The Attentional Networks Test (ANT) has been widely used to assess the functionality of different brain networks associated with attention (Posner, Fan). A number of studies on children with ADHD and related attention disorders have used the ANT in conjunction with functional MRI (fMRI) to determine differences in attentional network responses within the brain by observing patterns in the BOLD response. A previous study by Mutreja involved administering the ANT to autistic participants and age-matched controls, and showed that autistic children had less sensitivity in processing speed when responding to the incongruent stimuli than neurotypical children (Mutreja). The hypothesis in this research is that mildly autistic individuals have a higher level of attentional focus and are less likely to be distracted by visual stimuli outside of the area where their visual attention is focused. This study addresses whether the cortical brain areas involved in this process are different or respond differently for autistic individuals.
Objectives:
The objectives of this research were: to determine the EEG power distribution patterns of autistic and neurotypical participants; to compare the power distribution for incongruent and congruent task presentation; and to determine whether there are features within the EEG power that can be used in pattern recognition algorithms for identification of mild to very mild autism.
Methods:
Participants were recruited between the ages of 13 and 18 who were either diagnosed with mild autism or Asperger’s (in the case of diagnoses made prior to 2009), and were not verbally impaired. Individuals were diagnosed and/or screened either through the school system or a consulting psychologist. A 64-channel EGI system was used to acquire an EEG of participants while they were taking the ANT, under conditions of congruent, incongruent, and neutral stimuli in a screen room facility that isolated external visual and auditory stimuli. An in-house Matlab algorithm and EEGLAB were used for data processing.
Results:
The EEG power levels were determined for all electrode locations and averaged over the congruent and incongruent tasks (16 trials each) for both autistic subjects and controls. A non-corrected t-test was performed to determine whether there were any significant differences in EEG power levels between the two groups. For the congruent task, one feature was identified that passed the t-test: the EEG power in the alpha band in the right temporal-parietal region. For the incongruent task, seven features were identified that passed the t-test: EEG power in the left frontal-temporal region in the delta, theta, and gamma frequency ranges; in the right temporal region in the alpha, beta, and gamma frequency ranges; and in the left occipital region in the gamma frequency range.
Conclusions:
The results indicate that the brain responses as measured by EEG of autistic and neurotypical participants are similar when performing the ANT with a congruent presentation; while for the incongruent presentation, numerous areas were shown to be different. This result is consistent with the hypothesis that autistic individuals may be less distracted in the presence of incongruent flanker information than neurotypical individuals.
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