The locus coeruleus-norepinephrine system as pacemaker of attention - a developmental mechanism of derailed attentional function in autism spectrum disorder

Monitoring norepinephrine release in vivo using next-generation GRABNE sensors

Norepinephrine (NE) is an essential biogenic monoamine neurotransmitter. The first-generation NE sensor makes in vivo, real-time, cell-type-specific and region-specific NE detection possible, but its low NE sensitivity limits its utility. Here, we developed the second-generation GPCR-activation-based NE sensors (GRABNE2m and GRABNE2h) with a superior response and high sensitivity and selectivity to NE both in vitro and in vivo. Notably, these sensors can detect NE release triggered by either optogenetic or behavioral stimuli in freely moving mice, producing robust signals in the locus coeruleus and hypothalamus. With the development of a novel transgenic mouse line, we recorded both NE release and calcium dynamics with dual-color fiber photometry throughout the sleep-wake cycle; moreover, dual-color mesoscopic imaging revealed cell-type-specific spatiotemporal dynamics of NE and calcium during sensory processing and locomotion. Thus, these new GRABNE sensors are valuable tools for monitoring the precise spatiotemporal release of NE in vivo, providing new insights into the physiological and pathophysiological roles of NE.

Intact gesture cueing of attention but attenuated sensitivity to peripheral social targets in autistic children: An eye-tracking and pupillometric study

BACKGROUND

Altered automatic attention cueing has been reported in autistic children. Yet less is known about how autistic children would respond when the social cue that directs attention occurs in an implied social interaction.

METHODS

By using eye-tracking, the current study examined orienting responses to a socially-relevant target or a nonsocial target cued by a goal-directed social gesture in autistic children. Saccadic reaction time and pupillary responses were employed to measure gaze behavior and physiological arousal of autistic children.

RESULTS

Both groups of children showed reflexive orienting to the target regardless of its sociality, whereas typically developing (TD) children exhibited faster gaze shift than autistic children when the target was a social stimulus. An increased pupil dilation was observed in autistic children in response to stimuli relative to TD children. Further, autistic children showed larger baseline pupil response.

CONCLUSIONS

Autistic children show attenuated sensitivity to social targets and atypical pupil responses, which may be due to the dysfunction of locus coeruleus (LC) - norepinephrine (NE) system.

Influence of maternal immune activation on autism-like symptoms and coping strategies in male offspring

Maternal immune activation (MIA) caused by exposure to pathogens or inflammation during critical periods of gestation increased susceptibility to neurodevelopmental disorders, including autism, in the offspring. In the present work, we aimed to provide characterization of the long-term consequences on anxiety-like behavior and cardiovascular stress response of MIA in the offspring. This study aimed to evaluate the effect of MIA by lipopolysaccharide (LPS) in adult male offspring. In our study, the animals were subjected to a range of behavioral and physiological tests, including the elevated plus maze, social interaction, cat odor response, open field behavior, contextual fear conditioning, and cardiovascular responses during restraint stress. In the offspring of MIA, our study unveiled distinct anxious behaviors. This was evident by fewer entries into the open arms of the maze, diminished anti-thigmotaxis in the open field, and a decrease in social interaction time. Moreover, these rats showed heightened sensitivity to cat odor, exhibited prolonged freezing during fear conditioning, and presented elevated 22 Hz ultrasonic vocalizations. Notably, during restraint stress, these animals manifested an augmented blood pressure response, and this was associated with an increase in c-fos expression in the locus coeruleus compared to the control group. These findings collectively underline the extensive behavioral and physiological alterations stemming from MIA. This study deepens our understanding of the significance of maternal health in predisposing offspring to neurobehavioral deficits and psychiatric disorders.

Temperament and probabilistic predictive coding in visual-spatial attention

Cholinergic (Ach), Noradrenergic (NE), and Dopaminergic (DA) pathways play an important role in the regulation of spatial attention. The same neurotransmitters are also responsible for inter-individual differences in temperamental traits. Here we explored whether biologically defined temperamental traits determine differences in the ability to orient spatial attention as a function of the probabilistic association between cues and targets. To this aim, we administered the Structure of Temperament Questionnaire (STQ-77) to a sample of 151 participants who also performed a Posner task with central endogenous predictive (80 % valid/20 % invalid) or non-predictive cues (50 % valid/50 % invalid). We found that only participants with high scores in Plasticity and Intellectual Endurance showed a selective abatement of attentional costs with non-predictive cues. In addition, stepwise regression showed that costs in the non-predictive condition were negatively predicted by scores in Plasticity and positively predicted by scores in Probabilistic Thinking. These results show that stable temperamental characteristics play an important role in defining the inter-individual differences in attentional behaviour, especially in the presence of different probabilistic organisations of the sensory environment. These findings emphasize the importance of considering temperamental and personality traits in social and professional environments where the ability to control one's attention is a crucial functional skill.

Manipulation of phasic arousal by auditory cues is associated with subsequent changes in visual orienting to faces in infancy

This eye-tracking study investigated the effect of sound-induced arousal on social orienting under different auditory cue conditions in 5-month-old (n = 25; n = 13 males) and 10-month-old infants (n = 21; n = 14 males) participating in a spontaneous visual search task. Results showed: (1) larger pupil dilation discriminating between high and low volume (b = 0.02, p = 0.007), but not between social and non-social sounds (b = 0.004, p = 0.64); (2) faster visual orienting (b =  - 0.09, p < 0.001) and better social orienting at older age (b = 0.94, p < 0.001); (3) a fast habituation effect on social orienting after high-volume sounds (χ2(2) = 7.39, p = 0.025); (4) a quadratic association between baseline pupil size and target selection (b =  - 1.0, SE = 0.5, χ2(1) = 4.04, p = 0.045); (5) a positive linear association between pupil dilation and social orienting (b = 0.09, p = 0.039). Findings support adaptive gain theories of arousal, extending the link between phasic pupil dilation and task performance to spontaneous social orienting in infancy.

Exploring the Role of Locus Coeruleus in Alzheimer's Disease: a Comprehensive Update on MRI Studies and Implications

PURPOSE OF REVIEW

Performing a thorough review of magnetic resonance imaging (MRI) studies assessing locus coeruleus (LC) integrity in ageing and Alzheimer's disease (AD), and contextualizing them with current preclinical and neuropathological literature.

RECENT FINDINGS

MRI successfully detected LC alterations in ageing and AD, identifying degenerative phenomena involving this nucleus even in the prodromal stages of the disorder. The degree of LC disruption was also associated with the severity of AD cortical pathology, cognitive and behavioral impairment, and the risk of clinical progression. Locus coeruleus-MRI has proved to be a useful tool to assess the integrity of the central noradrenergic system in vivo in humans. It allowed to test in patients preclinical and experimental hypothesis, thus confirming the specific and marked involvement of the LC in AD and its key pathogenetic role. Locus coeruleus-MRI-related data might represent the theoretical basis on which to start developing noradrenergic drugs to target AD.

Prediction error and memory across the lifespan

The influence of Prediction Errors (PEs) on episodic memory has generated growing empirical and theoretical interest. This review explores how the relationship between PE and memory may evolve throughout lifespan. Drawing upon the predictive processing framework and the Predictive, Interactive Multiple Memory System (PIMMS) model in particular, the paper highlights the hierarchical organization of memory systems and the interaction between top-down predictions and bottom-up sensory input, proposing that PEs promote synaptic change and improve encoding and consolidation processes. We discuss the neuroscientific mechanisms underlying PE-driven memory enhancement, focusing on the involvement of the hippocampus, the entorhinal cortex-hippocampus pathway, and the noradrenergic sympathetic system. Recognizing the divergent trajectories of episodic and semantic memory across the lifespan is crucial when examining the effects of PEs on memory. This review underscores the heterogeneity of memory processes and neurocognitive mechanisms underlying PE-driven memory enhancement across age. Future research is suggested to directly compare neural networks involved in learning from PEs across different age groups and to contribute to a deeper understanding of PE-driven learning across age.

Elevated and accelerated: Locus coeruleus activity and visual search abilities in autistic children

BACKGROUND

Autistic individuals excel at visual search, however, the neural mechanism(s) underlying this advantage remain unclear. The locus coeruleus-norepinephrine (LC-NE) system, which plays a critical role in sensory perception and selective attention, has been shown to function in a persistently elevated state in individuals on the spectrum. However, the relationship between elevated tonic LC-NE activity and accelerated search in autism has not been explored.

