Lateralization to Speech Stimuli and Handedness in Early Development of Autism Spectrum Disorder

Saturday, May 14, 2016: 11:30 AM-1:30 PM
Hall A (Baltimore Convention Center)
K. H. Finch1, A. Seery2, M. R. Talbott3, H. Tager-Flusberg1 and C. A. Nelson4, (1)Boston University, Boston, MA, (2)New York University School of Medicine, New York, NY, (3)University of California, Davis, Sacramento, CA, (4)Boston Children's Hospital/Harvard Medical School, Boston, MA

Numerous studies have investigated the patterns of asymmetry in individuals with autism spectrum disorder (ASD).  Atypical lateralization of language has been found in individuals at risk for ASD as young as 12-months-old.  Seery et al. (2013) found distinct patterns of lateralization in the late slow wave (LSW) in response to speech, and in follow-up studies, 12-month-olds later diagnosed with ASD showed reversed lateralization.  Atypical behavioral asymmetry has been observed as left and mixed handedness occur more frequently in children with ASD (Dane & Balci, 2007).  To date, no study has investigated the relationship between early patterns of cerebral lateralization and behavioral asymmetry in infants later diagnosed with ASD.


The current study aims to explore the relationship between neural responses to language stimuli at 12 months and handedness at 36 months. 



79 monolingual, English-speaking infants were divided into three groups: Low-risk controls (LRC; N=40), high-risk for ASD (HRA) infants (older sibling with ASD) without ASD (HRA-; N=31), and HRA infants with ASD (HRA+; N=8)

Language Lateralization

Event-related potentials to speech sounds were recorded at 12 months.  A later sustained negativity (LSW; 300-700ms) was observed over the central regions.  A laterality index was calculated by subtracting the mean amplitude of the LSW of the right hemisphere from the mean amplitude of LSW of the left hemisphere (LSWleft-LSWright). 


Utilizing a novel observational approach, hand preference was measured on a variety of behavioral observations during the Autism Diagnostic Observation Schedule and the Mullen Scales of Early Learning at 36 months.  Factor analysis with principle axis factoring extraction technique indicated a one-factor model with medium to high factor loadings (Table 1).  Using these measures, a composite handedness score ([RH-LH]/[RH+LH]*100) was calculated for each individual.


At 12 months, LSW laterality index was significantly different across groups (F(2,76)=3.86, p<.05) with LRC and HRA+ infants showing opposite patterns (p<.05); handedness scores at 36 months did not differ across groups (H(2)=3.934, p=.140) (Table 2). 

Across all participants, there was no significant relationship between LSW asymmetry at 12 months and handedness at 36 months (rs=-0.09, p=0.43). Within each of the groups, 12 month LSW asymmetry did not significantly predict 36 month handedness in LRC infants (rs=-0.22, p=0.17) or HRA- infants (rs=-0.05, p=0.78).  Conversely, for HRA+ infants, there was a significant relationship (rs=0.78, p<0.05) such that infants with a laterality index more similar to the LRC group at 12 months were stronger right handers at 36 months.


This study is the first to investigate the relationship between early asymmetry patterns in infants with and without ASD.  We did not find a relationship between language lateralization at 12 months and handedness at 36 months in children without ASD.  However, infants with ASD exhibit such a relationship in that HRA+ infants with a more typical response to speech at 12 months have more typical handedness at 36 months.  This suggests that these individuals might have an underlying protective factor in the early development of cortical lateralization which later manifests into more typical language lateralization and handedness.