Atypical hemispheric specialization for faces in infants at risk for autism spectrum disorder

Among the many experimental findings that tend to distinguish those with and without autism spectrum disorder (ASD) are face processing deficits, reduced hemispheric specialization, and atypical neurostructural and functional connectivity. To investigate the earliest manifestations of these features, we examined lateralization of event-related gamma-band coherence to faces during the first year of life in infants at high risk for autism (HRA; defined as having an older sibling with ASD) who were compared with low-risk comparison (LRC) infants, defined as having no family history of ASD. Participants included 49 HRA and 46 LRC infants who contributed a total of 127 data sets at 6 and 12 months. Electroencephalography was recorded while infants viewed images of familiar/unfamiliar faces. Event-related gamma-band (30-50 Hz) phase coherence between anterior-posterior electrode pairs for left and right hemispheres was computed. Developmental trajectories for lateralization of intra-hemispheric coherence were significantly different in HRA and LRC infants: by 12 months, HRA infants showed significantly greater leftward lateralization compared with LRC infants who showed rightward lateralization. Preliminary results indicate that infants who later met criteria for ASD were those that showed the greatest leftward lateralization. HRA infants demonstrate an aberrant pattern of leftward lateralization of intra-hemispheric coherence by the end of the first year of life, suggesting that the network specialized for face processing may develop atypically. Further, infants with the greatest leftward asymmetry at 12 months where those that later met criteria for ASD, providing support to the growing body of evidence that atypical hemispheric specialization may be an early neurobiological marker for ASD.R01 DC010290 - NIDCD NIH HHS; R01-DC010290 - NIDCD NIH HH

From early markers to neuro-developmental mechanisms of autism

A fast growing field, the study of infants at risk because of having an older sibling with autism (i.e. infant sibs) aims to identify the earliest signs of this disorder, which would allow for earlier diagnosis and intervention. More importantly, we argue, these studies offer the opportunity to validate existing neuro-developmental models of autism against experimental evidence. Although autism is mainly seen as a disorder of social interaction and communication, emerging early markers do not exclusively reflect impairments of the “social brain”. Evidence for atypical development of sensory and attentional systems highlight the need to move away from localized deficits to models suggesting brain-wide involvement in autism pathology. We discuss the implications infant sibs findings have for future work into the biology of autism and the development of interventions

An Examination of the Factors that Dictate the Relative Weighting of Feedback and Feedforward Input for Speech Motor Control

Speech is arguably the most important form of human communication. Fluent speech production relies on auditory feedback for the planning, execution, and monitoring of speech movements. Auditory feedback is particularly important during the acquisition of speech, however, it has been suggested that over time speakers rely less on auditory feedback as they develop robust sensorimotor representations that allow speech motor commands to be executed in a feedforward manner. The studies reported in this thesis recorded speaker’s vocal and neural responses to altered auditory feedback in order to explore the factors that dictate the relative importance of auditory feedback for speech motor control. More specifically, studies 1 through 3 examined how the role of auditory feedback changes throughout development, while studies 4 and 5 examined the relationship between vocal variability and auditory feedback control, and lastly study 6 looked at how the predictability of auditory feedback errors influences the role of auditory feedback for speech motor control. Results of the first study demonstrated that toddlers use auditory feedback to regulate their speech motor commands, supporting the long held notion that auditory feedback is important during the acquisition of speech. While mapping out the developmental trajectory of vocal and event related potential responses to altered auditory feedback, the second study demonstrated that vocal variability, rather than age, best predicts responses to altered auditory feedback. Importantly, this suggests that the maturation of the speech motor control system is not strictly dependent on age. The third study in this thesis demonstrated that children and adults show similar rates of sensorimotor adaptation, suggesting that once speech is acquired, speakers are proficient at using sensory information to modify the planning of future speech motor commands. However, since adults produced larger compensatory responses, these results also suggested that adults are more proficient at comparing incoming auditory feedback with the feedback predicted by their sensorimotor representations, as a result of possessing more precisely mapped sensorimotor representations. The results of studies four and five demonstrated that vocal variability can be used to predict the size of compensatory responses and sensorimotor adaptation to changes in one’s auditory feedback, respectively. Furthermore, these studies demonstrated that increased variability was related to increased auditory feedback control of speech. Finally, the sixth study in this thesis demonstrated that experimentally induced predictability and variability can be used to induce increases in feedforward and auditory feedback control, respectively. In conclusion, the results reported in this thesis demonstrate that age and vocal variability, both naturally occurring and experimentally induced, are important determinants of the role of auditory feedback in speech motor control