OBJECTIVE

To examine the relationship between visual search abilities and resting pupil diameter (an indirect measure of tonic LC-NE activation) in autistic and neurotypical children.

METHODS

Participants were 24 school-aged autistic children and 24 age- and IQ-matched neurotypical children aged 8-15 years. Children completed two tasks: a resting eye-tracking task and a visual search paradigm. For the resting eye-tracking task, pupil diameter was monitored while participants fixated a central crosshair. For the visual search paradigm, participants were instructed to find the target (vertical line) embedded within an array of tilted (10°) distractor lines. The target was present on 50% of trials, and displayed within set sizes of 18, 24, and 36 items.

RESULTS

Consistent with previous studies, autistic children had significantly larger resting pupil size and searched faster and more efficiently compared to their neurotypical peers. Eye-tracking findings revealed that accelerated search was associated with fewer, not shorter, fixations in the autism group. Autistic children also showed reduced leftward search bias. Larger resting pupil size, indicative of increased tonic activation of the LC-NE system, was associated with greater search efficiency, longer fixation durations, and reduced leftward bias. Finally, within both groups reduced leftward bias was associated with increased autism symptomatology.

DISCUSSION

Together, these findings add to the existing body of research highlighting superior search in autism, suggest that elevated tonic LC-NE activity may contribute to more efficient search, and link non-social visual-spatial processing strengths to autism symptoms.

A systematic review and meta-analysis on the ocular characteristics in children and adolescents with neurodevelopmental disorders

To conduct a systematic review and meta-analysis of the association between children and adolescents with attention deficit hyperactivity disorder (ADHD) or autism spectrum disorder (ASD) and ocular characteristics. Systematic review with meta-analysis. Six databases (PubMed, Scopus, APA PsycInfo, Embase, EBSCOhost, and Cochrane library) were selected for a systematic literature search from database inception to July 2022. The observational studies assessing and reporting at least one outcome regarding ocular characteristics in children and adolescents with ADHD or ASD aged 6-17 were included. Studies in languages other than English, studies of adult or elderly human populations, and animal studies were excluded. The results were analyzed following the PRISMA guideline 2020. The findings of 15 studies, including 433 participants with ADHD, 253 participants with ASD, and 514 participants with typical development (TD), revealed that there were no significant differences in retinal nerve fiber layer, ganglion cell complex, and macular thickness between the ADHD group and the TD group. In subgroup analysis, significant differences in inferior ganglion cell (MD = - 3.19; 95% CI = [- 6.06, - 0.31], p = 0.03) and nasal macular thickness (MD = 5.88; 95% CI = [- 0.01, 11.76], p = 0.05) were detected between the ADHD group and the TD group. A significant difference in pupillary light reflex (PLR) was also observed between the ASD group and the TD group (MD = 29.7; 95% CI = [18.79, 40.63], p < 0.001). Existing evidence suggests a possible association between children and adolescents with ADHD or ASD and ocular characteristics. Given the limited number of studies, further research on a larger cohort is necessary to claim a possible diagnosis of ADHD or ASD through ocular characteristics.

Cognitive-Affective Functions of the Cerebellum

The cerebellum, traditionally associated with motor coordination and balance, also plays a crucial role in various aspects of higher-order function and dysfunction. Emerging research has shed light on the cerebellum's broader contributions to cognitive, emotional, and reward processes. The cerebellum's influence on autonomic function further highlights its significance in regulating motivational and emotional states. Perturbations in cerebellar development and function have been implicated in various neurodevelopmental disorders, including autism spectrum disorder and attention deficit hyperactivity disorder. An increasing appreciation for neuropsychiatric symptoms that arise from cerebellar dysfunction underscores the importance of elucidating the circuit mechanisms that underlie complex interactions between the cerebellum and other brain regions for a comprehensive understanding of complex behavior. By briefly discussing new advances in mapping cerebellar function in affective, cognitive, autonomic, and social processing and reviewing the role of the cerebellum in neuropathology beyond the motor domain, this Mini-Symposium review aims to provide a broad perspective of cerebellar intersections with the limbic brain in health and disease.

Deficits in the pupillary response associated with abnormal visuospatial attention allocation in mild traumatic brain injury

INTRODUCTION

The ability to allocate visual attention is known to be impaired in patients with mild traumatic brain injury (mTBI). In the present study, we investigated a possible neural correlate of this cognitive deficit by examining the pupil response of patients with mTBI whilst performing a modified Posner visual search task.

METHOD

Two experiments were conducted in which the target location was either not cued (Experiment 1) or cued (Experiment 2). Additionally, in Experiment 2, the type of cue (endogenous vs exogenous cue) and cue validity were treated as independent variables. In both experiments, search efficiency was varied by changing shape similarity between target and distractor patterns. The reaction time required to judge whether the target was present or absent and pupil dilation metrics, particularly the pupil dilation latency (PDL) and amplitude (PDA), were measured. Thirteen patients with chronic mTBI and 21 age-, sex-, and IQ -matched controls participated in the study.

RESULTS

In Experiment 1, patients with mTBI displayed a similar PDA for both efficient and inefficient search conditions, while control participants had a significantly larger PDA in inefficient search conditions compared to efficient search conditions. As cognitive load is positively correlated with PDA, our findings suggest that mTBI patients were unable to apply more mental effort whilst performing visual search, particularly if the task is difficult when visual search is inefficient. In Experiment 2, when the target location was cued, patients with mTBI displayed no significant pupil dilation response to the target regardless of the efficiency of the search, nor whether the cue was valid or invalid. These results contrasted with control participants, who were additionally sensitive to the validity of the cue in which PDA was smaller for cue-valid conditions than invalid conditions, particularly for efficient search conditions.

CONCLUSION

Pupillometry provided further evidence of attention allocation deficits following mTBI.

Pupil-linked arousal modulates network-level EEG signatures of attention reorienting during immersive multitasking

Objective. When multitasking, we must dynamically reorient our attention between different tasks. Attention reorienting is thought to arise through interactions of physiological arousal and brain-wide network dynamics. In this study, we investigated the relationship between pupil-linked arousal and electroencephalography (EEG) brain dynamics in a multitask driving paradigm conducted in virtual reality. We hypothesized that there would be an interaction between arousal and EEG dynamics and that this interaction would correlate with multitasking performance.Approach. We collected EEG and eye tracking data while subjects drove a motorcycle through a simulated city environment, with the instructions to count the number of target images they observed while avoiding crashing into a lead vehicle. The paradigm required the subjects to continuously reorient their attention between the two tasks. Subjects performed the paradigm under two conditions, one more difficult than the other.Main results. We found that task difficulty did not strongly correlate with pupil-linked arousal, and overall task performance increased as arousal level increased. A single-trial analysis revealed several interesting relationships between pupil-linked arousal and task-relevant EEG dynamics. Employing exact low-resolution electromagnetic tomography, we found that higher pupil-linked arousal led to greater EEG oscillatory activity, especially in regions associated with the dorsal attention network and ventral attention network (VAN). Consistent with our hypothesis, we found a relationship between EEG functional connectivity and pupil-linked arousal as a function of multitasking performance. Specifically, we found decreased functional connectivity between regions in the salience network (SN) and the VAN as pupil-linked arousal increased, suggesting that improved multitasking performance at high arousal levels may be due to a down-regulation in coupling between the VAN and the SN. Our results suggest that when multitasking, our brain rebalances arousal-based reorienting so that individual task demands can be met without prematurely reorienting to competing tasks.

Familiarization with Mixed Reality for Individuals with Autism Spectrum Disorder: An Eye Tracking Study

Mixed Reality (MR) technology is experiencing significant growth in the industrial and healthcare sectors. The headset HoloLens 2 displays virtual objects (in the form of holograms) in the user's environment in real-time. Individuals with Autism Spectrum Disorder (ASD) exhibit, according to the DSM-5, persistent deficits in communication and social interaction, as well as a different sensitivity compared to neurotypical (NT) individuals. This study aims to propose a method for familiarizing eleven individuals with severe ASD with the HoloLens 2 headset and the use of MR technology through a tutorial. The secondary objective is to obtain quantitative learning indicators in MR, such as execution speed and eye tracking (ET), by comparing individuals with ASD to neurotypical individuals. We observed that 81.81% of individuals with ASD successfully familiarized themselves with MR after several sessions. Furthermore, the visual activity of individuals with ASD did not differ from that of neurotypical individuals when they successfully familiarized themselves. This study thus offers new perspectives on skill acquisition indicators useful for supporting neurodevelopmental disorders. It contributes to a better understanding of the neural mechanisms underlying learning in MR for individuals with ASD.

