Qualitative analysis of spontaneous electroencephalogram (EEG) recordings from participants with Dup15q syndrome revealed overt beta frequency oscillations apparent upon visual inspection. (A) EEG recordings from 9 scalp regions of interest (ROIs) were analyzed: left frontal (orange), left central (yellow), left posterior (green), mid-frontal (aquamarine), mid-central (cyan), mid-posterior (blue), right frontal (purple), right central (pink), right posterior (red). (B) 3-dimenisonal head model showing ROI electrode locations. (C) 3 s of broadband EEG recordings from a representative 29-month-old TD child from 36 channels across 9 ROIs. (D) Same duration of EEG recorded from a 27-month-old child with nonsyndromic ASD. (E) EEG from a representative Dup15q syndrome participant (age 28 months) reveals spontaneous beta oscillations (SBOs) in virtually all channels and all ROIs. The overt quality of SBOs likely allows for their easy detection in clinical EEG recordings. By contrast, (F) a 43-month-old participant with both Dup15q syndrome and epilepsy does not show nearly such distinct SBOs. It is possible that beta activity is reduced in children with both Dup15q syndrome and epilepsy.