Electrophysiological Processing of Single Words in Toddlers and School-Age

1
Electrophysiological Processing of
Single Words in Toddlers and School-Age Children
with Autism Spectrum Disorder Sharon
Coffey-Corina1, Denise Padden2, Patricia K. Kuhl2
Geraldine Dawson3 Center for Mind and Brain,
University of California, Davis I-LABS2,
University of Washington UW Autism Center3,
Seattle, Washington
Typically Developing
Autism Spectrum Disorder
Introduction 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.

• 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 (N24) and 9-10 year olds (N27) with
  Autism Spectrum Disorder.
• Typically developing age matched controls
  (N40).
• 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 dBA.
• Procedure
• Toddlers sat on their parents lap watching an
  experimenter entertain 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.

Results - Toddlers (19-30 months old) Known and
Unknown words 100-200 msec. 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 P2-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 P2 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.

• Discussion
• Toddlers with more severe autism symptoms
  process words differently 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 P1 over the right hemisphere for
  nonsense as to compared to known words. King and
  Kutas (1995) found larger P2s 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 P2 (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 500-700 ms
  when the LF group exhibits differential
  processing for unknown words as compared to TD
  and HF.

Solid lines Known words,
Dotted lines Unknown words Negative
is plotted UP. Calibration bar is 3 microvolts
 
 
Typically Developing
Autism Spectrum Disorder
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 53,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 168,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, F9-F20.
Acknowledgements The authors would like to thank
David P. Corina for his contributions to this
poster. This research was funded by grants from
NIH (U19HD34565) and NIMH (U54MH066399).
Contact information Sharon Coffey-Corina
sccorina_at_ucdavis.edu Patricia K. Kuhl
pkkuhl_at_u.washington.edu
Low Functioning ASD 9-10 yrs (N10)
Typical 9-10 yr olds (N 20)
High Functioning ASD 9-10 yrs (N17)