Intraneuronal accumulation of amyloid-β peptides as the pathomechanism linking autism and its co-morbidities: epilepsy and self-injurious behavior - the hypothesis

Autism spectrum disorder (ASD) is associated with enhanced processing of amyloid-β precursor protein (APP) by secretase-α, higher blood levels of sAPPα and intraneuronal accumulation of N-terminally truncated Aβ peptides in the brain cortex - mainly in the GABAergic neurons expressing parvalbumin - and subcortical structures. Brain Aβ accumulation has been also described in epilepsy-the frequent ASD co-morbidity. Furthermore, Aβ peptides have been shown to induce electroconvulsive episodes. Enhanced production and altered processing of APP, as well as accumulation of Aβ in the brain are also frequent consequences of traumatic brain injuries which result from self-injurious behaviors, another ASD co-morbidity. We discuss distinct consequences of accumulation of Aβ in the neurons and synapses depending on the Aβ species, their posttranslational modifications, concentration, level of aggregation and oligomerization, as well as brain structures, cell types and subcellular structures where it occurs. The biological effects of Aβ species which are discussed in the context of the pathomechanisms of ASD, epilepsy, and self-injurious behavior include modulation of transcription-both activation and repression; induction of oxidative stress; activation and alteration of membrane receptors' signaling; formation of calcium channels causing hyper-activation of neurons; reduction of GABAergic signaling - all of which lead to disruption of functions of synapses and neuronal networks. We conclude that ASD, epilepsy, and self-injurious behaviors all contribute to the enhanced production and accumulation of Aβ peptides which in turn cause and enhance dysfunctions of the neuronal networks that manifest as autism clinical symptoms, epilepsy, and self-injurious behaviors.

Sleep disturbances in autism spectrum disorder: Animal models, neural mechanisms, and therapeutics

Sleep is crucial for brain development. Sleep disturbances are prevalent in children with autism spectrum disorder (ASD). Strikingly, these sleep problems are positively correlated with the severity of ASD core symptoms such as deficits in social skills and stereotypic behavior, indicating that sleep problems and the behavioral characteristics of ASD may be related. In this review, we will discuss sleep disturbances in children with ASD and highlight mouse models to study sleep disturbances and behavioral phenotypes in ASD. In addition, we will review neuromodulators controlling sleep and wakefulness and how these neuromodulatory systems are disrupted in animal models and patients with ASD. Lastly, we will address how the therapeutic interventions for patients with ASD improve various aspects of sleep. Together, gaining mechanistic insights into the neural mechanisms underlying sleep disturbances in children with ASD will help us to develop better therapeutic interventions.

Pupil dilation reflects the dynamic integration of audiovisual emotional speech

Emotional speech perception is a multisensory process. When speaking with an individual we concurrently integrate the information from their voice and face to decode e.g., their feelings, moods, and emotions. However, the physiological reactions-such as the reflexive dilation of the pupil-associated to these processes remain mostly unknown. That is the aim of the current article, to investigate whether pupillary reactions can index the processes underlying the audiovisual integration of emotional signals. To investigate this question, we used an algorithm able to increase or decrease the smiles seen in a person's face or heard in their voice, while preserving the temporal synchrony between visual and auditory channels. Using this algorithm, we created congruent and incongruent audiovisual smiles, and investigated participants' gaze and pupillary reactions to manipulated stimuli. We found that pupil reactions can reflect emotional information mismatch in audiovisual speech. In our data, when participants were explicitly asked to extract emotional information from stimuli, the first fixation within emotionally mismatching areas (i.e., the mouth) triggered pupil dilation. These results reveal that pupil dilation can reflect the dynamic integration of audiovisual emotional speech and provide insights on how these reactions are triggered during stimulus perception.

Eye-movement indices of arousal predict ADHD and comorbid externalizing symptoms over a 2-year period

Attention-deficit/hyperactivity disorder (ADHD) follows a variable course across childhood. Disrupted arousal has been hypothesized to underlie core symptoms as well as comorbid internalizing and externalizing conditions. The current study examined eye-movement and pupil-dilation metrics indexing arousal as longitudinal predictors of ADHD, externalizing, and internalizing symptoms over a 2-year period. Participants aged 8-13 years (N = 54, 30% with a diagnosis of ADHD) completed a modified version of the gap-overlap task including arousal-inducing auditory warning signals. Parents rated symptoms at the time of testing and at 2 years follow-up. Phasic alerting (reaction-time reduction after alerting cues) is an index of arousal. Here, larger phasic alerting effects predicted higher ADHD-symptom levels 2 years later. Blunted pupil-dilation responses predicted externalizing symptoms at T2, controlling for ADHD and externalizing at T1. Our results support the theory that ADHD is associated with altered arousal. Blunted arousal reactivity may be a longitudinal risk factor for externalizing problems in children with ADHD symptoms.

The Central Noradrenergic System in Neurodevelopmental Disorders: Merging Experimental and Clinical Evidence

The aim of this article is to highlight the potential role of the locus-coeruleus-noradrenergic (LC-NA) system in neurodevelopmental disorders (NdDs). The LC is the main brain noradrenergic nucleus, key in the regulation of arousal, attention, and stress response, and its early maturation and sensitivity to perinatal damage make it an interesting target for translational research. Clinical data shows the involvement of the LC-NA system in several NdDs, suggesting a pathogenetic role in the development of such disorders. In this context, a new neuroimaging tool, LC Magnetic Resonance Imaging (MRI), has been developed to visualize the LC in vivo and assess its integrity, which could be a valuable tool for exploring morphological alterations in NdD in vivo in humans. New animal models may be used to test the contribution of the LC-NA system to the pathogenic pathways of NdD and to evaluate the efficacy of NA-targeting drugs. In this narrative review, we provide an overview of how the LC-NA system may represent a common pathophysiological and pathogenic mechanism in NdD and a reliable target for symptomatic and disease-modifying drugs. Further research is needed to fully understand the interplay between the LC-NA system and NdD.

Pupillary motility responses to affectively salient stimuli in individuals with depression or elevated risk of depression: A systematic review and meta-analysis

Elaborative affective processing is observed in depression, and pupillary reactivity, a continuous, sensitive, and reliable indicator of physiological arousal and neurocognitive processing, is increasingly utilized in studies of depression-related characteristics. As a first attempt to quantitively summarize existing evidence on depression-related pupillary reactivity alterations, this review and meta-analysis evaluated the direction, magnitude, and specificity of pupillary indices of affective processing towards positively, negatively, and neutrally-valenced stimuli among individuals diagnosed with depression or with elevated risk of depression. Studies on pupillary responses to affective stimuli in the target groups were identified in PsycINFO and PubMed databases. Twenty-two articles met inclusion criteria for the qualitative review and 16 for the quantitative review. Three-level frequentist and Bayesian models were applied to summarize pooled effects from baseline-controlled stimuli-induced average changes in pupillary responses. In general, compared to non-depressed individuals, individuals with depression or elevated risk of depression exhibited higher pupillary reactivity (d =0.15) towards negatively-valenced stimuli during affective processing. Pupillary motility towards negatively-valenced stimuli may be a promising trait-like marker for depression vulnerability.

Sensory salience processing moderates attenuated gazes on faces in autism spectrum disorder: a case-control study

BACKGROUND

Attenuated social attention is a key marker of autism spectrum disorder (ASD). Recent neuroimaging findings also emphasize an altered processing of sensory salience in ASD. The locus coeruleus-norepinephrine system (LC-NE) has been established as a modulator of this sensory salience processing (SSP). We tested the hypothesis that altered LC-NE functioning contributes to different SSP and results in diverging social attention in ASD.

