Oversensitivity to touch is common in autism and can lead to discomfort and harm. In some cases, people with autism avoid other people’s touch but seek out tactile stimulation through self- stimulatory behaviors. Self-stimulation can be anything from finger tapping to headbanging, which is harmful and dangerous. While the differences in the brain’s response to different types of touch have been studied in neurotypical people, there is little information on the different responses in people with autism. This fellow will examine how the autistic brain responds to different types of touch, ultimately providing a biological basis for determining why some touch is avoided while some is sought out, which could improve therapy for dangerous self-stimulatory behaviors.
Understanding Hyper-Responsiveness to Touch in the Autistic Brain
Rett Syndrome is caused by a mutation on the X chromosome at MeCP2. Girls with Rett Syndrome share many features of autism, including delayed or lack of language development, impaired fine motor skills, repetitive behaviors and cognitive disability. MeCP2 activity is also regulated by environmental factors and has been implicated in autism when a genetic cause has not been identified. This fellow will look closely at changes in MeCP2 binding and how it regulates gene expression by isolating different types of neurons at different ages to determine which are critical in the progression of symptoms. The fellow will also employ a sophisticated analysis of machine learning techniques to integrate the data to predict how MeCP2 activity regulates different neuron types at different points in development. This will allow scientists to move closer to providing patients with targeted approaches to interventions.
On the first podcast of 2024, we describe a new paper in the Journal of the American Medical Association or JAMA which uses physiological measurements like heart rate and skin conductance to predict severe and dangerous behaviors, specifically aggression. If aggression can be predicted, it might be able to be prevented. It turns out aggression can be predicted up to 3 minutes before an episode occurs, in the future these measures can be used to possibly redirect aggression. In a separate study, the issue of stigma is addressed. There is an intense debate over “person first” vs. “identity first” language in autism, promoting recommendations of using one over the other because fear that person first language promotes stigma against autism. A new study shows that there is no added prejudice or fear using either person first or identity first language, but the stigma associated with schizophrenia is worse than it is for autism. What contributes to stigma? There is a wide range of experiences and perceptions of autism that need to be addressed. It’s not as simple as the language used.
Nobody ever talks about catatonia in autism. This podcast explores the symptoms of catatonia, how to measure it, what parents should know about tracking the symptoms, what the treatments are, and what the causes are. Dr. Martine Lamy from Cincinnati Children’s Hospital explains her work looking at genetic causes in those with catatonia and neurodevelopmental disorders. It’s important to do genetic testing on all individuals who present with catatonia because this information led to better treatments in some people. Identifying a genetic cause of not just catatonia but also neurodevelopmental disorders like ASD gives families a community but also allows them to identify more targeted interventions.
https://pubmed.ncbi.nlm.nih.gov/37864080/
https://pubmed.ncbi.nlm.nih.gov/37642312/
The words “syndromic autism” have been used to describe individuals with autism who also have a rare genetic mutation. Is it time to change those words to something else? In this week’s podcast episode, cientists and clinicians Drs. Jacob Vorstman and Steve Scherer from the University of Toronto share recent data in understanding autism, the role of genetic testing in autism in predicting and treating other conditions that someone with autism may have, and why the words “syndromic autism” may need to be updated to describe a subgroup of autism.
On this week’s podcast we talk to Sergiu Pasca from Stanford University. He has revolutionized the field of understanding the field of brain development in neurodevelopmental disorders and just published a new study which examined the genetic influence of brain assembly. The way he does this is quite remarkable. His lab uses assembloids, which are many many many stem cells which form into a tiny brain. He explains what an interneuron is, why it is important for brain function, and how genetics can influence how these neurons work. This way the development of the brain from the first cell can be tracked and even manipulated to understand what happens in autism, and what therapies might be the most helpful to target these interneurons. Thank you Dr. Pasca.
