Learning with individual-interest outcomes in Autism Spectrum Disorder.

Recent work has suggested atypical neural reward responses in individuals with Autism Spectrum Disorder (ASD), particularly for social reinforcers. Less is known about neural responses to restricted interests and few studies have investigated response to rewards in a learning context. We investigated neurophysiological differences in reinforcement learning between adolescents with ASD and typically developing (TD) adolescents (27 ASD, 31 TD). FMRI was acquired during a learning task in which participants chose one of two doors to reveal an image outcome. Doors differed in their probability of showing liked and not-liked images, which were individualized for each participant. Participants chose the door paired with liked images, but not the door paired with not-liked images, significantly above chance and choice allocation did not differ between groups. Interestingly, participants with ASD made choices less consistent with their initial door preferences. We found a neural prediction-error response at the time of outcome in the ventromedial prefrontal and posterior cingulate cortices that did not differ between groups. Together, behavioural and neural findings suggest that learning with individual interest outcomes is not different between individuals with and without ASD, adding to our understanding of motivational aspects of ASD.

Girls' attentive traits associate with cerebellar to dorsal attention and default mode network connectivity.

Attention traits are a cornerstone to the healthy development of children's performance in the classroom, their interactions with peers, and in predicting future success and problems. The cerebellum is increasingly appreciated as a region involved in complex cognition and behavior, and moreover makes important connections to key brain networks known to support attention: the dorsal attention and default mode networks (DAN; DMN). The cerebellum has also been implicated in childhood disorders affecting attention, namely autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), suggesting that attention networks extending to the cerebellum may be important to consider in relation to attentive traits. Yet, direct investigations into the association between cerebellar FC and attentive traits are lacking. Therefore, in this study we examined attentive traits, assessed using parent reports of ADHD and ASD symptoms, in a community sample of 52 girls aged 4-7 years, i.e. around the time of school entry, and their association with cerebellar connections with the DAN and DMN. We found that cortico-cerebellar functional connectivity (FC) jointly and differentially correlated with attentive traits, through a combination of weaker and stronger FC across anterior and posterior DAN and DMN nodes. These findings suggest that cortico-cerebellar integration may play an important role in the manifestation of attentive traits.

Reduced White Matter Fiber Density in Autism Spectrum Disorder.

Differences in brain networks and underlying white matter abnormalities have been suggested to underlie symptoms of autism spectrum disorder (ASD). However, robustly characterizing microstructural white matter differences has been challenging. In the present study, we applied an analytic technique that calculates structural metrics specific to differently-oriented fiber bundles within a voxel, termed "fixels". Fixel-based analyses were used to compare diffusion-weighted magnetic resonance imaging data from 25 individuals with ASD (mean age = 16.8 years) and 27 typically developing age-matched controls (mean age = 16.9 years). Group comparisons of fiber density (FD) and bundle morphology were run on a fixel-wise, tract-wise, and global white matter (GWM) basis. We found that individuals with ASD had reduced FD, suggestive of decreased axonal count, in several major white matter tracts, including the corpus callosum (CC), bilateral inferior frontal-occipital fasciculus, right arcuate fasciculus, and right uncinate fasciculus, as well as a GWM reduction. Secondary analyses assessed associations with social impairment in participants with ASD, and showed that lower FD in the splenium of the CC was associated with greater social impairment. Our findings suggest that reduced FD could be the primary microstructural white matter abnormality in ASD.

Largely Typical Electrophysiological Affective Responses to Special Interest Stimuli in Adolescents with Autism Spectrum Disorder.

Circumscribed interests are a symptom of autism spectrum disorder (ASD) that may be related to exaggerated affective neural responses. However, the use of generic ASD-interest image stimuli has left an open question as to whether affective responses towards individual interests are greater in ASD compared to typically developing (TD) controls. We compared amplitudes of the late positive potential (LPP), an affective electroencephalographic response, between adolescents with ASD (N = 19) and TD adolescents (N = 20), using images tailored to individual likes and dislikes. We found an LPP response for liked and disliked images, relative to neutral, with no difference in amplitude between groups. This suggests that the LPP is not atypical in adolescents with ASD towards images of individual interests.

Reinforcement Learning in Autism Spectrum Disorder.

Early behavioral interventions are recognized as integral to standard care in autism spectrum disorder (ASD), and often focus on reinforcing desired behaviors (e.g., eye contact) and reducing the presence of atypical behaviors (e.g., echoing others' phrases). However, efficacy of these programs is mixed. Reinforcement learning relies on neurocircuitry that has been reported to be atypical in ASD: prefrontal-sub-cortical circuits, amygdala, brainstem, and cerebellum. Thus, early behavioral interventions rely on neurocircuitry that may function atypically in at least a subset of individuals with ASD. Recent work has investigated physiological, behavioral, and neural responses to reinforcers to uncover differences in motivation and learning in ASD. We will synthesize this work to identify promising avenues for future research that ultimately can be used to enhance the efficacy of early intervention.

Circumscribed interests in adolescents with Autism Spectrum Disorder: A look beyond trains, planes, and clocks.

