Vocal language development in genetically different twins; gaze behavior in face-to-face conversation

Two studies that piqued our interest:

• Analysis of vocal language development in a pair of fraternal twins, as captured on home videos, provided an opportunity to parse genetic influences from environmental ones in a study published last month. The twins grew up in the same social-communicative environment, but their language skills diverged. One sister’s proficiency in making more complex speech sounds (articulatory complexity) increased over the first two years of life. The other, who carried a variant of the MECP2 gene, was eventually diagnosed with Rett syndrome. She babbled in an age-typical way at 7 months of age but vocalized less overall and with less variability and complexity in subsequent months. “This developmental trajectory points to very early stagnation and regression in [the latter twin], occurring earlier than typically observed,” the authors write. The Journal of Genetic Psychology
• In face-to-face encounters, autistic men are less likely than their non-autistic peers both to initiate and break eye contact, new findings suggest. In the study, which included 39 autistic men and 29 matched non-autistic participants, these group differences were larger when people were listening rather than talking. And the autism group showed more variability; one in two had gaze behavior that was similar to that of the non-autism group. Feelings of shame, but not autism traits, appeared to be linked to atypical gaze behavior. The researchers assert that their method of eye-tracking two people in conversation provides richer data than the more common method of one person watching a video. Spectrum has previously covered other novel methods that monitor subtle behaviors in social interactions. Molecular Autism

More autism research we spotted:

• “Astrocytic-supplied cholesterol drives synaptic gene expression programs in developing neurons and downstream astrocytic transcriptional programs” bioRxiv
  The Transmitter has reported on other ways that astrocytes and neurons interact.
• “Predictors of placebo response in the study of oxytocin in autism to improve reciprocal social behaviors” Journal of Child and Adolescent Psychopharmacology
  Spectrum has previously covered factors that may affect results in oxytocin trials.
• “PTEN mutations impair CSF dynamics and cortical networks by dysregulating periventricular neural progenitors” Nature Neuroscience

• “Causal differential expression analysis under unmeasured confounders with causarray” bioRxiv
• “Rapport in same and mixed neurotype groups of autistic and non-autistic adults” Autism
• “Untangling the molecular mechanisms contributing to autism spectrum disorder using stem cells” Autism Research
• “TSC1 deletion in purkinje neurons disrupts the axon initial segment, impairing excitability and cerebellar function” bioRxiv
• “Polygenic scores for autism are associated with reduced neurite density in adults and children from the general population” Molecular Psychiatry
• “China Autism Brain Imaging Consortium: Charting brain growth in Chinese children with autism” bioRxiv