METHODS

We analyzed the baseline eye-tracking data of the EU-AIMS Longitudinal European Autism Project (LEAP) for subgroups of autistic participants (n = 166, age = 6-30 years, IQ = 61-138, gender [female/male] = 41/125) or neurotypical development (TD; n = 166, age = 6-30 years, IQ = 63-138, gender [female/male] = 49/117) that were matched for demographic variables and data quality. Participants watched brief movie scenes (k = 85) depicting humans in social situations (human) or without humans (non-human). SSP was estimated by gazes on physical and motion salience and a corresponding pupillary response that indexes phasic activity of the LC-NE. Social attention is estimated by gazes on faces via manual areas of interest definition. SSP is compared between groups and related to social attention by linear mixed models that consider temporal dynamics within scenes. Models are controlled for comorbid psychopathology, gaze behavior, and luminance.

RESULTS

We found no group differences in gazes on salience, whereas pupillary responses were associated with altered gazes on physical and motion salience. In ASD compared to TD, we observed pupillary responses that were higher for non-human scenes and lower for human scenes. In ASD, we observed lower gazes on faces across the duration of the scenes. Crucially, this different social attention was influenced by gazes on physical salience and moderated by pupillary responses.

LIMITATIONS

The naturalistic study design precluded experimental manipulations and stimulus control, while effect sizes were small to moderate. Covariate effects of age and IQ indicate that the findings differ between age and developmental subgroups.

CONCLUSIONS

Pupillary responses as a proxy of LC-NE phasic activity during visual attention are suggested to modulate sensory salience processing and contribute to attenuated social attention in ASD.

Cellular composition and circuit organization of the locus coeruleus of adult mice

The locus coeruleus (LC) houses the vast majority of noradrenergic neurons in the brain and regulates many fundamental functions, including fight and flight response, attention control, and sleep/wake cycles. While efferent projections of the LC have been extensively investigated, little is known about its local circuit organization. Here, we performed large-scale multipatch recordings of noradrenergic neurons in adult mouse LC to profile their morpho-electric properties while simultaneously examining their interactions. LC noradrenergic neurons are diverse and could be classified into two major morpho-electric types. While fast excitatory synaptic transmission among LC noradrenergic neurons was not observed in our preparation, these mature LC neurons connected via gap junction at a rate similar to their early developmental stage and comparable to other brain regions. Most electrical connections form between dendrites and are restricted to narrowly spaced pairs or small clusters of neurons of the same type. In addition, more than two electrically coupled cell pairs were often identified across a cohort of neurons from individual multicell recording sets that followed a chain-like organizational pattern. The assembly of LC noradrenergic neurons thus follows a spatial and cell-type-specific wiring principle that may be imposed by a unique chain-like rule.

Atypical Arousal Regulation in Children With Autism but Not With Attention-Deficit/Hyperactivity Disorder as Indicated by Pupillometric Measures of Locus Coeruleus Activity

BACKGROUND

Atypical arousal regulation may explain slower mean reaction time (MRT) in autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder compared with typical development. The locus coeruleus-norepinephrine system (LC-NE) underlies arousal regulation and adapts its activity to the utility of a task. LC-NE tonic and phasic activity are indexed by baseline pupil size (BPS) and stimulus-evoked pupillary response (SEPR).

METHODS

The study assessed pupillometry in ASD (n = 31, 3 female/28 male), attention-deficit/hyperactivity disorder (n = 28, 3 female/25 male), and typically developing control subjects (n = 31, 16 female/15 male) during a visuospatial reaction-time task that manipulates arousal by conditions with low and high task utility. We estimated linear mixed models of BPS, SEPR, and MRT in a per-trial analysis to investigate arousal regulation of task performance.

RESULTS

Slower MRT occurred in the ASD group compared with the typically developing control group during low-utility conditions while controlling for dimensional ASD and attention-deficit/hyperactivity disorder symptoms. In low-utility conditions, BPS and SEPR were inversely related and both were associated with faster MRT. Increased ASD symptoms across groups were associated with higher BPS during low-utility conditions. Changes in BPS and SEPR between task-utility conditions were smaller in the ASD group.

CONCLUSIONS

Slower visuospatial task performance in ASD is specific to low task utility. Arousal was associated with task performance and showed altered activity in ASD. Increased BPS during low-utility conditions suggested increased LC-NE tonic activity as an ASD symptom marker in children. Smaller changes in BPS and SEPR in ASD indicated attenuated LC-NE activity adaptation in response to high-utility conditions. Slower performance and atypical arousal regulation are probably associated with attenuated LC-NE activity adaptation.

The effects of stimulant and non-stimulant medications on the autonomic nervous system (ANS) functioning in people with ADHD: A systematic review and meta-analysis

We carried out a systematic review and meta-analysis to investigate the effects of stimulant and non-stimulant medications on autonomic functioning in people with ADHD (PROSPERO: CRD42020212439). We searched (9th August 2021) PsycInfo, MEDLINE, EMBASE, Web of Science and The Cochrane Library, for randomised and non-randomised studies reporting indices of autonomic activity, (electrodermal, pupillometry and cardiac), pre- and post-medication exposure in people meeting DSM/ICD criteria for ADHD. In the narrative syntheses, we included 5 electrodermal studies, 1 pupillometry study and 57 studies investigating heart rate and blood pressure. In the meta-analyses, 29 studies were included on blood pressure and 32 on heart rate. Administration of stimulants, and to a lesser degree, non-stimulants increased heart rate and blood pressure in people with ADHD. Similarly, an upregulation of arousal, reflected in increased electrodermal activity and pupil diameter was observed following stimulant use. Yet, the methodological diversity of studies presented in this review reinforces the need for more standardised and rigorous research to fully understand the relationship between arousal, medication, and behaviour in ADHD.

Measures of tonic and phasic activity of the locus coeruleus-norepinephrine system in children with autism spectrum disorder: An event-related potential and pupillometry study

A growing body of research suggests that locus coeruleus-norepinephrine (LC-NE) system may function differently in individuals with autism spectrum disorder (ASD). Understanding the dynamics of both tonic (resting pupil diameter) and phasic (pupil dilation response [PDR] and event-related potential [ERP]) indices may provide meaningful insights about the nature of LC-NE function in ASD. Twenty-four children with ASD and 27 age- and nonverbal-IQ matched typically developing (TD) children completed two experiments: (1) a resting eye-tracking task to measure tonic pupil diameter, and (2) a three-stimulus oddball paradigm to measure phasic responsivity using PDR and ERP. Consistent with prior reports, our results indicate that children with ASD exhibit increased tonic (resting pupil diameter) and reduced phasic (PDR and ERP) activity of the LC-NE system compared to their TD peers. For both groups, decreased phasic responsivity was associated with increased resting pupil diameter. Lastly, tonic and phasic LC-NE indices were primarily related to measures of attention-deficit/hyperactivity disorder (ADHD), and not ASD, symptomatology. These findings expand our understanding of neurophysiological differences present in ASD and demonstrate that aberrant LC-NE activation may be associated with atypical arousal and decreased responsivity to behaviorally-relevant information in ASD.

Arousal-modulated memory encoding and retrieval in adults with autism spectrum disorder

Recently, we have shown that pupil dilation during a recognition memory task can serve as an index of memory retrieval difficulties in autism. At the time of publication, we were unaware of specific data-analysis methods that can be used to shed further light on the origins of such memory related pupil dilation. Specifically, by distinguishing "tonic" from "phasic" changes in pupil dilation and considering their temporal progression, it is possible to draw inferences about the functional integrity of a locus coeruleus-norepinephrine system (LC-NE) that is known to play a key role in regulating memory encoding and retrieval processes. We therefore apply these analyses to our previously published eye-tracking data of adults with ASD (N = 24) and neurotypical development (TD, N = 30) during the recognition memory task. In this re-analysis, we related pupil dilation during encoding and retrieval to recognition accuracy in a per-trial analysis of linear mixed models. In ASD, we replicated attenuated recognition accuracy, which was accompanied by attenuated pupil dilation during encoding and retrieval. Group differences in pupil dilation during retrieval occurred late during the trial (after 1.75 s) and indicated an altered top-down processing like attenuated attribution of semantic salience in response to previously encoded stimuli. In addition, only in the ASD group were higher pupil dilation during encoding and lower pupil dilation during retrieval associated with decreased recognition accuracy. This supports altered modulation of memory encoding and retrieval in ASD, with LC-NE phasic activity as promising underlying mechanism. LAY SUMMARY: We investigated the changes of pupil size during memory testing in autism spectrum disorder. Adults with ASD remembered fewer items correctly than neurotypical individuals (TD). This reduced memory was related to increased pupillary responses at study and decreased pupil dilation at test only for adults with ASD indicating a different modulation of memory by the locus coeruleus.

