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The purpose of this clinical trial is to investigate the feasibility and efficacy of non-invasive transcranial alternating current stimulation (tACS) at gamma frequency in enhancing memory recall and modulating sleep network dynamics measured by at-home electroencephalography (EEG) in healthy elderly people. Eligible participants will first collect sleep EEG at home for one night to acclimate to the data collection during sleep. Participants are then randomized into first undergoing either tACS at gamma band frequencies (i.e. 40Hz) or tACS at a control frequency (i.e. 21Hz). Stimulation is administered in the lab during a cognitive testing battery that includes memorizing items. After a night of sleep with EEG at home, participants return to the lab the following day to measure memory recall. Recall is performed again after five days. This sequence of encoding during stimulation in the lab, sleep EEG at home for one night, and recall is then repeated for the other stimulation condition about a week later. Participants are wearing an actigraphy wristband throughout the study period.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| First gamma (40Hz) stimulation, then active control (21Hz) stimulation | Experimental | After collecting sleep EEG at home for one night to acclimate to the data collection during sleep, participants first receive gamma (40Hz) tACS on Day 1 followed by a 5-9 day washout. Participants then receive active control (21Hz) stimulation. |
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| First active control (21 Hz) stimulation, then gamma (40 Hz) stimulation | Experimental | After collecting sleep EEG at home for one night to acclimate to the data collection during sleep, participants first receive active control (21Hz) tACS on Day 1 followed by a 5-9 day washout. Participants then receive gamma (40Hz) stimulation. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Gamma transcranial alternating current stimulation | Device | tACS (gamma frequency, 40Hz) during cognitive testing (about 40 minutes duration). |
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| Measure | Description | Time Frame |
|---|---|---|
| Percent of Participants Tolerating Cognitive Testing During tACS | To establish acceptability of tACS combined with cognitive testing in healthy elderly participants and will be considered acceptable if at least >/= 80% of participants tolerate the procedure. | Baseline (Day 1) |
| Verbal Memory at Day 1 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words on the same day. The number of correctly remembered words will be recorded. | Baseline (Day 1) |
| Verbal Memory at Day 2 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words on the day after. The number of correctly remembered words will be recorded. | Follow-Up (Day 2) |
| Verbal Memory at Day 5 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words after 5 days. The number of correctly remembered words will be recorded. | Follow-Up (Day 5) |
| Associative Verbal Memory at Day 1 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs on the same day. The number of correctly remembered word pairs will be recorded. | Baseline (Day 1) |
| Associative Verbal Memory at Day 2 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs on the day after. The number of correctly remembered word pairs will be recorded. |
| Measure | Description | Time Frame |
|---|---|---|
| Performance in Phonematic Fluency-Correct Words | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task during 1 minute. The number of correct words will be calculated. | Baseline (Day 1), Follow-Up (Day 2) |
| Performance in Phonematic Fluency-Perseverations |
| Measure | Description | Time Frame |
|---|---|---|
| Exploration of a Relationship (Correlation) Between the Amount of Sleep Spindles and Slow Wave Sleep With Recall | A relationship is defined as a correlation (Pearson's) between memory recall performance (amount of words recalled) and sleep EEG features (especially spindles, slow waves), i.e., whether better memory recall is associated with more sleep spindles and more slow wave sleep in the night after stimulation. |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Flavio Frohlich, PhD | University of North Carolina, Chapel Hill | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Carolina Center for Neurostimulation | Chapel Hill | North Carolina | 27516 | United States |
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| ID | Title | Description |
|---|---|---|
| FG000 | First Gamma (40Hz) Stimulation, Then Active Control (21Hz) Stimulation | After collecting sleep EEG at home for one night to acclimate to the data collection during sleep, participants first receive gamma (40Hz) tACS on Day 1 followed by a 5-9 day washout. Participants then receive active control (21Hz) stimulation. Gamma transcranial alternating current stimulation: tACS (gamma frequency, 40Hz) during cognitive testing (about 40 minutes duration). Control transcranial alternating current stimulation: tACS (control frequency, 21Hz) during cognitive testing (about 40 minutes duration). EEG headband: At-home, ambulatory, single-channel EEG headband which records brain activity during sleep Actigraphy wristband: At-home, ambulatory, wrist-worn accelerometer which records levels of motor activity during the whole day |
| FG001 | First Active Control (21 Hz) Stimulation, Then Gamma (40 Hz) Stimulation | After collecting sleep EEG at home for one night to acclimate to the data collection during sleep, participants first receive active control (21Hz) tACS on Day 1 followed by a 5-9 day washout. Participants then receive gamma (40Hz) stimulation. Gamma transcranial alternating current stimulation: tACS (gamma frequency, 40Hz) during cognitive testing (about 40 minutes duration). Control transcranial alternating current stimulation: tACS (control frequency, 21Hz) during cognitive testing (about 40 minutes duration). EEG headband: At-home, ambulatory, single-channel EEG headband which records brain activity during sleep Actigraphy wristband: At-home, ambulatory, wrist-worn accelerometer which records levels of motor activity during the whole day |
| Title | Milestones | Reasons Not Completed | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| First Intervention |
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| Washout (9 Days) |
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| Second Intervention |
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| ID | Title | Description |
|---|---|---|
| BG000 | All Participants | Participants who received transcranial alternating current stimulation: tACS. |
| Units | Counts |
|---|---|
| Participants |
|
| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Customized | Count of Participants |
| Type | Title | Description | Population Description | Reporting Status | Anticipated Posting Date | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Time Frame | Units Analyzed | Denominator Units Selected | Arm/Group Information | Denominators | Classes | Analyses | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Primary | Percent of Participants Tolerating Cognitive Testing During tACS | To establish acceptability of tACS combined with cognitive testing in healthy elderly participants and will be considered acceptable if at least >/= 80% of participants tolerate the procedure. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Number | percentage of participants | Baseline (Day 1) |
|
From the first intervention administration through follow-up, up to 14 days later.
