential responses to positive objects than to negative objects. Emotion-related differences in response to faces were limited to inverted faces only in the form of larger anterior late positive potential amplitudes to negative emotions over the right hemisphere. Detection of the target smiling faces was evident in the increased amplitude of the frontal and central P3 responses but only for inverted smiling faces.ConclusionPersons with the mUPD subtype of PWS may show atypical face versus object processes, yet both subtypes demonstrated potentially altered processing, attention to and/or recognition of faces and their expressions.

This study was performed to measure changes in cerebral blood volume (CBV) associated with visual activation by use of bolus administration of contrast agent and conventional, clinically configured magnetic resonance (MR) hardware and software. Fast gradient-recalled acquisition in the steady state technique was used to study five healthy subjects during visual activation and a control dark state. MR images were obtained every 2.048 seconds for 2 minutes. A bolus of gadopentetate dimeglumine was injected during visual stimulation and darkness. Cine images produced from the series of rapid images clearly depicted arterial, capillary, and venous phases. Analysis of serial concentration maps derived from the rapid images revealed expected differences between the relative CBV of gray matter and that of white matter, as well as significantly increased relative CBV in calcarine cortex during visual activation versus the control state (mean increase, 15.24%; range, 6.41%-27.78%; P < .05). These results confirm those reported in echo-planar imaging studies and demonstrate that brain function can be assessed with the bolus method by means of MR imaging hardware and software with conventional clinical configurations.

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The combination of intellectual, communicative, and motor deficits limit the use of standardized behavioral assessments of cognition in individuals with Angelman syndrome (AS). The current study is the first to objectively evaluate learning and memory in AS using auditory event-related potentials (ERP) during passive exposure to spoken stimuli. Fifteen nonverbal individuals with the deletion subtype of AS (age 4–45 years) completed the auditory incidental memory paradigm. Auditory ERPs were recorded in response to a sequence of unfamiliar nonwords, in which one randomly selected stimulus was repeated multiple times and the rest were presented once. Larger parietal responses within 200–500ms for the repeated nonword compared to novel distracters were associated with caregiver reports of more adaptive communication skills. These findings demonstrate good tolerability of ERP procedures (94% success rate) and indicate that persons with AS can acquire new information following repeated auditory exposure, even in the absence of explicit memorization instructions. Strong associations between the caregiver reports of adaptive functioning and neural indices of auditory learning and memory support the utility of brain-based measures for objectively evaluating higher-order information processing in nonverbal persons with neurodevelopmental disorders.