An emergentist perspective on the origin of number sense

open2noopenZorzi, Marco; Testolin, AlbertoZorzi, Marco; Testolin, Albert

Neural correlates of action perception

When observing others we usually do not require a verbal explanation to understand what they are doing and, in many cases, why they are doing it. Specific brain regions are involved in the processing of observed actions and some of them belong to the motor system, which is mainly involved in the planning and production of movements. Intensive research of these regions suggests, that the same neurons are active during action observation and execution. It has been proposed that these neurons, so called mirror neurons, allow the simulation of observed actions in a person’s motor system. This simulation may help to understand the actions of others. This theory of motor simulation is an intriguing way to explain certain aspects of action perception, as learning by observation, but many questions remain, some of which have been addressed in this thesis

Disengagement of visual attention in infancy is associated with emerging autism in toddlerhood

Background: Early emerging characteristics of visual orienting have been associated with a wide range of typical and atypical developmental outcomes. In the current study, we examined the development of visual disengagement in infants at risk for autism. Methods: We measured the efficiency of disengaging from a central visual stimulus to orient to a peripheral one in a cohort of 104 infants with and without familial risk for autism by virtue of having an older sibling with autism. Results: At 7 months of age, disengagement was not robustly associated with later diagnostic outcomes. However, by 14 months, longer latencies to disengage in the subset of the risk group later diagnosed with autism was observed relative to other infants at risk and the low-risk control group. Moreover, between 7 months and 14 months, infants who were later diagnosed with autism at 36 months showed no consistent increases in the speed and flexibility of visual orienting. However, the latter developmental effect also characterized those infants who exhibited some form of developmental concerns (but not meeting criteria for autism) at 36 months. Conclusions: Infants who develop autism or other developmental concerns show atypicality in the development of visual attention skills from the first year of life

Measuring the Plasticity of Social Approach: A Randomized Controlled Trial of the Effects of the PEERS Intervention on EEG Asymmetry in Adolescents with Autism Spectrum Disorders

This study examined whether the Program for the Education and Enrichment of Relational Skills (PEERS: Social skills for teenagers with developmental and autism spectrum disorders: The PEERS treatment manual, Routledge, New York, 2010a) affected neural function, via EEG asymmetry, in a randomized controlled trial of adolescents with Autism spectrum disorders (ASD) and a group of typically developing adolescents. Adolescents with ASD in PEERS shifted from right-hemisphere gamma-band EEG asymmetry before PEERS to left-hemisphere EEG asymmetry after PEERS, versus a waitlist ASD group. Left-hemisphere EEG asymmetry was associated with more social contacts and knowledge, and fewer symptoms of autism. Adolescents with ASD in PEERS no longer differed from typically developing adolescents in left-dominant EEG asymmetry at post-test. These findings are discussed via the Modifier Model of Autism (Mundy et al. in Res Pract Persons Severe Disabl 32(2):124, 2007), with emphasis on remediating isolation/withdrawal in ASD

Knowing who likes who: The early developmental basis of coalition understanding

Group biases based on broad category membership appear early in human development. However, like many other primates humans inhabit social worlds also characterised by small groups of social coalitions which are not demarcated by visible signs or social markers. A critical cognitive challenge for a young child is thus how to extract information concerning coalition structure when coalitions are dynamic and may lack stable and outwardly visible cues to membership. Therefore, the ability to decode behavioural cues of affiliations present in everyday social interactions between individuals would have conferred powerful selective advantages during our evolution. This would suggest that such an ability may emerge early in life, however, little research has investigated the developmental origins of such processing. The present paper will review recent empirical research which indicates that in the first 2 years of life infants achieve a host of social-cognitive abilities that make them well adapted to processing coalition-affiliations of others. We suggest that such an approach can be applied to better understand the origins of intergroup attitudes and biases. Copyright © 2010 John Wiley & Sons, Ltd