Lateralization of ERPs to speech and handedness in the early development of Autism Spectrum Disorder.
BACKGROUND
Language is a highly lateralized function, with typically developing individuals showing left hemispheric specialization. Individuals with autism spectrum disorder (ASD) often show reduced or reversed hemispheric lateralization in response to language. However, it is unclear when this difference emerges and whether or not it can serve as an early ASD biomarker. Additionally, atypical language lateralization is not specific to ASD as it is also seen more frequently in individuals with mixed- and left-handedness. Here, we examined early asymmetry patterns measured through neural responses to speech sounds at 12 months and behavioral observations of handedness at 36 months in children with and without ASD.


METHODS
Three different groups of children participated in the study: low-risk controls (LRC), high risk for ASD (HRA; infants with older sibling with ASD) without ASD, and HRA infants who later receive a diagnosis of ASD (ASD). Event-related potentials (ERPs) to speech sounds were recorded at 12 months. Utilizing a novel observational approach, handedness was measured by hand preference on a variety of behaviors at 36 months.


RESULTS
At 12 months, lateralization patterns of ERPs to speech stimuli differed across the groups with the ASD group showing reversed lateralization compared to the LRC group. At 36 months, factor analysis of behavioral observations of hand preferences indicated a one-factor model with medium to high factor loadings. A composite handedness score was derived; no group differences were observed. There was no association between lateralization to speech at 12 months and handedness at 36 months in the LRC and HRA groups. However, children with ASD did show an association such that infants with lateralization patterns more similar to the LRC group at 12 months were stronger right-handers at 36 months.


CONCLUSIONS
These results highlight early developmental patterns that might be specific to ASD, including a potential early biomarker of reversed lateralization to speech stimuli at 12 months, and a relation between behavioral and neural asymmetries. Future investigations of early asymmetry patterns, especially atypical hemispheric specialization, may be informative in the early identification of ASD.
Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA 02215 USA.
Kayla H
KH
Finch
New York University School of Medicine/Bellevue Hospital Center, 462 First Avenue, New York, NY 10016 USA.
Anne M
AM
Seery
MIND Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817 USA.
Meagan R
MR
Talbott
Laboratories of Cognitive Neuroscience, Division of Developmental Medicine, Boston Children's Hospital, 1 Autumn Street, Boston, MA 02215 USA.|Harvard Medical School, 25 Shattuck Street, Boston, MA 02215 USA.|Harvard Graduate School of Education, 13 Appian Way, Cambridge, MA 02138 USA.
Charles A
CA
Nelson
Department of Psychological and Brain Sciences, Boston University, 64 Cummington Mall, Boston, MA 02215 USA.
Helen
H
Tager-Flusberg
Autism spectrum disorders; Event-related potentials; Handedness; Lateralization; Speech processing