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| ID | Title | Description | Deaths (Affected) | Deaths (At Risk) | Serious Events (Affected) | Serious Events (At Risk) | Other Events (Affected) | Other Events (At Risk) |
|---|---|---|---|---|---|---|---|---|
| EG000 | First Gamma (40Hz) Stimulation | Participants who received gamma (40Hz) tACS Gamma transcranial alternating current stimulation: tACS (gamma frequency, 40Hz) during cognitive testing (about 40 minutes duration). |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Andrea Seiler, MD | University of North Carolina at Chapel Hill | +41 316322111 | andrea.seiler@insel.ch |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_SAP | Yes | Yes | No | Study Protocol and Statistical Analysis Plan | Aug 15, 2023 | Nov 19, 2024 | Prot_SAP_000.pdf |
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| ID | Term |
|---|---|
| D060825 | Cognitive Dysfunction |
| ID | Term |
|---|---|
| D003072 | Cognition Disorders |
| D019965 | Neurocognitive Disorders |
| D001523 | Mental Disorders |
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| Control transcranial alternating current stimulation | Device | tACS (control frequency, 21Hz) during cognitive testing (about 40 minutes duration). |
|
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| EEG headband | Device | At-home, ambulatory, single-channel EEG headband which records brain activity during sleep |
|
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| Actigraphy wristband | Device | At-home, ambulatory, wrist-worn accelerometer which records levels of motor activity during the whole day |
|
| Follow-Up (Day 2) |
| Associative Verbal Memory at Day 5 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs after 5 days. The number of correctly remembered word pairs will be recorded. | Follow-Up (Day 5) |
| Percentage of Participants in Which it is Possible to Obtain at Least 4 Hours EEG Recording | To establish feasibility of at-home use of a single-channel EEG device during sleep. This will be considered feasible if the device has been worn for at least 4 hours during the first night for >/= 80% of participants. | Baseline (Day 1) |
| Percentage of Participants Who Wear the EEG Device During All Three Nights for at Least 4 Hours | To establish acceptability of at-home use of the single-channel EEG device during multiple nights. Acceptability will be considered as given if the device has been worn for at least 4 hours during each of the three nights in >/=80% of participants. | Baseline (Day 1) |
| Amount of Sleep Spindles in Sleep-EEG | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the number of sleep spindles occuring during the night after the intervention. Sleep spindles during the first two hours of sleep-EEG will be counted. A sleep spindle is defined as a train of sinusoidal waves with frequency 11-16 Hz and a duration of at least 0.5 seconds. | Baseline (Day 1) |
| Amount of Slow Wave Sleep in Sleep-EEG | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the amount of slow wave sleep (deep/delta sleep) occuring during the night after the intervention. The amount of slow wave sleep during the first two hours of sleep-EEG will be counted. | Baseline (Day 1) |
To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task (i.e. production of words that start with a specific letter) during 1 minute. Number of correct words, number of perseverations and number of rule breaks will be calculated. |
| Baseline (Day 1), Follow-Up (Day 2) |
| Performance in Phonematic Fluency-Rule Breaks | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task during 1 minute. Number of correct words, number of perseverations and number of rule breaks will be calculated. | Baseline (Day 1), Follow-Up (Day 2) |
| Executive Functioning (Time to Complete Stroop Test) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the Stroop Color and Word Test during and on the day after the intervention. Time for test completion and errors will be calculated. Selective attention was evaluated with the Stroop Color Word Interference Test. In the interference portion of this test, the subject identifies the color of ink in which words ("red", "green", or "blue") are printed, requiring the subject to inhibit their natural tendency to read the word. A subject's score is the time taken to identify 50 stimulus items. The time taken to complete the maze is inversely proportional to the cognitive function. | Baseline (Day 1), Follow-Up (Day 2) |
| Executive Functioning (Trail Making Test) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the Trail Making Test (TMT; connecting a set of numbers and numbers and letters as quickly as possible while maintaining accuracy) during and on the day after the intervention. The TMT (Part A and Part B) is a measure of visuomotor processing/sequencing speed. Participants must draw a line connecting numbers in ascending order as quickly as possible. Completion time in seconds is recorded (0-120, where lower scores represent better performance). Completion time of Part B is divided by completion time of Part A (Ratio B/A). | Baseline (Day 1), Follow-Up (Day 2) |
| Attentional Performance (TAP) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on subtests of the Test of Attentional Performance (TAP) during and on the day after the intervention. Percentile ranks for the following subtests will be calculated: Alertness (reaction time under two conditions), Go/NoGo (stimuli that require a selective reaction, that is, to react or not to react), Divided Attention (a visual and an auditory task must be processed in parallel), Visual Scanning (a matrix-like arrangement of 5 x 5 stimuli is used, the aim being to detect whether this arrangement includes a critical stimulus or not). | Baseline (Day 1), Follow-Up (Day 2) |
