Neuroscience from the comfort of your home: Repeated, self-administered wireless dry EEG measures brain function with high fidelity

Abstract

Recent advances have enabled the creation of wireless, "dry" electroencephalography (EEG) recording systems, and easy-to-use engaging tasks, that can be operated repeatedly by naïve users, unsupervised in the home. Here, we evaluated the validity of dry-EEG, cognitive task gamification, and unsupervised home-based recordings used in combination. Two separate cohorts of participants-older and younger adults-collected data at home over several weeks using a wireless dry EEG system interfaced with a tablet for task presentation. Older adults (n = 50; 25 females; mean age = 67.8 years) collected data over a 6-week period. Younger male adults (n = 30; mean age = 25.6 years) collected data over a 4-week period. All participants were asked to complete gamified versions of a visual Oddball task and Flanker task 5-7 days per week. Usability of the EEG system was evaluated via participant adherence, percentage of sessions successfully completed, and quantitative feedback using the System Usability Scale. In total, 1,449 EEG sessions from older adults (mean = 28.9; SD = 6.64) and 684 sessions from younger adults (mean = 22.87; SD = 1.92) were collected. Older adults successfully completed 93% of sessions requested and reported a mean usability score of 84.5. Younger adults successfully completed 96% of sessions and reported a mean usability score of 88.3. Characteristic event-related potential (ERP) components-the P300 and error-related negativity-were observed in the Oddball and Flanker tasks, respectively. Using a conservative threshold for inclusion of artifact-free data, 50% of trials were rejected per at-home session. Aggregation of ERPs across sessions (2-4, depending on task) resulted in grand average signal quality with similar Standard Measurement Error values to those of single-session wet EEG data collected by experts in a laboratory setting from a young adult sample. Our results indicate that easy-to-use task-driven EEG can enable large-scale investigations in cognitive neuroscience. In future, this approach may be useful in clinical applications such as screening and tracking of treatment response.

Keywords: Standard Measurement Error; cognition; dry electroencephalography; electroencephalography; gamification; humans; longitudinal; signal quality.

Figure 1

Screenshots of the gamified Oddball task. (A) Screenshots of the stimulus presentation, (B) Instruction screen in the Older Adult Study, (C) Instruction screen in the Younger Adult Study.

Figure 2

Screenshots of Gamified Adaptive Flanker task. (A) Instruction screen, (B) Screenshots of the stimulus presentation.

Figure 3

Cumulus dry EEG recording headset. (A) Positioning of the headset on the head. (B) Interior of the dry EEG cap. (C) Dry EEG electrode. (D) Screenshot of the built-in calibration step in the mobile app. Figure adapted from McWilliams et al. (52).

Figure 4

Weekly at-home adherence to the experimental protocol. Data in purple correspond to the Older Adult study (N = 50). Data presented in blue correspond to the Younger Adult study (N = 30). Error bars represent 95% confidence intervals. The gray areas correspond to the number of at-home sessions requested in the protocol. The number of sessions requested varied as per protocol, to accommodate scheduled in-lab sessions.

Figure 5

Median System Usability Scale component scores across all participants in the Data of Older Adult study are depicted in purple (N = 32), and of the Younger Adult Study in blue (N = 18). Whiskers denote interquartile range. Datapoints outside of the 1.5*interquartile ranges were defined as outliers.

Figure 6

Percentage of available sessions after pre-processing per channel. The top row corresponds to data collected in the Older Adult study. The bottom row corresponds to data collected during the Younger Adult study. The left column of each figure corresponds to data collected during the gamified Oddball task, the right column of each quadrant to data collected during the gamified Flanker task.

Figure 7

ERPs analyses extracted from the Younger Adult Study (N = 30). Top row: Grand study average computed across all participants. Middle row: Standardized Measurement Errors per number of trials. The gray continuous lines correspond to the number of participants remaining in the SME calculation after trial rejection. Bottom Row: Mean numbers of trials available after preprocessing. The black dotted lines correspond to the mean numbers of trials extracted from the wet EEG study. From left to right: Target Trials extracted from the Oddball task at electrode Pz, Correct Trials extracted from the Flanker task at electrode FCz, Error Trials extracted from the Flanker task at electrode FCz. The shaded areas correspond to the 95% confidence intervals.

Figure 8

Standardized Measurement Errors per number of trials of data collected in the laboratory under researcher supervision extracted from the Younger Adult Study (N = 30). The blue line corresponds to data collected in the laboratory. The gray line corresponds to data collected in the home. The black dotted lines correspond to the mean numbers of trials extracted from the wet EEG study. From left to right: Target Trials extracted from the Oddball task at electrode Pz, Correct Trials extracted from the Flanker task at electrode FCz, Error Trials extracted from the Flanker task at electrode FCz. The shaded areas correspond to the 95% confidence intervals.

Figure 9

ERPs analyses extracted from the Older Adult Study (N = 50). Top row: Grand study average computed across all participants. Middle row: Standardized Measurement Errors per number of trials. The gray continuous lines correspond to the number of participants remaining in the SME calculation after trial rejection. Bottom Row: Mean numbers of trials available after preprocessing. The black dotted lines correspond to the mean numbers of trials extracted from the wet EEG study. From left to right: Target Trials extracted from the Oddball task at electrode Pz, Correct Trials extracted from the Flanker task at electrode FCz, Error Trials extracted from the Flanker task at electrode FCz. The shaded areas correspond to the 95% confidence intervals.

Figure 10

Standardized Measurement Errors per number of trials of data collected in the laboratory under researcher supervision extracted from the Older Adult Study (N = 50). The purple line corresponds to data collected in the laboratory. The gray line corresponds to data collected in the home. The black dotted lines correspond to the mean numbers of trials extracted from the wet EEG study. From left to right: Target Trials extracted from the Oddball task at electrode Pz, Correct Trials extracted from the Flanker task at electrode FCz, Error Trials extracted from the Flanker task at electrode FCz. The shaded areas correspond to the 95% confidence intervals.