EEG
High-density Research EEG (Task-free, Visual Evoked Potentials, & Auditory tasks)
About#
High-density research EEG will be collected in the lab using standardized systems (EGI Net Amps 500 amplifiers, 128-channel nets), with size-appropriate nets available at each site to accommodate participants from infancy through adolescence. Stimuli will be presented via identically configured laptops running E-Prime 3 (provided by the CCC).
Each site will designate an EEG Site Lead with expertise in EEG who has been trained extensively in EEG data collection, including netting and cap application. All EEG staff should be highly familiar with the ARIA-IMPACT EEG protocols and procedures, which will be described in detail in the EEG MOP.
EEG data will be sampled at ≥500 Hz with an online vertex reference. The CCC will distribute a standardized acquisition template to ensure acquisition is consistent over time and across sessions. Impedances will be optimized below 50 kΩ where possible, within participant tolerance; any out-of-threshold channels will be noted in an impedance quality file saved and uploaded with each session. Stimulus onset will be recorded directly in the raw EEG file via hardware DIN triggers (a photocell for visual onset and a direct audio hardware trigger for auditory onset) alongside E-Prime event markers, and synchronized video will be recorded concurrently to support artifact identification and behavioral state coding.
Active procedures (net application, impedance checks, and all three paradigms) take approximately 25–30 minutes, of which the core paradigms account for about 15 minutes of recording. A variable amount of time is allocated at the start of the session for acclimation (0–30 minutes, depending on the participant) to ensure the participant is comfortable before netting. Total time in the EEG room will not exceed one hour. Session continuation will be guided by participant tolerance per the EEG MOP: if a participant does not tolerate cap application after three attempts with appropriate desensitization, this will be treated as non-assent and the session will not proceed; sessions will be discontinued if distress cannot be resolved and will never be prolonged in a way that could discourage future participation.
EEG Paradigms
All paradigms have been selected to be appropriate across the full age and developmental range of the study population and are presented in a fixed order for consistency across sites and timepoints. The session comprises three paradigms: a task-free block, a visual evoked potential (VEP) paradigm, and an auditory paradigm. During the task-free and auditory paradigms (but not the VEP), participants may play a preferred video of interest silently on an iPad if needed for behavioral regulation. Full details of each paradigm are extensively described in the MOP and briefly summarized below.
Task-free (6 minutes). Spontaneous resting EEG is recorded while the participant sits quietly, with no structured visual or auditory stimulation. No auditory stimuli will be presented during resting state blocks and the room will be kept as quiet as possible.
Visual Evoked Potentials (VEP) (3 minutes): Stimuli will be presented using E-Prime. A standardized contrast-reversing black-and-white checkerboard that reverses every 500 ms, with central fixation, presented in a darkened room. The checkerboard will reverse at 2 reversals per second (500ms per reversal) for a total of 360 reversals (~3 minutes). The room will be darkened and free of competing stimulation. If the participant looks away, the examiner will redirect attention by gently tapping the back of the monitor or using a brief verbal prompt.
Auditory (6 minutes). Auditory stimuli are presented at 75 dB SPL via speakers to elicit an evoked response (AEP/ASSR), with ambient noise kept low (<45 dB SPL).
Administration
| Administration type | Direct Assessment |
|---|---|
| Setting | In-Person |
| Duration | 60 min |
| Respondent | Child |
| Visits | Visits 1-3 |
| Ages |
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Quality Control#
Raw EEG data (.mff file) will be uploaded to the DCC (Lasso) immediately after collection for centralized preprocessing and quality review, performed by the CCC. EEG recordings and synchronized videos will undergo quality review within 24 hours of upload. This review will check protocol fidelity, identify technical issues, and assess overall data quality. Sites will be informed promptly of any technical issues or poor quality data.