| High-functioning children with autism spectrum disorders (ASD) exhibit a variable and puzzling profile of deficits and abilities in semantic processing of language. This series of three studies investigated semantic processing of speech in children with ASD. The participants were 18 high-functioning (IQ> 70) children with ASD, and 18 controls with typical development, ages 11-15, matched by age and non-verbal IQ.;In Experiment 1, participants indicated category membership of spoken words with a button press while event-related potentials (ERPs) were recorded. It was hypothesized that the children with ASD would not exhibit the N4 effect (differential neural processing of in-versus out-of --category words). Both groups showed a clear increase in waveform negativity, peaking at approximately 550 msec post-stimulus presentation, in response to both conditions. The difference between the amplitudes in each condition was significant in both groups, i.e., both produced the N4 effect. For both groups, effects were largest over centro-parietal regions.;In Experiment 2 (semantic priming) children listened to pairs of words in a lexical decision task. Relationships between words were semantic or associative. It was hypothesized that the controls would exhibit priming for all relationships, while the children with ASD would show priming effects only for associative. Both groups showed significant priming effects when a highly prototypical category exemplar primed a target that was a poor exemplar, but not vice versa. Both groups also showed robust priming effects for asymmetrically associated words. Response latency and accuracy did not differ between the groups.;In Experiment 3, children listened to sentences that ended with a word that was (1) congruous and highly expected, given the sentence context, (2) related to the most expected word ("related anomaly" effect), (3) incongruous and unexpected, while ERPs were recorded. It was hypothesized that the children with ASD would produce the N4 effect in condition 3 but not 2. Both groups produced robust N4 effect for condition 3, but neither group produced N4 effects in condition 2.;Results are discussed in terms of possible neurophysiological mechanisms to explain the variable profile of strengths and weaknesses in ASD, as well as the hippocampus. |
