Neural Response to Cued Fixation in Children with and without Autism Spectrum Disorder (ASD)

Background: Accumulating evidence suggests that children with ASD have impaired attention processing. However, the results of studies evaluating deficits in the alerting attention system, which signals readiness to receive information, are mixed. Neural measures of low-level attention processing, such as the P1 ERP component, may clarify group differences in the efficacy of the alerting system. To test this, we compared P1 amplitude following a cued fixation during a Flanker Task in a sample of children with ASD and typically developing (TD) controls. Additionally, we assessed habituation of the P1 in response to the cue, to explore group differences in sensitivity of the alerting system over time.

Objectives: The objectives of these preliminary analyses were to (1) determine if P1 amplitude in response to a cued fixation differs between children with ASD and TD children, and (2) assess change in P1 amplitude over time during a Flanker task.

Methods: As part of a larger study, ERP data was derived from 24 children with ASD (22 males, M_age=9.24±1.16 years) and 21 TD children (19 males, M_age=8.83±1.41 years) during a Flanker task. Each trial began with the presentation a fixation cue (450ms) that was paired with a tone (150ms). The cue was then followed by congruent and incongruent stimuli (2000ms). During each trial, children were prompted to respond to the center, target stimulus via button press on a response box.

Only trials with correct responses were included in analyses. In order to evaluate the change in neural response to the cue over time, we computed P1 amplitude separately for the first (54 trials) and second (54 trials) halves of the task. P1 amplitude was derived from electrode Oz 70-170ms after the cue was presented. A repeated-measures ANCOVA (controlling for child age) was run to compare P1 amplitude between diagnostic groups (between-subjects factor) and across time (within-subjects factor).

Results: Counter to our prediction, the main effect of group was not significant (p=0.519). Interestingly, however, the significant main effect of time indicated that children habituate to the cued fixation (F(1,42)=6.255, p=0.016), regardless of diagnostic group (time by group interaction: p=0.905). Although the main effect of age was not significant (p=0.483), the significant time by age interaction (F(1,42)=5.893, p=0.020) suggested that older children habituate to the cue less over time (r=-0.352, p=0.018).

Conclusions: Collectively, these results indicate that children habituate to cued fixations. Importantly, neural responses to the cue were similar among children with ASD and TD children, suggesting that the alerting system may be intact in this clinical population at this stage of development. In the next several months, we plan to (1) increase our sample size to explore the age effect and (2) evaluate relations between P1 in response to the cue and other ERP components that index downstream attentional processes (i.e., N2).