Electrophysiological Processing of Single Words in Toddlers and

Electrophysiological Processing of Single Words in Toddlers and School-Age Children with Autism Spectrum Disorder Sharon Coffey-Corina 1, Denise Padden 2, Patricia K. Kuhl 2 & Geraldine Dawson 3 Center for Mind and Brain, University of California, Davis; I-LABS 2, University of Washington; UW Autism Center 3, Seattle, Washington Typically Developing Autism Spectrum Disorder Results - School Age Children (9 -10 years old) Introduction Known and Unknown words: Language and communication deficits are key components of autism spectrum disorder. We examined event related potentials (ERPs) recorded during auditory presentation of known words, unknown words, and known words played backwards. Previous studies report ERP differentiation of words in typically developing (TD) children as young as 12 months of age (Mills et al. , 1993). We tested toddlers and 9 -10 year old children with autism spectrum disorder (ASD) and TD controls. Children with ASD were subdivided into high (HF) and low functioning (LF) groups. • TD subjects exhibit a significant word type effect for known and unknown words at 500700 (p =. 047) and at 600 -900 ms (p =. 027) • HF subjects exhibit the same effect, but only at 600 -900 ms (p =. 043). • LF children failed to exhibit word type effects between known and unknown words. • In addition, LF had larger P 2 in the right hemisphere (p =. 055); HF and TD showed no hemisphere differences for P 2. Backwards Words: • Backwards words were processed in a similar manner by all groups. Backwards words were more positive than both known and unknown words at all sites, consistent with previous studies of young TD children. Typically Developing 19 -30 months old ( N=20) ERP Methods ERP Recordings • Data was collected at 20 electrode sites, using the standard international 10/20 system with electro-caps. Trials were edited by hand to insure artifact free data. Participants • 2 groups of 19 -30 month old toddlers and of 9 -10 year olds. • Toddlers (N=24) and 9 -10 year olds (N=27) with Autism Spectrum Disorder. • Typically developing age matched controls (N=40). Stimuli • Ten known (K), unknown (U), and backwards (B) words were used. Each word was presented six times for a total of 180 words. • Known words. Parental reports were used to create customized lists of known words for each individual subject. Mean duration was 671 ms. • Unknown words were matched for word length and were similar in phonological form to known words. Mean duration was 744 ms. • Backwards words were reversed wave files of the known words. • Words were presented at 65 -67 d. BA. High Functioning ASD 19 -30 months (N=12) Results - Toddlers (19 -30 months old) Known and Unknown words: 100 -200 msec. Low Functioning ASD 19 -30 months (N=12) Solid lines Known words, Dotted lines Unknown words Discussion Negative is plotted UP. Calibration bar is 3 microvolts • Toddlers with more severe autism symptoms process words differently A comparison of TD, HF and LF groups reveals a significant interaction between group and hemisphere (p =. 045). This effect is driven by the LF group which exhibits a P 2 -like component in the right hemisphere. This pattern persists into the 175 -300 ms measurement window. The LF group also had a word by hemisphere by site effect (p=. 008). Unknown words had a larger P 2 than known words in the right hemisphere. 300 -500 msec. TD, HF and LF groups exhibit a significant word by hemisphere by group interaction in this measurement window (p =. 009). This effect is driven by the LF group which exhibits a significant hemisphere effect for known words, with a more negative response in the right hemisphere. Paired comparisons show significant differences between LF and TD groups, and between LF and HF groups. TD and HF groups are not significantly different. A separate analysis for unknown words did not yield significant effects. This pattern is also observed in the 170 -300 ms measurement window. 600 -900 msec. None of the 3 toddler groups had significant differences between known and unknown words in this time window. Backwards Words: Backwards words were processed in a similar manner by all groups. Backwards words were more positive than both known and unknown words at all sites, consistent with previous studies of young TD children. Typically Developing Autism Spectrum Disorder Procedure • Toddlers sat on their parent’s lap watching an experimentertain them with quiet toys or a silent video. Older children sat in a chair watching a silent video. • Measurements of waveforms were taken for mean amplitude, peak latency and amplitude at 100 -200, 170 -300, 300 -500, 500 -700 and 600 -900 ms for all 3 word types in both groups at all sites in both hemispheres. Acknowledgements: The authors would like to thank David P. Corina for his contributions to this poster. This research was funded by grants from NIH (U 19 HD 34565) and NIMH (U 54 MH 066399). Contact information: Sharon Coffey-Corina sccorina@ucdavis. edu Patricia K. Kuhl pkkuhl@u. washington. edu Typical 9 -10 yr olds (N= 20) High Functioning ASD 9 -10 yrs (N=17) Low Functioning ASD 9 -10 yrs (N=10) than both TD and HF toddlers as early as 100 -200 ms. It is possible that these early effects reflect low-level auditory processing effects. Our results may be related to well documented hyper- sensitivity to auditory stimuli in some children with ASD. Mills et al. (2004) reported that TD 20 month olds had a larger P 1 over the right hemisphere for nonsense as to compared to known words. King and Kutas (1995) found larger P 2’s in adults with poor sentence comprehension. • TD and HF children process known and unknown words without significant hemispheric asymmetries. Both LF toddlers and LF school age children show a larger P 2 (100 -250 ms) for unknown words in the right hemisphere. The significant hemispheric asymmetry in the LF group persists into the 300 -500 ms measurement window, where TD children tested in our laboratory begin to exhibit significant differences between known and unknown words (Coffey-Corina et al. , 2006). In the 300 -500 ms measurement window, the hemispheric asymmetry for the LF group is significant, with known words more negative in the right hemisphere. Hemispheric asymmetries are still observed in the LF group between 500700 ms when the LF group exhibits differential processing for unknown words as compared to TD and HF. References: Coffey-Corina, S. , Kuhl, P. , Padden, D. & Dawson, G. (2006) ERPs to Known, Unknown and Backwards Words in Toddlers with Autism Spectrum Disorder. Poster presentation at Cognitive Neuroscience Society, April 2006. Mills, D. , Coffey-Corina, S. & Neville, H. (1993) Language Acquisition and Cerebral Specialization in 20 month old Infants. Journal of Cognitive Neuroscience 5: 3, pp. 317 -334. King J. and Kutas M (1995). Who did what and when? Using word- and clause-level ERPS to monitor working memory. Journal of Cognitive Neuroscience. 7, 3, pp. 376 -395 Mills, D. , Prat C. , Zangl, R. , Stager, C. , Neville, H. & Werker, J. (2004) Language Experience and the Organization of Brain Activity to Phonetically Similar Words: ERP Evidence from 14 and 20 month olds. Journal of Cognitive Neuroscience 16: 8, pp, 1452 -1464. Kuhl, P. K. , Coffey-Corina, S. , Padden, D. M. , & Dawson, G. (2005). Links between social and linguistic processing of speech in preschool children with autism: Behavioral and electrophysiological measures. Developmental Science, 8, F 9 -F 20.