Memory-related hippocampal activation during sleep and temporal memory in toddlers.

Nonhuman research has implicated developmental processes within the hippocampus in the emergence and early development of episodic memory, but research in humans has been constrained by the difficulty of examining hippocampal function during early development. In the present study, we assessed 48 2-year-olds with a novel paradigm in which participants completed two games on a tablet that required remembering associations between unique characters, the places they visited, and the temporal order with which they did so. At the completion of each game, a unique, novel song played. Toddlers remembered spatial locations better than temporal order during an immediate test, after a 20-minute delay, and after a week delay. After the last behavioral session, toddlers underwent an fMRI task during natural nocturnal sleep evaluating hippocampal activation in response to learned and novel songs. We found that the extent of hippocampal activation for learned songs compared to novel songs during sleep was correlated with memory for temproal order across all time delays, but not with memory for spatial locations. The results confirm that that the functional contribution of the hippocampus to early memory can be assessed during sleep and suggest that assessment of temporal aspects of memory in the current task best capture this contribution.

Children with ASD Show Impaired Item-Space Recollection, But Preserved Item-Color Recollection.

Although individuals with autism spectrum disorder (ASD) have been often shown to display similar memory performance on semantic memory tasks compared to typically developing (TD) children, there is ongoing debate about whether and how their ability to remember specific past events (i.e., episodic memory) is impaired. We assessed a sample of 62 children with ASD and 72 TD children, ranging in age between 8 and 12 years on 2 memory tasks. Participants encoded a series of images and their association with either where they appeared on the screen (item-space association task) or with the color of an image's border (item-color association task). Children with ASD showed worse memory in the item-space association task compared to their TD peers, but comparable memory for the item-color association task. These differences persisted when age, intellectual quotient, and general item recognition memory were accounted for statistically. We interpret these results in light of evidence for specific deficits along the dorsal stream affecting processing of spatiotemporal information in ASD. Autism Res 2020, 13: 1985-1997. © 2020 International Society for Autism Research and Wiley Periodicals LLC LAY SUMMARY: Episodic memory requires the ability to bind contextual details (such as color, location, etc.) to an item or event in order to remember the past with specific detail. Here, we compared children with autism spectrum disorder (ASD) and typically developing (TD) children on tasks examining episodic memory. Children with ASD recalled more poorly previously seen items and their associated space-related details, but they performed comparably to TD children on color details. We discuss the possible mechanisms that contribute to worse spatial processing/recall in ASD.

Neuroimaging the sleeping brain: Insight on memory functioning in infants and toddlers.

Episodic memory, or the ability to remember past events with specific detail, is central to the human experience and is related to learning and adaptive functioning in a variety of domains. In typically developing children, episodic memory emerges during infancy and improves during early childhood and beyond. Developmental processes within the hippocampus are hypothesized to be primarily responsible for both the early emergence and persistence of episodic memory in late infancy and early childhood. However, these hypotheses are based on non-human models. In-vivo investigations in early human development of hippocampal processes have been significantly limited by methodological challenges in acquiring neuroimaging data, particularly task-related functional neuroimaging data, from infants and toddlers. Recent studies in adults have shown neural activity in the brain regions supporting episodic memory during slow-wave sleep using functional magnetic resonance imaging (fMRI), and fMRI has been increasingly utilized in infancy and early childhood to address other research questions. We review initial evidence and present preliminary data showing the promise of this approach for examining hippocampal contribution to how infants and toddlers remember individual events, and their association with information about the context in which the event occurred. Overall, our review, integrated with the presentation of some preliminary data provides insight on leveraging sleep to gain new perspectives on early memory functioning.

Motor cortex facilitation: a marker of attention deficit hyperactivity disorder co-occurrence in autism spectrum disorder.

The neural correlates distinguishing youth with Autism Spectrum Disorder (ASD-) and ASD with co-occurring Attention Deficit Hyperactivity Disorder (ASD+) are poorly understood despite significant phenotypic and prognostic differences. Paired-pulse transcranial magnetic stimulation (TMS) measures, including intracortical facilitation (ICF), short interval cortical inhibition (SICI), and cortical silent period (CSP) were measured in an age matched cohort of youth with ASD- (n = 20), ASD + (n = 29), and controls (TDC) (n = 24). ASD- and ASD+ groups did not differ by IQ or social functioning; however, ASD+ had significantly higher inattention and hyperactivity ratings. ICF (higher ratio indicates greater facilitation) in ASD+ (Mean 1.0, SD 0.19) was less than ASD- (Mean 1.3, SD 0.36) or TDC (Mean 1.2, SD 0.24) (F2,68 = 6.5, p = 0.003; post-hoc tests, ASD+ vs either TDC or ASD-, p ≤ 0.05). No differences were found between groups for SICI or age corrected active/resting motor threshold (AMT/RMT). Across all ASD youth (ASD- and ASD+), ICF was inversely correlated with worse inattention (Conners-3 Inattention (r = -0.41; p < 0.01) and ADHDRS-IV Inattention percentile (r = -0.422, p < 0.01) scores. ICF remains intact in ASD- but is impaired in ASD+. Lack of ICF is associated with inattention and executive function across ASD. Taken with the present findings, ADHD may have a distinct electrophysiological "signature" in ASD youth. ICF may constitute an emerging biomarker to study the physiology of ADHD in ASD, which may align with disease prognosis or treatment response.

Psychopharmacology of neurobehavioral disorders.

At times psychotropic drug use is required to address behavioral and other interfering symptoms that accompany neurobehavioral disorders. We review such prescribing practice in autism spectrum disorder, fragile X syndrome, and Prader-Willi syndrome.

Eye gaze and pupillary response in Angelman syndrome.

BACKGROUND: Angelman syndrome (AS) is a rare neurological disorder characterized by severe developmental disability, communication impairment, elevated seizure risk, and motor system abnormalities. AIMS: The aims of this study were to determine the feasibility of social scene eye tracking and pupillometry measures in individuals with AS and to compare the performance of AS participants to individuals with idiopathic Autism Spectrum Disorder (ASD) and typically developing controls (TDC). METHODS AND PROCEDURES: Individuals with AS and age- and gender- matched controls completed a social eye tracking paradigm. Neurobehavioral characterization of AS participants was completed via a battery of psychological testing and caregiver behavioral evaluations. OUTCOMES AND RESULTS: Eight of seventeen recruited AS participants completed the eye tracking paradigm. Compared to TDC, AS subjects demonstrated significantly less preference for social scenes than geometric shapes. Additionally, AS subjects showed less pupil dilation, compared to TDC, when viewing social scenes versus geometric shapes. There was no statistically significant difference found between AS and ASD subjects in either social eye tracking or pupillometry. CONCLUSIONS AND IMPLICATIONS: The use of eye tracking and pupillometry may represent an innovative measure for quantifying AS-associated impairments in social salience.