Associations between rapid auditory processing of speech sounds and specific verbal communication skills in autism.

Introduction: The ability to rapidly process speech sounds is integral not only for processing other's speech, but also for auditory processing of one's own speech, which allows for maintenance of speech accuracy. Deficits in rapid auditory processing have been demonstrated in autistic individuals, particularly those with language impairment. We examined rapid auditory processing for speech sounds in relation to performance on a battery of verbal communication measures to determine which aspects of verbal communication were associated with cortical auditory processing in a sample of individuals with autism. Methods: Participants were 57 children and adolescents (40 male and 17 female) ages 5-18 who were diagnosed with an Autism Spectrum Disorder (ASD). Rapid auditory processing of speech sounds was measured via a magnetoencephalographic (MEG) index of the quality of the auditory evoked response to the second of two differing speech sounds ("Ga" / "Da") presented in rapid succession. Verbal communication abilities were assessed on standardized clinical measures of overall expressive and receptive language, vocabulary, articulation, and phonological processing. Associations between cortical measures of left- and right-hemisphere rapid auditory processing and verbal communication measures were examined. Results: Rapid auditory processing of speech sounds was significantly associated with speech articulation bilaterally (r = 0.463, p = 0.001 for left hemisphere and r = 0.328, p = 0.020 for right hemisphere). In addition, rapid auditory processing in the left hemisphere was significantly associated with overall expressive language abilities (r = 0.354, p = 0.013); expressive (r = 0.384, p = 0.005) vocabulary; and phonological memory (r = 0.325, p = 0.024). Phonological memory was found to mediate the relationship between rapid cortical processing and receptive language. Discussion: These results demonstrate that impaired rapid auditory processing for speech sounds is associated with dysfunction in verbal communication in ASD. The data also indicate that intact rapid auditory processing may be necessary for even basic communication skills that support speech production, such as phonological memory and articulatory control.

Linked OXTR Variants Are Associated with Social Behavior Differences in Bonobos (Pan paniscus).

Single-nucleotide polymorphisms (SNPs) in forkhead box protein P2 (FOXP2) and oxytocin receptor (OXTR) genes have been associated with linguistic and social development in humans, as well as to symptom severity in autism spectrum disorder (ASD). Studying biobehavioral mechanisms in the species most closely related to humans can provide insights into the origins of human communication, and the impact of genetic variation on complex behavioral phenotypes. Here, we aimed to determine if bonobos (Pan paniscus) exhibit individual variation in FOXP2 and OXTR loci that have been associated with human social development and behavior. Although the ASD-related variants were reported in 13-41% of the human population, we did not find variation at these loci in our sample of 13 bonobos. However, we did identify a novel variant in bonobo FOXP2, as well as four novel variants in bonobo OXTR that were 17-184 base pairs from the human ASD variants. We also found the same linked, homozygous allelic combination across the 4 novel OXTR SNPs (homozygous TGTC) in 6 of the 13 bonobos, indicating that this combination may be under positive selection. When comparing the combined OXTR genotypes, we found significant group differences in social behavior; bonobos with zero copies of the TGTC combination were less social than bonobos with one copy of the TGTC combination. Taken together, our findings suggest that these OXTR variants may influence individual-level social behavior in bonobos and support the notion that linked genetic variants are promising risk factors for social communication deficits in humans.

Changes in Frontoparietotemporal Connectivity following Do-As-I-Do Imitation Training in Chimpanzees ( Pan troglodytes).

Human imitation is supported by an underlying "mirror system" principally composed of inferior frontal, inferior parietal, and superior temporal cortical regions. Across primate species, differences in frontoparietotemporal connectivity have been hypothesized to explain phylogenetic variation in imitative abilities. However, if and to what extent these regions are involved in imitation in nonhuman primates is unknown. We hypothesized that "Do As I Do" (DAID) imitation training would enhance white matter integrity within and between frontoparietotemporal regions. To this end, four captive chimpanzees ( Pan troglodytes) were trained to reproduce 23 demonstrated actions, and four age-/sex-matched controls were trained to produce basic husbandry behaviors in response to manual cues. Diffusion tensor images were acquired before and after 600 min of training over an average of 112 days. Bilateral and asymmetrical changes in frontoparietotemporal white matter integrity were compared between DAID trained subjects and controls. We found that imitation trained subjects exhibited leftward shifts in both mean fractional anisotropy and tract strength asymmetry measures in brain regions within the mirror system. This is the first report of training-induced changes in white matter integrity in chimpanzees and suggests that frontoparietotemporal connectivity, particularly in the left hemisphere, may have facilitated the emergence of increasingly complex imitation learning abilities.