Larger pupil dilation to nonsocial sounds in infants with subsequent autism diagnosis

BACKGROUND

Studies of infants with an elevated likelihood of autism spectrum disorder can identify basic developmental processes that are associated with subsequently emerging clinical symptoms. Atypical responsiveness to sounds in infancy is such a potential early marker of autism. Here, we used pupillometry to quantify reactivity to social and nonsocial sounds in infants with a subsequent diagnosis. Previous research suggest that pupil dilation reflects attentional alerting, and link it to the locus coeruleus norepinephrine system.

METHODS

We measured pupil dilation responses to child-directed speech and the sound of running water; sounds infants often hear in their everyday life. The final sample consisted of 99 ten-month-old infants (52 girls), of whom 68 had an elevated likelihood of autism and 31 were typically developing low-likelihood infants. At follow-up (36 months of age), 18 children in the elevated-likelihood group were diagnosed with autism.

RESULTS

Compared to infants without diagnosis, the infants who were subsequently diagnosed with autism had larger pupil dilation when listening to nonsocial sounds, while reactivity to speech was strikingly similar between groups. In the total sample, more pupil dilation to the nonsocial sound was associated with higher levels of autistic symptoms. We also found that on a trial-by-trial basis, across all conditions and groups, more pupil dilation was associated with making fewer gaze shifts.

CONCLUSIONS

This study did not find evidence of atypical pupillary reactivity to child-directed speech early in life in autism. Instead, the results suggest that certain nonsocial sounds elicit atypically strong alerting responses in infants with a subsequent autism diagnosis. These findings may have important theoretical and clinical implications.

Recent insights into respiratory modulation of brain activity offer new perspectives on cognition and emotion

Over the past six years, a rapidly growing number of studies have shown that respiration exerts a significant influence on sensory, affective, and cognitive processes. At the same time, an increasing amount of experimental evidence indicates that this influence occurs via modulation of neural oscillations and their synchronization between brain areas. In this article, we review the relevant findings and discuss whether they might inform our understanding of a variety of disorders that have been associated with abnormal patterns of respiration. We review literature on the role of respiration in chronic obstructive pulmonary disease (COPD), anxiety (panic attacks), and autism spectrum disorder (ASD), and we conclude that the new insights into respiratory modulation of neuronal activity may help understand the relationship between respiratory abnormalities and cognitive and affective deficits.

Intolerance of Uncertainty and Challenges in Decision-making in Adults with High-Functioning Autism

<p style="text-align: justify;">Individuals with high-functioning autism have difficulties in decision-making in face of incomplete or ambiguous information, particularly in the context of social interaction. Tasks demanding an immediate response or deviation from the usual behavior make them feel excessive anxiety which restricts their social and professional activity. Attempts to camouflage their conservatism to others are one of the risk factors for comorbid depression. Therefore, they avoid new and non-routine situations, thus restricting their own social activity and professional development. On the other hand, insisting on sameness and clarity may give individuals with autism an advantage in long-lasting monotonous tasks. The aim of this review is to consider these symptoms from the perspective of predictive coding. A range of experimental studies has shown that most of the subjects with autism have difficulty in predicting the outcomes based on the cumulative history of interacting with the environment, as well as updating expectations as new evidence becomes available. These peculiarities of the analysis and pragmatic weighting of information may cause the trait intolerance of uncertainty and novelty avoidance of most people with autism.</p>

Associations between the pupil light reflex and the broader autism phenotype in children and adults

The pupil light reflex (PLR), a marker of neuronal response to light, is a well-studied index of autonomic functioning. Studies have found that autistic children and adults have slower and weaker PLR responses compared to non-autistic peers, suggesting lower autonomic control. Altered autonomic control has also been associated with increased sensory difficulties in autistic children. With autistic traits varying in the general population, recent studies have begun to examine similar questions in non-autistic individuals. The current study looked at the PLR in relation to individual differences in autistic traits in non-autistic children and adults, asking how differences in the PLR could lead to variation in autistic traits, and how this might change across development. Children and adults completed a PLR task as a measure of sensitivity to light and autonomic response. Results showed that, in adults, increased levels of restricted and repetitive behaviors (RRB) were associated with a weaker and slower PLR. However, in children, PLR responses were not associated with autistic traits. Differences in PLR were also found across age groups, with adults showing smaller baseline pupil diameter and stronger PLR constriction as compared with children. The current study expanded on past work to examine the PLR and autistic traits in non-autistic children and adults, and the relevance of these findings to sensory processing difficulties is discussed. Future studies should continue to examine the neural pathways that might underlie the links between sensory processing and challenging behaviors.

Return of the Righting Reflex Does Not Portend Recovery of Cognitive Function in Anesthetized Rats

As the number of individuals undergoing general anesthesia rises globally, it becomes increasingly important to understand how consciousness and cognition are restored after anesthesia. In rodents, levels of consciousness are traditionally captured by physiological responses such as the return of righting reflex (RORR). However, tracking the recovery of cognitive function is comparatively difficult. Here we use an operant conditioning task, the 5-choice serial reaction time task (5-CSRTT), to measure sustained attention, working memory, and inhibitory control in male and female rats as they recover from the effects of several different clinical anesthetics. In the 5-CSRTT, rats learn to attend to a five-windowed touchscreen for the presentation of a stimulus. Rats are rewarded with food pellets for selecting the correct window within the time limit. During each session we tracked both the proportion of correct (accuracy) and missed (omissions) responses over time. Cognitive recovery trajectories were assessed after isoflurane (2% for 1 h), sevoflurane (3% for 20 min), propofol (10 mg/kg I.V. bolus), ketamine (50 mg/kg I.V. infusion over 10 min), and dexmedetomidine (20 and 35 μg/kg I.V. infusions over 10 min) for up to 3 h following RORR. Rats were classified as having recovered accuracy performance when four of their last five responses were correct, and as having recovered low omission performance when they missed one or fewer of their last five trials. Following isoflurane, sevoflurane, and propofol anesthesia, the majority (63-88%) of rats recovered both accuracy and low omission performance within an hour of RORR. Following ketamine, accuracy performance recovers within 2 h in most (63%) rats, but low omission performance recovers in only a minority (32%) of rats within 3 h. Finally, following either high or low doses of dexmedetomidine, few rats (25-32%) recover accuracy performance, and even fewer (0-13%) recover low omission performance within 3 h. Regardless of the anesthetic, RORR latency is not correlated with 5-CSRTT performance, which suggests that recovery of neurocognitive function cannot be inferred from changes in levels of consciousness. These results demonstrate how operant conditioning tasks can be used to assess real-time recovery of neurocognitive function following different anesthetic regimens.

The Brainstem-Informed Autism Framework: Early Life Neurobehavioral Markers

Autism spectrum disorders (ASD) have long-term implications on functioning at multiple levels. In this perspective, we offer a brainstem-informed autism framework (BIAF) that traces the protracted neurobehavioral manifestations of ASD to early life brainstem dysfunctions. Early life brainstem-mediated markers involving functions of autonomic/arousal regulation, sleep-wake homeostasis, and sensorimotor integration are delineated. Their possible contributions to the early identification of susceptible infants are discussed. We suggest that the BIAF expands our multidimensional understanding of ASD by focusing on the early involvement of brainstem systems. Importantly, we propose an integrated BIAF screener that brings about the prospect of a sensitive and reliable early life diagnostic scheme for weighing the risk for ASD. The BIAF screener could provide clinicians substantial gains in the future and may carve customized interventions long before the current DSM ASD phenotype is manifested using dyadic co-regulation of brainstem-informed autism markers.

Development of the pupillary light reflex from 9 to 24 months: association with common autism spectrum disorder (ASD) genetic liability and 3-year ASD diagnosis

BACKGROUND

Although autism spectrum disorder (ASD) is heritable, the mechanisms through which genes contribute to symptom emergence remain unclear. Investigating candidate intermediate phenotypes such as the pupillary light reflex (PLR) prospectively from early in development could bridge genotype and behavioural phenotype.