Open access! https://pubmed.ncbi.nlm.nih.gov/37758944/
Everyone knows that every person with autism has their own unique strengths and challenges. Autism is heritable, and there are over 100 genes associated with autism. There are also an unknown number of environmental factors influencing outcome, so the heterogeneity is not necessarily surprising. But why would two people with the same genetic mutation have variable outcomes? Researchers led by the Institut Pasteur in France looked at the range of outcomes in people with a rare genetic mutation associated with autism, focusing on those without an autism diagnosis. This week’s podcast is an interview with the lead author of the paper, Thomas Rolland, PhD from France. The presence of the variants in those without ASD were associated with lowered cognitive ability, education level and employment status. The bottom line of these finds are that genes affect proteins which form the brain and control brain function. However, there are multiple factors that influence outcome. Some of them may be sex or gender, prenatal exposures. It’s not just one thing, there are many things influencing an autism diagnosis.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10353945/pdf/41591_2023_Article_2408.pdf
Can biomarkers that measure things like visual social attention be a good proxy for an in person behavioral diagnosis? Why would this be important? This week’s podcast explores two new studies the the Journal of the American Medical Association that show a simple device called EarliPoint can be used to shorten the wait times to receive a diagnostic evaluation. Currently autism can be diagnosed at 18 months but most families do not get into an appointment until 4-5 years of age. That can change. Families were able to easily complete it, it predicted things like not just a diagnosis but behavioral features and cognitive ability. It’s been deployed in 6 speciality centers, been approved by the FDA, and hopefully coming to a clinic near you soon.
Abstract
Fragile X messenger ribonucleoprotein 1 protein (FMRP) binds many mRNA targets in the brain. The contribution of these targets to fragile X syndrome (FXS) and related autism spectrum disorder (ASD) remains unclear. Here, we show that FMRP deficiency leads to elevated microtubule-associated protein 1B (MAP1B) in developing human and non-human primate cortical neurons. Targeted MAP1B gene activation in healthy human neurons or MAP1B gene triplication in ASD patient-derived neurons inhibit morphological and physiological maturation. Activation of Map1b in adult male mouse prefrontal cortex excitatory neurons impairs social behaviors. We show that elevated MAP1B sequesters components of autophagy and reduces autophagosome formation. Both MAP1B knockdown and autophagy activation rescue deficits of both ASD and FXS patients’ neurons and FMRP-deficient neurons in ex vivo human brain tissue. Our study demonstrates conserved FMRP regulation of MAP1B in primate neurons and establishes a causal link between MAP1B elevation and deficits of FXS and ASD.
Abstract
Social motivation is critical to the development of typical social functioning. Social motivation, specifically one or more of its components (e.g., social reward seeking or social orienting), could be relevant for understanding phenotypes related to autism. We developed a social operant conditioning task to quantify effort to access a social partner and concurrent social orienting in mice. We established that mice will work for access to a social partner, identified sex differences, and observed high test-retest reliability. We then benchmarked the method with two test-case manipulations. Shank3B mutants exhibited reduced social orienting and failed to show social reward seeking. Oxytocin receptor antagonism decreased social motivation, consistent with its role in social reward circuitry. Overall, we believe that this method provides a valuable addition to the assessment of social phenotypes in rodent models of autism and the mapping of potentially sex-specific social motivation neural circuits.
Keywords: Shank3b; autism; behavioral assay; mice; operant conditioning; oxytocin; sex differences; sociability; social motivation.
Abstract
Understanding the neural processes underpinning individual differences in early language development is of increasing interest, as it is known to vary in typical development and to be quite heterogeneous in neurodevelopmental conditions. However, few studies to date have tested whether early brain measures are indicative of the developmental trajectory of language, as opposed to language outcomes at specific ages. We combined recordings from two longitudinal studies, including typically developing infants without a family history of autism, and infants with increased likelihood of developing autism (infant-siblings) (N = 191). Electroencephalograms (EEG) were recorded at 6 months, and behavioral assessments at 6, 12, 18, 24 and 36 months of age. Using a growth curve model, we tested whether absolute EEG spectral power at 6 months was associated with concurrent language abilities, and developmental change in language between 6 and 36 months. We found evidence of an association between 6-month alpha-band power and concurrent, but not developmental change in, expressive language ability in both infant-siblings and control infants. The observed association between 6-month alpha-band power and 6-month expressive language was not moderated by group status, suggesting some continuity in neural mechanisms.
Abstract
Advancing from gene discovery in autism spectrum disorders (ASDs) to the identification of biologically relevant mechanisms remains a central challenge. Here, we perform parallel in vivo functional analysis of 10 ASD genes at the behavioral, structural, and circuit levels in zebrafish mutants, revealing both unique and overlapping effects of gene loss of function. Whole-brain mapping identifies the forebrain and cerebellum as the most significant contributors to brain size differences, while regions involved in sensory-motor control, particularly dopaminergic regions, are associated with altered baseline brain activity. Finally, we show a global increase in microglia resulting from ASD gene loss of function in select mutants, implicating neuroimmune dysfunction as a key pathway relevant to ASD biology.
Keywords: CP: Neuroscience; autism spectrum disorder; dopaminergic neurons; genetics; microglia; neurodevelopment; zebrafish.