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Poster #6 - A comparative analysis of neural responses to inhibition-tasks in children with ADHD and Typical Development

Thu, March 21, 9:30 to 10:45am, Baltimore Convention Center, Floor: Level 1, Exhibit Hall B

Integrative Statement

Deficits in executive functioning (EF) are a hallmark of Attention Deficit/Hyperactivity Disorder (ADHD; Wilcutt et al., 2005), a neurobehavioral disorder characterized by impairing levels of hyperactivity, impulsivity, and/or inattention. EF is utilized when conflicting thoughts, feelings or responses must be resolved, or a learned response must be inhibited. Previous literature has focused on behavioral regulation in ADHD, however given the deficits in attentional control in children with ADHD, this study also aims to investigate inhibition and conflict monitoring through electrophysiological measures, specifically Event Related Potentials (ERP), to describe the neural profile of children with ADHD.
The current study used high-density EEG (128-channel Hyrdocel Sensor Net; EGI, Eugene OR) to record and measure continuous electrophysiological responses of 21 children with ADHD and 18 typically developing children between the ages 7-11. Specifically, the Children’s Attention Network Test (ANT) task and a Cued Go/No-Go task were administered to examine neural responses to monitoring conflicting information to suppress interfering flankers and inhibit behavioral responses on No-Go trials, respectively. N2 ERPs were calculated from the mean amplitude of Fz and two adjacent electrodes with window of 300-400 ms post-stimulus. The P3 ERP mean amplitude was calculated at Pz and two adjacent electrodes with a window of 400-700 ms post-stimulus.
The Children’s ANT flanker task presents a target animal is flanked by other animals with either the same (congruent) or opposite (incongruent) orientation. Participants were asked to press a button corresponding to the direction of the target. The Cued Go/No-Go involves ‘feeding’ alphabet soup to a dog by pressing a button each time a letter appears. Two letters require a response (i.e., Go) while a third requires inhibition (i.e., Nogo). The ERP components measured reflect conflict monitoring between the differing conditions (i.e., N2) and response inhibition (i.e., P3).
Mixed factor ANOVAs were conducted to assess differences in amplitude between the two groups of children across trial conditions (ANT, incongruent and congruent; Go/No-Go, Go and No-Go). There was a significant group by condition interaction for the ANT task (F(1,37)=4.076, p=.051), and post-hoc t-test showed a more negative Flanker N2 component for the ADHD group (M=-1.55mV, SD=4.72) during incongruent trials compared to the TD group ((M=-.97mV, SD=3.41); t(37)= p=.0673). Groups did not differ for the N2 component of either condition of the Go/No-Go task (p’s>.05). For the P3 component, there were no significant differences found between groups or conditions for either the ANT and Go/No-Go tasks (p’s>.05).
These results suggest that children with ADHD exhibit a different pattern of neural responses during interference monitoring and suppression. Specifically, they engage relatively more neural resources for interfering information than the comparison group (i.e., more negative Flanker N2 during incongruent trials). These results add to the current literature by suggesting that in comparison to their age-matched TD peers, children with ADHD exhibit more difficulty on a neural basis when detecting and resolving conflicting information. The current study is ongoing and the researchers anticipate collecting data from approximately 15 additional participants (10 TD, 5 ADHD).

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