METHODS

Using eye tracking, we longitudinally measured the PLR at 9, 14 and 24 months in a sample of infants (N = 264) enriched for a family history of ASD; 27 infants received an ASD diagnosis at 3 years. We examined the 9- to 24-month developmental trajectories of PLR constriction latency (onset; ms) and amplitude (%) and explored their relation to categorical 3-year ASD outcome, polygenic liability for ASD and dimensional 3-year social affect (SA) and repetitive/restrictive behaviour (RRB) traits. Polygenic scores for ASD (PGS_ASD ) were calculated for 190 infants.

RESULTS

While infants showed a decrease in latency between 9 and 14 months, higher PGS_ASD was associated with a smaller decrease in latency in the first year (β = -.16, 95% CI = -0.31, -0.002); infants with later ASD showed a significantly steeper decrease in latency (a putative 'catch-up') between 14 and 24 months relative to those with other outcomes (typical: β = .54, 95% CI = 0.08, 0.99; other: β = .53, 95% CI = 0.02, 1.04). Latency development did not associate with later dimensional variation in ASD-related traits. In contrast, change in amplitude was not related to categorical ASD or genetics, but decreasing 9- to 14-month amplitude was associated with higher SA (β = .08, 95% CI = 0.01, 0.14) and RRB (β = .05, 95% CI = 0.004, 0.11) traits.

CONCLUSIONS

These findings corroborate PLR development as possible intermediate phenotypes being linked to both genetic liability and phenotypic outcomes. Future work should incorporate alternative measures (e.g. functionally informed structural and genetic measures) to test whether distinct neural mechanisms underpin PLR alterations.

Attentional Disengagement and the Locus Coeruleus - Norepinephrine System in Children With Autism Spectrum Disorder

Background

Differences in non-social attentional functions have been identified as among the earliest features that distinguish infants later diagnosed with autism spectrum disorder (ASD), and may contribute to the emergence of core ASD symptoms. Specifically, slowed attentional disengagement and difficulty reorienting attention have been found across the lifespan in those at risk for, or diagnosed with, ASD. Additionally, the locus coeruleus-norepinephrine (LC-NE) system, which plays a critical role in arousal regulation and selective attention, has been shown to function atypically in ASD. While activity of the LC-NE system is associated with attentional disengagement and reorienting in typically developing (TD) individuals, it has not been determined whether atypical LC-NE activity relates to attentional disengagement impairments observed in ASD.

Objective

To examine the relationship between resting pupil diameter (an indirect measure of tonic LC-NE activation) and attentional disengagement in children with ASD.

Methods

Participants were 21 school-aged children with ASD and 20 age- and IQ-matched TD children. The study consisted of three separate experiments: a resting eye-tracking task and visual and auditory gap-overlap paradigms. For the resting eye-tracking task, pupil diameter was monitored while participants fixated a central crosshair. In the gap-overlap paradigms, participants were instructed to fixate on a central stimulus and then move their eyes to peripherally presented visual or auditory targets. Saccadic reaction times (SRT), percentage of no-shift trials, and disengagement efficiency were measured.

Results

Children with ASD had significantly larger resting pupil size compared to their TD peers. The groups did not differ for overall SRT, nor were there differences in SRT for overlap and gap conditions between groups. However, the ASD group did evidence impairments in disengagement (larger step/gap effects, higher percentage of no-shift trials, and reduced disengagement efficiency) compared to their TD peers. Correlational analyses showed that slower, less efficient disengagement was associated with increased pupil diameter.

Conclusion

Consistent with prior reports, children with ASD show significantly larger resting pupil diameter, indicative of atypically elevated tonic LC-NE activity. Associations between pupil size and measures of attentional disengagement suggest that atypically increased tonic activation of the LC-NE system may be associated with poorer attentional disengagement in children with ASD.

DNA methylome perturbations: an epigenetic basis for the emergingly heritable neurodevelopmental abnormalities associated with maternal smoking and maternal nicotine exposure†

Maternal smoking during pregnancy is associated with an ensemble of neurodevelopmental consequences in children and therefore constitutes a pressing public health concern. Adding to this burden, contemporary epidemiological and especially animal model research suggests that grandmaternal smoking is similarly associated with neurodevelopmental abnormalities in grandchildren, indicative of intergenerational transmission of the neurodevelopmental impacts of maternal smoking. Probing the mechanistic bases of neurodevelopmental anomalies in the children of maternal smokers and the intergenerational transmission thereof, emerging research intimates that epigenetic changes, namely DNA methylome perturbations, are key factors. Altogether, these findings warrant future research to fully elucidate the etiology of neurodevelopmental impairments in the children and grandchildren of maternal smokers and underscore the clear potential thereof to benefit public health by informing the development and implementation of preventative measures, prophylactics, and treatments. To this end, the present review aims to encapsulate the burgeoning evidence linking maternal smoking to intergenerational epigenetic inheritance of neurodevelopmental abnormalities, to identify the strengths and weaknesses thereof, and to highlight areas of emphasis for future human and animal model research therein.

Increased pupil dilation to happy faces in children with hyperactive/impulsive symptoms of ADHD

Attention-deficit/hyperactivity disorder (ADHD) is associated with disrupted emotional processes including impaired regulation of approach behavior and positive affect, irritability, and anger. Enhanced reactivity to emotional cues may be an underlying process. Pupil dilation is an indirect index of arousal, modulated by the autonomic nervous system and activity in the locus coeruleus-noradrenergic system. In the current study, pupil dilation was recorded while 8- to 12- year old children (n = 71, 26 with a diagnosis of ADHD and 45 typically developing), viewed images of emotional faces. Parent-rated hyperactive/impulsive symptoms were uniquely linked to higher pupil dilation to happy, but not fearful, angry, or neutral faces. This was not explained by comorbid externalizing symptoms. Together, these results suggest that hyperactive/impulsive symptoms are associated with hyperresponsiveness to approach-related emotional cues across a wide range of symptom severity.

Sex Differences in the Hypothalamic Oxytocin Pathway to Locus Coeruleus and Augmented Attention with Chemogenetic Activation of Hypothalamic Oxytocin Neurons

The tightly localized noradrenergic neurons (NA) in the locus coeruleus (LC) are well recognized as essential for focused arousal and novelty-oriented responses, while many children with autism spectrum disorder (ASD) exhibit diminished attention, engagement and orienting to exogenous stimuli. This has led to the hypothesis that atypical LC activity may be involved in ASD. Oxytocin (OXT) neurons and receptors are known to play an important role in social behavior, pair bonding and cognitive processes and are under investigation as a potential treatment for ASD. However, little is known about the neurotransmission from hypothalamic paraventricular (PVN) OXT neurons to LC NA neurons. In this study, we test, in male and female rats, whether PVN OXT neurons excite LC neurons, whether oxytocin is released and involved in this neurotransmission, and whether activation of PVN OXT neurons alters novel object recognition. Using "oxytocin sniffer cells" (CHO cells that express the human oxytocin receptor and a Ca indicator) we show that there is release of OXT from hypothalamic PVN OXT fibers in the LC. Optogenetic excitation of PVN OXT fibers excites LC NA neurons by co-release of OXT and glutamate, and this neurotransmission is greater in males than females. In male, but not in female animals, chemogenetic activation of PVN OXT neurons increases attention to novel objects.