| Baseline (Day 1), Follow-Up (Day 2) |
| Exploration of a Relationship (Correlation) of Sleep-Wake-Schedule Changes and Type of Stimulation | To see whether there is a correlation (Pearson's) between type of stimulation/wearing EEG and the motor activity pattern (measured by actigraphy wristband). | Baseline (Day 1), Follow-Up (Day 2) |
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| NOT COMPLETED |
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| Participants |
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| Sex: Female, Male | Count of Participants | Participants |
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| Ethnicity (NIH/OMB) | Count of Participants | Participants |
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| Race (NIH/OMB) | Count of Participants | Participants |
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| Region of Enrollment | Count of Participants | Participants |
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Participants who received (21Hz) tACS
Control transcranial alternating current stimulation: tACS (control frequency, 21Hz) during cognitive testing (about 40 minutes duration).
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| Primary | Verbal Memory at Day 1 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words on the same day. The number of correctly remembered words will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of words recalled | Baseline (Day 1) |
|
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| Primary | Verbal Memory at Day 2 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words on the day after. The number of correctly remembered words will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of words recalled | Follow-Up (Day 2) |
|
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| Primary | Verbal Memory at Day 5 | Participants will memorize 15 words ("Rey Auditory Verbal Learning Test") during gamma-tACS or control-tACS. They will be required to recall the words after 5 days. The number of correctly remembered words will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of words recalled | Follow-Up (Day 5) |
|
|
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| Primary | Associative Verbal Memory at Day 1 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs on the same day. The number of correctly remembered word pairs will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of word pairs recalled | Baseline (Day 1) |
|
|
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| Primary | Associative Verbal Memory at Day 2 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs on the day after. The number of correctly remembered word pairs will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of word pairs recalled | Follow-Up (Day 2) |
|
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| Primary | Associative Verbal Memory at Day 5 | Participants will memorize 8 word-pairs during gamma-tACS or control-tACS. They will be required to recall the pairs after 5 days. The number of correctly remembered word pairs will be recorded. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of word pairs recalled | Follow-Up (Day 5) |
|
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| Primary | Percentage of Participants in Which it is Possible to Obtain at Least 4 Hours EEG Recording | To establish feasibility of at-home use of a single-channel EEG device during sleep. This will be considered feasible if the device has been worn for at least 4 hours during the first night for >/= 80% of participants. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Number | percentage of participants | Baseline (Day 1) |
|
|
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| Primary | Percentage of Participants Who Wear the EEG Device During All Three Nights for at Least 4 Hours | To establish acceptability of at-home use of the single-channel EEG device during multiple nights. Acceptability will be considered as given if the device has been worn for at least 4 hours during each of the three nights in >/=80% of participants. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Number | percentage of participants | Baseline (Day 1) |
|
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| Primary | Amount of Sleep Spindles in Sleep-EEG | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the number of sleep spindles occuring during the night after the intervention. Sleep spindles during the first two hours of sleep-EEG will be counted. A sleep spindle is defined as a train of sinusoidal waves with frequency 11-16 Hz and a duration of at least 0.5 seconds. | Data were not properly collected for some participants due to technical difficulties. | Posted | Mean | Standard Deviation | Number of sleep spindles | Baseline (Day 1) |
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| Primary | Amount of Slow Wave Sleep in Sleep-EEG | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the amount of slow wave sleep (deep/delta sleep) occuring during the night after the intervention. The amount of slow wave sleep during the first two hours of sleep-EEG will be counted. | Data were not properly collected for some participants due to technical difficulties. | Posted | Mean | Standard Deviation | minutes | Baseline (Day 1) |
|
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| Secondary | Performance in Phonematic Fluency-Correct Words | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task during 1 minute. The number of correct words will be calculated. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | Number of correct words | Baseline (Day 1), Follow-Up (Day 2) |
|