Adolescence is a unique developmental period, characterized by physical and emotional growth and significant maturation of cognitive and social skills. For individuals with Autism Spectrum Disorder (ASD), it is also a vulnerable period as cognitive and social skills can deteriorate. Circumscribed interests (CIs), idiosyncratic areas of intense interest and focus, are a core symptom of ASD that may be associated with social development. Yet, relatively little is known about the expression of CIs in adolescents with ASD. Many studies investigating CIs have used images depicting items of special interest; however, it is not clear how images should be customized for adolescent studies. The goal of this study was to gain insight into the types of images that may be appropriate for studies of CIs in adolescents with ASD. To this end, we used a mixed methods design that included, 1) one-on-one interviews with 10 adolescents (4 with ASD and 6 TD), to identify categories of images that were High Autism Interest ('HAI') or High Typically Developing Interest ('HTD'), and 2) an online survey taken by fifty-three adolescents with ASD (42 male) and 135 typically developing (TD) adolescents (55 male) who rated how much they liked 105 'HAI' and 'HTD' images. Although we found a significant interaction between 'HAI' and 'HTD' categories and diagnosis, neither group significantly preferred one category over the other, and only one individual category ('Celebrities') showed a significant group effect, favored by TD adolescents. Males significantly preferred 'HAI' images relative to females, and TD adolescents significantly preferred images with social content relative to adolescents with ASD. Our findings suggest that studies investigating affective or neural responses to CI-related stimuli in adolescents should consider that stereotypical ASD interests (e.g. trains, gadgets) may not accurately represent individual adolescents with ASD, many of whom show interests that overlap with TD adolescents (e.g. video games).

Morphological Alterations in the Thalamus, Striatum, and Pallidum in Autism Spectrum Disorder.

Autism spectrum disorder (ASD) is a common neurodevelopmental disorder with cognitive, motor, and emotional symptoms. The thalamus and basal ganglia form circuits with the cortex supporting all three of these behavioral domains. Abnormalities in the structure of subcortical regions may suggest atypical development of these networks, with implications for understanding the neural basis of ASD symptoms. Findings from previous volumetric studies have been inconsistent. Here, using advanced surface-based methodology, we investigated localized differences in shape and surface area in the basal ganglia and thalamus in ASD, using T1-weighted anatomical images from the Autism Brain Imaging Data Exchange (373 male participants aged 7-35 years with ASD and 384 typically developing). We modeled effects of diagnosis, age, and their interaction on volume, shape, and surface area. In participants with ASD, we found expanded surface area in the right posterior thalamus corresponding to the pulvinar nucleus, and a more concave shape in the left mediodorsal nucleus. The shape of both caudal putamen and pallidum showed a relatively steeper increase in concavity with age in ASD. Within ASD participants, restricted, repetitive behaviors were positively associated with surface area in bilateral globus pallidus. We found no differences in overall volume, suggesting that surface-based approaches have greater sensitivity to detect localized differences in subcortical structure. This work adds to a growing body of literature implicating corticobasal ganglia-thalamic circuits in the pathophysiology of ASD. These circuits subserve a range of cognitive, emotional, and motor functions, and may have a broad role in the complex symptom profile in ASD.

Social eye gaze modulates processing of speech and co-speech gesture.

In human face-to-face communication, language comprehension is a multi-modal, situated activity. However, little is known about how we combine information from different modalities during comprehension, and how perceived communicative intentions, often signaled through visual signals, influence this process. We explored this question by simulating a multi-party communication context in which a speaker alternated her gaze between two recipients. Participants viewed speech-only or speech+gesture object-related messages when being addressed (direct gaze) or unaddressed (gaze averted to other participant). They were then asked to choose which of two object images matched the speaker's preceding message. Unaddressed recipients responded significantly more slowly than addressees for speech-only utterances. However, perceiving the same speech accompanied by gestures sped unaddressed recipients up to a level identical to that of addressees. That is, when unaddressed recipients' speech processing suffers, gestures can enhance the comprehension of a speaker's message. We discuss our findings with respect to two hypotheses attempting to account for how social eye gaze may modulate multi-modal language comprehension.

An online database of infant functional near infrared spectroscopy studies: a community-augmented systematic review.

Until recently, imaging the infant brain was very challenging. Functional Near InfraRed Spectroscopy (fNIRS) is a promising, relatively novel technique, whose use is rapidly expanding. As an emergent field, it is particularly important to share methodological knowledge to ensure replicable and robust results. In this paper, we present a community-augmented database which will facilitate precisely this exchange. We tabulated articles and theses reporting empirical fNIRS research carried out on infants below three years of age along several methodological variables. The resulting spreadsheet has been uploaded in a format allowing individuals to continue adding new results, and download the most recent version of the table. Thus, this database is ideal to carry out systematic reviews. We illustrate its academic utility by focusing on the factors affecting three key variables: infant attrition, the reliability of oxygenated and deoxygenated responses, and signal-to-noise ratios. We then discuss strengths and weaknesses of the DBIfNIRS, and conclude by suggesting a set of simple guidelines aimed to facilitate methodological convergence through the standardization of reports.