Decreased Modulation of EEG Oscillations in High-Functioning Autism during a Motor Control Task

Abstract

Autism spectrum disorders (ASD) are thought to result in part from altered cortical excitatory-inhibitory balance; this pathophysiology may impact the generation of oscillations on electroencephalogram (EEG). We investigated premotor-parietal cortical physiology associated with praxis, which has strong theoretical and empirical associations with ASD symptomatology. Twenty five children with high-functioning ASD (HFA) and 33 controls performed a praxis task involving the pantomiming of tool use, while EEG was recorded. We assessed task-related modulation of signal power in alpha and beta frequency bands. Compared with controls, subjects with HFA showed 27% less left central (motor/premotor) beta (18–22 Hz) event-related desynchronization (ERD; p = 0.030), as well as 24% less left parietal alpha (7–13 Hz) ERD (p = 0.046). Within the HFA group, blunting of central ERD attenuation was associated with impairments in clinical measures of praxis imitation (r = −0.4; p = 0.04) and increased autism severity (r = 0.48; p = 0.016). The modulation of central beta activity is associated, among other things, with motor imagery, which may be necessary for imitation. Impaired imitation has been associated with core features of ASD. Altered modulation of oscillatory activity may be mechanistically involved in those aspects of motor network function that relate to the core symptoms of ASD.

Autism, Attention, and Alpha Oscillations: An Electrophysiological Study of Attentional Capture

“…For example, infants at high-risk for ASD (36), as well as children (37, 38) and adults (39) with ASD have shown reduced power in the alpha-band frequencies. Studies examining task-related changes in alpha power in ASD have reported reduced alpha-band ERS, indicative of impaired suppression of task-irrelevant sensory information (5), reduced ERD during the preparation and execution of a motor control task (40), and increased frontal ERS, which may be related to the use of alternative strategies in ASD (41). Together, these findings suggest that ASD is associated with spontaneous and task-related differences in alpha power.…”

Altered task‐related modulation of long‐range connectivity in children with autism

“…In a previous report using EEG to study dyspraxia in children with ASD [Ewen et al, ], we observed decreased‐magnitude of regional task‐related power modulation (ERD) in alpha (7–13 Hz) and beta (18–23 Hz) bands. ASD‐related decreases in alpha ERD were specific to posterior (parietal) scalp regions, and decreases in beta ERD were specific to central scalp regions.…”

“…The EEG dataset analyzed here is the same data used in the ERD analysis [Ewen et al, ]. The experimental protocol and consenting process were approved by the Johns Hopkins Medicine Institutional Review Board.…”

“…The praxis network, as established by lesion studies, consists of left‐hemisphere premotor and inferior parietal regions [Wheaton & Hallett, ]. Physiological studies further demonstrate task‐related activations of the homologous right‐hemisphere regions [Bohlhalter et al, ; Ewen et al, ; Wheaton et al, ]. Previous EEG work has demonstrated that bilateral central (motor/premotor) and parietal scalp regions demonstrate event‐related desynchronization (ERD) of alpha‐ and beta‐band activity [Ewen et al, ; Wheaton & Hallett, ] and event‐related synchronization (ERS) in the theta band during both praxis gesture production and imagining.…”

Lack of Cortical Correlates of Response Inhibition in 6-Year-Olds Born Extremely Preterm – Evidence from a Go/NoGo Task in Magnetoencephalographic Recordings

“…This suppression was, however, significantly weaker in the EPT than FT children, which may reflect reduced ability to engage the stimulus-relevant brain networks into active information processing. In a recent experiment, a group of autistic children showed reduced posterior alpha-band suppression in comparison with typically developing children while pantomiming tool use (Ewen et al, 2016). Decreased modulation of alpha oscillation was interpreted to indicate decreased task-related activation.…”