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| Secondary | Performance in Phonematic Fluency-Perseverations | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task (i.e. production of words that start with a specific letter) during 1 minute. Number of correct words, number of perseverations and number of rule breaks will be calculated. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | number of perseverations | Baseline (Day 1), Follow-Up (Day 2) |
|
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| Secondary | Performance in Phonematic Fluency-Rule Breaks | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on a phonematic fluency-task during 1 minute. Number of correct words, number of perseverations and number of rule breaks will be calculated. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | number of rule breaks | Baseline (Day 1), Follow-Up (Day 2) |
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| Secondary | Executive Functioning (Time to Complete Stroop Test) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the Stroop Color and Word Test during and on the day after the intervention. Time for test completion and errors will be calculated. Selective attention was evaluated with the Stroop Color Word Interference Test. In the interference portion of this test, the subject identifies the color of ink in which words ("red", "green", or "blue") are printed, requiring the subject to inhibit their natural tendency to read the word. A subject's score is the time taken to identify 50 stimulus items. The time taken to complete the maze is inversely proportional to the cognitive function. | One participant was not exposed to 40 Hz due to their time constraints. | Posted | Mean | Standard Deviation | seconds | Baseline (Day 1), Follow-Up (Day 2) |
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| Secondary | Executive Functioning (Trail Making Test) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on the Trail Making Test (TMT; connecting a set of numbers and numbers and letters as quickly as possible while maintaining accuracy) during and on the day after the intervention. The TMT (Part A and Part B) is a measure of visuomotor processing/sequencing speed. Participants must draw a line connecting numbers in ascending order as quickly as possible. Completion time in seconds is recorded (0-120, where lower scores represent better performance). Completion time of Part B is divided by completion time of Part A (Ratio B/A). | One participant was not exposed to 40 Hz due to their time constraints. Data were missing for another participant. | Posted | Mean | Standard Deviation | ratio | Baseline (Day 1), Follow-Up (Day 2) |
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| Secondary | Attentional Performance (TAP) | To investigate the effect of a single session of gamma-tACS (compared to control-tACS) on subtests of the Test of Attentional Performance (TAP) during and on the day after the intervention. Percentile ranks for the following subtests will be calculated: Alertness (reaction time under two conditions), Go/NoGo (stimuli that require a selective reaction, that is, to react or not to react), Divided Attention (a visual and an auditory task must be processed in parallel), Visual Scanning (a matrix-like arrangement of 5 x 5 stimuli is used, the aim being to detect whether this arrangement includes a critical stimulus or not). | Data are missing for some participants due to technical reasons resulting in data not being saved. | Posted | Mean | Standard Deviation | percentile rank | Baseline (Day 1), Follow-Up (Day 2) |
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| Other Pre-specified | Exploration of a Relationship (Correlation) Between the Amount of Sleep Spindles and Slow Wave Sleep With Recall | A relationship is defined as a correlation (Pearson's) between memory recall performance (amount of words recalled) and sleep EEG features (especially spindles, slow waves), i.e., whether better memory recall is associated with more sleep spindles and more slow wave sleep in the night after stimulation. | Not Posted | Baseline (Day 1), Follow-Up (Day 2) | Participants |
| Other Pre-specified | Exploration of a Relationship (Correlation) of Sleep-Wake-Schedule Changes and Type of Stimulation | To see whether there is a correlation (Pearson's) between type of stimulation/wearing EEG and the motor activity pattern (measured by actigraphy wristband). | Not Posted | Baseline (Day 1), Follow-Up (Day 2) | Participants |
| 0 |
| 10 |
| 0 |
| 10 |
| 0 |
| 10 |
| EG001 | First Active Control (21 Hz) Stimulation | Participants who received (21Hz) tACS Control transcranial alternating current stimulation: tACS (control frequency, 21Hz) during cognitive testing (about 40 minutes duration). | 0 | 11 | 0 | 11 | 0 | 11 |
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| Baseline (Day 1) Go/NoGo |
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| Baseline (Day 1) Divided Attention Acoustic |
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| Baseline (Day 1) Divided Attention Visual |
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| Baseline (Day 1) Visual Scanning Critical |
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| Baseline (Day 1) Visual Scanning Non-Critical |
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| Follow-Up (Day 2) Alertness |
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| Follow-Up (Day 2) Go/NoGo |
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| Follow-Up (Day 2) Divided Attention Acoustic |
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| Follow-Up (Day 2) Divided Attention Visual |
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| Follow-Up (Day 2) Visual Scanning Critical |
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| Follow-Up (Day 2) Visual Scanning Non-Critical |
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