Brain-based sex differences in autism spectrum disorder across the lifespan: A systematic review of structural MRI, fMRI, and DTI findings

Females with autism spectrum disorder (ASD) have been long overlooked in neuroscience research, but emerging evidence suggests they show distinct phenotypic trajectories and age-related brain differences. Sex-related biological factors (e.g., hormones, genes) may play a role in ASD etiology and have been shown to influence neurodevelopmental trajectories. Thus, a lifespan approach is warranted to understand brain-based sex differences in ASD. This systematic review on MRI-based sex differences in ASD was conducted to elucidate variations across the lifespan and inform biomarker discovery of ASD in females We identified articles through two database searches. Fifty studies met criteria and underwent integrative review. We found that regions expressing replicable sex-by-diagnosis differences across studies overlapped with regions showing sex differences in neurotypical cohorts. Furthermore, studies investigating age-related brain differences across a broad age-span suggest distinct neurodevelopmental patterns in females with ASD. Qualitative comparison across youth and adult studies also supported this hypothesis. However, many studies collapsed across age, which may mask differences. Furthermore, accumulating evidence supports the female protective effect in ASD, although only one study examined brain circuits implicated in "protection." When synthesized with the broader literature, brain-based sex differences in ASD may come from various sources, including genetic and endocrine processes involved in brain "masculinization" and "feminization" across early development, puberty, and other lifespan windows of hormonal transition. Furthermore, sex-related biology may interact with peripheral processes, in particular the stress axis and brain arousal system, to produce distinct neurodevelopmental patterns in males and females with ASD. Future research on neuroimaging-based sex differences in ASD would benefit from a lifespan approach in well-controlled and multivariate studies. Possible relationships between behavior, sex hormones, and brain development in ASD remain largely unexamined.

Delayed motor learning in a 16p11.2 deletion mouse model of autism is rescued by locus coeruleus activation

Children with autism spectrum disorder often exhibit delays in achieving motor developmental milestones such as crawling, walking and speech articulation. However, little is known about the neural mechanisms underlying motor-related deficits. Here, we reveal that mice with a syntenic deletion of the chromosome 16p11.2, a common copy number variation associated with autism spectrum disorder, also exhibit delayed motor learning without showing gross motor deficits. Using in vivo two-photon imaging in awake mice, we find that layer 2/3 excitatory neurons in the motor cortex of adult male 16p11.2-deletion mice show abnormally high activity during the initial phase of learning, and the process of learning-induced spine reorganization is prolonged. Pharmacogenetic activation of locus coeruleus noradrenergic neurons was sufficient to rescue the circuit deficits and the delayed motor learning in these mice. Our results unveil an unanticipated role of noradrenergic neuromodulation in improving the delayed motor learning in 16p11.2-deletion male mice.

Is autonomic function during resting-state atypical in Autism: A systematic review of evidence

BACKGROUND

Theories of differences in resting-state arousal in autistic individuals are influential. Differences in arousal during resting-state would impact engagement and adaptation to the environment, having a cascading effect on development of attentional and social skills.

OBJECTIVES

We systematically evaluated the evidence for differences in measures of autonomic arousal (heart rate, pupillometry or electrodermal activity) during resting-state in autistic individuals; to understand whether certain contextual or methodological factors impact reports of such differences.

DATA SOURCES

We searched PsycInfo, MEDLINE and EMBASE databases for papers published until 16th May 2019. Of 1207 titles initially identified, 60 met inclusion criteria.

RESULTS AND CONCLUSIONS

Of the 51 studies that investigated group differences between neurotypical and autistic participants, 60.8 % found evidence of group differences. While findings of hyperarousal were more common, particularly using indices of parasympathetic function, findings of hypo-arousal and autonomic dysregulation were also consistently present. Importantly, experimental context played a role in revealing such differences. The evidence is discussed with regard to important methodological factors and implications for future research are described.

The Association between Low Blood Pressure and Attention-Deficit Hyperactivity Disorder (ADHD) Observed in Children/Adolescents Does Not Persist into Young Adulthood. A Population-Based Ten-Year Follow-Up Study

Background: Attention-deficit hyperactivity disorder (ADHD) is one of the most common behavioral disorders in childhood and adolescence associated with relevant psychosocial impairments. The basic pathophysiology of ADHD may be related, at least partly, to a deficit in autonomic arousal processes, which not only influence core symptoms of the disorder, but may also lead to blood pressure (BP) deviations due to altered arousal regulation. Objectives: This study examined long-term changes in BP in children and adolescents with ADHD up to young adulthood. Methods: In children and adolescents aged between 7 and 17 years at baseline, we compared BP recordings in subjects with (n = 1219, 11.1%) and without (n = 9741, 88.9%) ADHD over a 10-year follow-up using data from the nationwide German Health Survey for Children and Adolescents (KiGGS). Propensity score matching was used to improve the comparability between children in the ADHD and control groups with now n = 1.190 in each group. Results: The results of these matched samples revealed that study participants with ADHD showed significantly lower systolic BP (107.6 ± 10.7 mmHg vs. 109.5 ± 10.9 mmHg, p < 0.001, Cohen’s d = 0.17) and diastolic BP (64.6 ± 7.5 mmHg vs. 65.8 ± 7.4 mmHg, p < 0.001, Cohen’s d = 0.16) at baseline. In a sensitivity analysis with a smaller (n = 272) and more stringently diagnosed ADHD group, the significant differences remained stable with somewhat higher Cohen’s d; i.e., 0.25 and 0.27, respectively. However, these differences did not persist after 10-year follow-up in a smaller matched longitudinal sub-group (ADHD n = 273; control n = 323), as subjects with and without ADHD had similar levels of systolic (123.4 ± 10.65 vs. 123.78 ± 11.1 mmHg, p = 0.675, Cohen’s d = 0.15) and diastolic BP (71.86 ± 6.84 vs. 71.85 ± 7.06 mmHg, p = 0.992, Cohen’s d = 0.16). Conclusions: At baseline, children and adolescents with ADHD had significantly lower BP (of small effect sizes) compared to the non-ADHD group, whereas this difference was no longer detectable at follow-up ten years later. These developmental alterations in BP from adolescence to early adulthood may reflect changes in the state of autonomic arousal, probably modulating the pathophysiology of ADHD.

Hyper-Reactivity to Salience Limits Social Interaction Among Infants Born Pre-term and Infant Siblings of Children With ASD

The ability to engage attention with selected stimuli is essential for infants to explore the world and process information relating to their surroundings. There are two main populations with a higher risk to develop attentional and social deficits whose deficits may arise from difficulties in regulating attention to salient cues: (1) siblings of children diagnosed with Autism; and (2) infants who were born pre-term. This study investigated infants' (N = 97) attention-engagement and pupil-dilation (PD) at 9 months of age, using a gaze-contingent paradigm and a structured social interaction. Specifically, we explored attention to stimuli with simple salient features (e.g., clear defined shapes, colors, and motions) vs. more complex non-social cues (amorphous shapes, colors, and motions) and social interaction in typically developing infants (TD, N = 25) and among two groups of infants at-risk to develop social difficulties (pre-terms, N = 56; siblings of children with Autism, N = 16). Findings show that the two risk groups preferred stimuli with simple features (F = 11.306, p < 0.001), accompanied by increased PD (F = 6.6, p < 0.001). Specifically, pre-term infants showed increased PD toward simple vs. complex stimuli (p < 0.001), while siblings showed a pervasive hyper-arousal to both simple and complex stimuli. Infants in the TD group preferred complex stimuli with no change in PD. Finally, the preference for the simple stimulus mediated the relationship between increased risk for social difficulties and decreased engagement duration in face-to-face interaction with the experimenter. Results suggest that activation of the attention-salience network shapes social abilities at infancy. Further, hyper-reactivity to salient stimuli limits social interaction among infants born pre-term and siblings of children with ASD.

Altered Extended Locus Coeruleus and Ventral Tegmental Area Networks in Boys with Autism Spectrum Disorders: A Resting-State Functional Connectivity Study

INTRODUCTION

Previous studies have suggested that cerebral projections of the norepinephrine (NE) and dopamine (DA) systems have important etiology and treatment implications for autism spectrum disorder (ASD).

METHODS

We used functional magnetic resonance imaging to evaluate spontaneous resting state functional connectivity in boys aged 7-15 years with ASD (n=86) and age-, intelligence quotient-matched typically developing boys (TD, n=118). Specifically, we investigated functional connectivity of the locus coeruleus (LC) and ventral tegmental area (VTA), the main source projection of neurotransmitters NE and DA, respectively.

RESULTS

1) Both the LC and VTA showed reduced connectivity with the postcentral gyrus (PoCG) in boys with ASD, reflecting the potential roles of NE and DA in modulating the function of the somatosensory cortex in boys with ASD. 2) The VTA had increased connectivity with bilateral thalamus in ASD; this alteration was correlated with repetitive and restrictive features. 3) Altered functional connectivity of both the LC and VTA with brain regions such as the angular gyrus (AG), middle temporal gyrus visual area (MT/V5), and occipital face area (OFA) in ASD group.

