Is inhibitory control a 'no-go' in adolescents with autism spectrum disorder?

Abstract

Background: Autism spectrum disorder (ASD) refers to a range of neurodevelopmental conditions characterized by social communication deficits, repetitive behaviours, and restrictive interests. Impaired inhibition has been suggested to exacerbate the core symptoms of ASD. This is particularly critical during adolescence when social skills are maturing to adult levels. Using magnetoencephalography (MEG), we identified the location and timing pattern of neural activity associated with inhibition in adolescents with autism, compared to typically developing adolescents.

Methods: The MEG data from 15 adolescents with ASD and 15 age-matched controls (13 to 17 years) were collected during a go/no-go task with inverse ratios of go/no-go trials in two conditions: an inhibition condition (1:2) and a baseline condition (2:1). No-go trials from the two conditions were analyzed using beamformer source localizations from 200 ms to 400 ms post-stimulus onset. Significant activations were determined using permutation testing.

Results: Adolescents with ASD recruited first the right middle frontal gyrus (200 to 250 ms) followed by the left postcentral gyrus (250 to 300 ms) and finally the left middle frontal and right medial frontal gyri (300 to 400 ms). Typically developing adolescents recruited first the left middle frontal gyrus (200 to 250 ms), followed by the left superior and inferior frontal gyri (250 to 300 ms), then the right middle temporal gyrus (300 to 350 ms), and finally the superior and precentral gyri and right inferior lobule (300 to 400 ms).

Conclusions: Adolescents with ASD showed recruitment limited largely to the frontal cortex unlike typically developing adolescents who recruited parietal and temporal regions as well. These findings support the presence of an atypical, restricted inhibitory network in adolescents with ASD compared to controls.

Figure 1

Illustration of the go/no-go paradigm employed in this study, with the inhibition condition on the left (consisting of 33% no-go trials) and the baseline condition on the right (consisting of 67% no-go trials). The ‘Go’ stimuli, seen as solid black shapes, and the ‘no-go’ stimuli, seen as black shapes with an X superimposed on them, are labelled.

Figure 2

Global field power plots from frontal sensors. Upper plots: Global field power (GFP) plots from the frontal magnetoencephalography (MEG) sensors for the inhibition trials for the two conditions in the control adolescents (top plot) and the adolescents with autism spectrum disorder (ASD) (middle plot). Lower plot: Difference waveforms for Global field power (GFP) between the inhibition and baseline conditions, measured by MEG sensors over the frontal area of the brain on correct no-go trials for the two groups: control (blue) and ASD (gold). Stimulus onset is marked at 0 seconds. Four 50 ms time windows of interest are marked.

Figure 3

Locations of significant (P < 0.005) neural activations for both autism spectrum disorder (ASD) (green) and control adolescents (blue), where the inhibition condition was greater than the baseline condition, across time windows of interest. a) 200 to 250 ms b) 250 to 300 ms c) 300 to 350 ms d) 350 to 400 ms. L, left; R, right; G, gyrus; IMG, middle frontal; SFG, superior frontal; IFG, inferior frontal gyrus; MedFG, medial frontal gyrus; PostC G, postcentral gyrus; PreC G, precentral gyrus; Inf Par L, inferior parietal lobule; MTG, middle temporal gyrus; STG, superior temporal gyrus.