DISCUSSION

Our findings implicate the role of LC-NE and VTA-DA systems from the perspective of functional neuroimaging and may shed light on pharmacological studies targeting NE and DA for the treatment of autism in the future.

Atypical Development of Attentional Control Associates with Later Adaptive Functioning, Autism and ADHD Traits

Autism is frequently associated with difficulties with top-down attentional control, which impact on individuals’ mental health and quality of life. The developmental processes involved in these attentional difficulties are not well understood. Using a data-driven approach, 2 samples (N = 294 and 412) of infants at elevated and typical likelihood of autism were grouped according to profiles of parent report of attention at 10, 15 and 25 months. In contrast to the normative profile of increases in attentional control scores between infancy and toddlerhood, a minority (7–9%) showed plateauing attentional control scores between 10 and 25 months. Consistent with pre-registered hypotheses, plateaued growth of attentional control was associated with elevated autism and ADHD traits, and lower adaptive functioning at age 3 years.

Atypical alert state control in adult patients with ADHD: A pupillometry study

Although behavioral studies have repeatedly demonstrated that individuals with attention-deficit/hyperactivity disorder (ADHD) have deficits in alertness, little is known about its underlying neural basis. It is hypothesized that pupil diameter reflects the firing of norepinephrine (NE) neurons in the locus coeruleus (LC), and that the LC-NE neuromodulatory system for regulating alertness may be dysfunctional in ADHD. To clinically and non-invasively examine this hypothesis, we monitored the kinetics of pupil diameter in response to stimuli and compared them between adults with ADHD (n = 17) and typically developing (TD) adults (n = 23) during an auditory continuous performance task. Individuals in the ADHD group exhibited a significantly larger tonic pupil diameter, and a suppressed stimulus-evoked phasic pupil dilation, compared to those in the TD group. These findings provide support for the idea that the aberrant regulatory control of pupil diameter in adults with ADHD may be consistent with a compromised state of alertness resulting from a hyperactivated LC-NE system.

Pupil dilation during orienting of attention and conscious detection of visual targets in patients with left spatial neglect

Right Brain-Damaged patients (RBD) with left spatial neglect (N+), are characterised by deficits in orienting and re-orienting attention to stimuli in the contralesional left side of space. In a recent ERPs study with visual stimuli (Lasaponara et al., 2018) we have pointed out that the pathological attentional bias of N+ is matched with exaggerated novelty reaction and contextual updating of targets in the right ipsilesional space and reduced novelty reaction and contextual updating of targets in the left contralesional space. To characterise further the attentional performance of N+, here we measured Pupil Dilation (PDil), which is a reliable marker of noradrenergic-locus coeruleus activity and response to unexpected events/rewards. Compared to Neutral and Valid targets, N+ patients displayed a pathological reduction of PDil in response to infrequent Invalid targets in the left side of space, while in Healthy Controls (HC) and RBD without neglect (N-) the same targets enhanced PDil with respect to Neutral and frequent Valid targets. Invalid targets in the right side of space enhanced PDil in all experimental groups. Interestingly, both N- and N+ showed a consistent number of target omissions both in the left and right side of space. With respect to seen targets, N- showed reduced PDil in response to unseen targets both in the left and right side of space. In contrast, N+ had reduced PDil in response to unseen targets in the left side of space though not in the right side, where seen and unseen targets evoked comparable levels of PDil. These results disclose, for the first time, the PDil correlates of spatial attention in left spatial neglect and suggest that the pathological attentional bias suffered by N+ might enhance the autonomic responses reflected in PDil to unseen ipsilesional stimuli. This enhancement can contribute to biasing contextual updating and predictive coding of stimuli in the ipsilesional space, thus worsening the pathological attentional bias of N+.

Disrupted alertness and related functional connectivity in patients with focal impaired awareness seizures in temporal lobe epilepsy

OBJECTIVE

Focal impaired awareness seizures are common in temporal lobe epilepsy (TLE). The cognitive impairment associated with this type of seizure is unclear. Alertness is a fundamental aspect of cognition. The locus coeruleus (LC) is closely related to alertness. We aimed to assess the impairment in alertness and LC-related alertness network in patients with focal impaired awareness seizures.

METHODS

Patients with unilateral TLE were grouped into the only focal impaired awareness seizure group (focal group, n = 19) and the focal impaired awareness seizure with focal to bilateral tonic-clonic seizure (FBTCS) group (FBTCS group, n = 19) and compared with matched healthy controls (HC, n = 19). Alertness was assessed with the attention network test. Functional magnetic resonance imaging (fMRI) was used to construct an alertness-related LC-based functional connectivity (FC) network.

RESULTS

The focal group exhibited impaired tonic and phasic alertness and exhibited a decreased trend of LC-based FC to the left superior frontal gyrus (SFG). The FBTCS group exhibited impaired tonic alertness, phasic alertness, and alertness efficiency. No significant difference or trend in LC-based FC was found in the FBTCS group.

SIGNIFICANCE

This study reveals disrupted alertness and alertness-related LC-based FC in patients with focal impaired awareness seizures. Our results further demonstrate that the patterns of impaired alertness and of changed LC-based FC were not significantly different between focal impaired awareness seizures and FBTCS.

Autism spectrum disorder and pupillometry: A systematic review and meta-analysis

Pupillometry, measuring pupil size and reactivity, has been proposed as a measure of autonomic nervous system functioning, the latter which might be altered in individuals with autism spectrum disorder (ASD). This study aims to evaluate if pupillary responses differ in individuals with and without ASD. After performing a systematic literature search, we conducted a meta-analysis and constructed a qualitative synthesis. The meta-analysis shows a longer latency of the pupil response in the ASD-group as a substantial group difference, with a Hedges' g of 1.03 (95% CI 0.49-1.56, p = 0.008). Evidence on baseline pupil size and amplitude change is conflicting. We used the framework method to perform a qualitative evaluation of these differences. Explanations for the group differences vary between studies and are inconclusive, but many authors point to involvement of the autonomous nervous system and more specifically the locus coeruleus-norepinephrine system. Pupillometry reveals differences between people with and without ASD, but the exact meaning of these differences remains unknown. Future studies should align research designs and investigate a possible effect of maturation.

Resting and Functional Pupil Response Metrics Indicate Features of Reward Sensitivity and ASD in Children

The current study examined the relationship between quantitative measures of reward and punishment sensitivity, features of autism spectrum disorder (ASD), and resting and functional pupil response metrics across a clinically heterogeneous sample. Scores on a parent-report measure of punishment and reward sensitivity were correlated with ASD features. We also assessed whether pupil measurements could be used as a physiologic correlate of reward sensitivity and predictor of ASD diagnosis. In a logistic regression model, pupil dilation metrics, sex, and IQ, correctly classified 86.3% of participants as having an ASD diagnosis versus not. This research highlights individual differences of reward sensitivity associated with ASD features. Results support the use of pupil metrics and other patient-level variables as predictors of ASD diagnostic status.

Binding of Dopamine D1 Receptor and Noradrenaline Transporter in Individuals with Autism Spectrum Disorder: A PET Study

Although previous studies have suggested the involvement of dopamine (DA) and noradrenaline (NA) neurotransmissions in the autism spectrum disorder (ASD) pathophysiology, few studies have examined these neurotransmissions in individuals with ASD in vivo. Here, we investigated DA D1 receptor (D1R) and noradrenaline transporter (NAT) binding in adults with ASD (n = 18) and neurotypical controls (n = 20) by utilizing two different PET radioligands, [11C]SCH23390 and (S,S)-[18F]FMeNER-D2, respectively. We found no significant group differences in DA D1R (striatum, anterior cingulate cortex, and temporal cortex) or NAT (thalamus and pons) binding. However, in the ASD group, there were significant negative correlations between DA D1R binding (striatum, anterior cingulate cortex and temporal cortex) and the “attention to detail” subscale score of the Autism Spectrum Quotient. Further, there was a significant positive correlation between DA D1R binding (temporal cortex) and emotion perception ability assessed by the neurocognitive battery. Associations of NAT binding with empathic abilities and executive function were found in controls, but were absent in the ASD group. Although a lack of significant group differences in binding might be partly due to the heterogeneity of ASD, our results indicate that central DA and NA function might play certain roles in the clinical characteristics of ASD.