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| ID | Type | Description | Link |
|---|---|---|---|
| 5R01MH119189 | U.S. NIH Grant/Contract | View source |
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| Name | Class |
|---|---|
| National Institute of Mental Health (NIMH) | NIH |
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The study will use transcranial magnetic stimulation (TMS) to investigate the causal role of different brain regions during visual perception. TMS is a well-established technique used by hundreds of labs in the world. The risks associated with the technique are well understood and can be minimized by strict adherence to established safety guidelines. In the proposed study, the investigators will use TMS to specifically address the topic of how metacognitive evaluation is supported by the two prefrontal areas: the dorsolateral prefrontal cortex (DLPFC) and the anterior prefrontal cortex (aPFC). The data will be collected from healthy adults and will ultimately deepen the investigator's understanding of the mechanisms behind the normal processes related to confidence generation and metacognition.
Participants will complete a task on visual perception and receive TMS in order to assess which regions of the brain are important for confidence generation in perceptual tasks. The task will involve judging the identity of visual stimuli (oriented black-and-white gratings) and providing a confidence rating on the judgment that they performed.
The researchers will deliver TMS to several brain regions such as the anterior prefrontal cortex (aPFC), dorsolateral prefrontal cortex (DLPFC), and a control site. The researchers will then investigate participants' accuracy and confidence levels depending on where TMS was delivered. The researchers expect that aPFC TMS will decrease the metacognitive sensitivity of the participants, whereas DLPFC TMS will decrease their average confidence level. TMS will be delivered time locked to the onset of the stimulus and the researchers will investigate what is the critical period of involvement of a given region.
The TMS protocol is well within the established safety limits. Participants will be required to fill out screening and demographic forms delivered at the Center for Advanced Brain Imaging (CABI). In order to dose appropriately the TMS stimulation, it is necessary to perform motor threshold determination. Motor threshold (MT) is defined as the minimum magnetic flux needed to elicit a visual hand twitch (in the contralateral first dorsal interosseus muscle). MT is the standard in the field for determining the intensity of TMS for each individual to reduce seizure risk. The scalp region producing the largest hand twitch will be identified. At that scalp location, the lowest TMS intensity able to elicit 5 visible twitches in 10 trials at this site will be determined. Individual MT will be used to determine the intensity of stimulation for each individual, as recommended by safety guidelines. This procedure usually takes about 5 minutes and also serves the purpose of acquainting participants to TMS stimulation. In this study, the researchers will use intensities between 100 and 120% of MT, even though the safety guidelines allow for stimulation intensities of at least 130% of MT.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Healthy Adult Volunteers | Experimental | The experiment has a within-subject design where each subject will receive TMS to different brain areas. The analysis will involve comparing the effects of TMS to different regions. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Transcranial magnetic stimulation | Other | TMS will be delivered to different brain areas in order to establish their contribution to visual metacognition. |
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| Measure | Description | Time Frame |
|---|---|---|
| Average Confidence Difference With the 0 ms Condition | The average confidence difference for each delay condition and the 0 ms condition for each group (DLPFC or vertex). Confidence was self-reported together with the decision on a 4-point scale with the minimum score being one (not confident at all) and the highest score being four (very confident). The range of the scale is 1 (not confident at all) to 4 (very confident). | 6 months |
| Average Mratio Difference With the 0 ms Condition | The average Mratio difference for each delay condition and the 0 ms condition for each group (DLPFC or vertex). The Mratio is derived from signal detection theoretical modeling of the observer's decision and confidence response. It is the ratio of two measures: the observer's metacognitive sensitivity (meta-d', the ability to discriminate between correct and incorrect responses) and the observer's stimulus sensitivity (d', the ability to discriminate between the two stimulus classes). The Mratio could be calculated from subjects' self-rated confidence together with task performance. | 6 month |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Dobromir A. Rahnev, Ph.D. | Georgia Institute of Technology | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Center for Advance Brain Imaging | Atlanta | Georgia | 30332 | United States |
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| ID | Title | Description |
|---|---|---|
| FG000 | DLPFC Group | The experiment has a within-subject design where each subject will receive TMS to DLPFC at different time point (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after the stimulus presentation. |
| FG001 | Vertex Group | The experiment has a within-subject design where each subject will receive TMS to vertex at different time point (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after the stimulus presentation. |
| Title | Milestones | Reasons Not Completed | |||||||||||||||||||||
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| Overall Study |
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| ID | Title | Description |
|---|---|---|
| BG000 | DLPFC Group | The experiment has a within-subject design where each subject will receive TMS (Transcranial magnetic stimulation) at DLPFC at different time point (0 ms, 200 ms, 300 ms, 400 ms, 500 ms) after the stimulus presentation in order to reveal the timing of confidence computation in DLPFC. |
| BG001 |
| Units | Counts |
|---|---|
| Participants |
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| Title | Description | Population Description | Parameter Type | Dispersion Type | Unit of Measure | Calculate Percentage | Denominator Units Selected | Denominators | Classes |
|---|---|---|---|---|---|---|---|---|---|
| Age, Continuous | Some of the participants didn't provide the date of birth. |
| 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 | Average Confidence Difference With the 0 ms Condition | The average confidence difference for each delay condition and the 0 ms condition for each group (DLPFC or vertex). Confidence was self-reported together with the decision on a 4-point scale with the minimum score being one (not confident at all) and the highest score being four (very confident). The range of the scale is 1 (not confident at all) to 4 (very confident). | The analysis population is after the exclusion of subjects who have their 0 ms condition accuracy 3.5% lower than the average accuracy of all delay conditions | Posted | Mean | Standard Deviation | score on a scale (1-4) | 6 months |
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6 months
Any event that deviate from regular data collection.
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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 | DLPFC Group | The experiment has a within-subject design where each subject will receive TMS to DLPFC at different time point (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after the stimulus presentation. |
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| Title | Organization | Phone | Extension | |
|---|---|---|---|---|
| Dr. Dobromir Rahnev | Georgia Institute of Technology | 6466378219 | rahnev@psych.gatech.edu |
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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 | Jun 12, 2023 | Jun 13, 2023 | Prot_SAP_001.pdf |
| ICF | No | No | Yes | Informed Consent Form | Nov 16, 2021 | Jun 2, 2023 | ICF_000.pdf |
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| ID | Term |
|---|---|
| D050781 | Transcranial Magnetic Stimulation |
| ID | Term |
|---|---|
| D055909 | Magnetic Field Therapy |
| D013812 | Therapeutics |
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TMS manipulation. Within-subjects design. Each participant will receive TMS to three different sites: DLPFC, aPFC, and a control site.
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| Vertex Group |
The experiment has a within-subject design where each subject will receive TMS (Transcranial magnetic stimulation) at vertex at different time point (0 ms, 200 ms, 300 ms, 400 ms, 500 ms) after the stimulus presentation in order to reveal the timing of confidence computation in DLPFC. |
| BG002 | Total | Total of all reporting groups |
| Mean |
| Standard Deviation |
| years |
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| Sex: Female, Male | Count of Participants | Participants |
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| Race (NIH/OMB) | Count of Participants | Participants |
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| Region of Enrollment | Number | participants |
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| OG001 | DLPFC-300 ms | The study features a within-subject design in which subjects receive TMS at DLPFC at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at DLPFC, for 200 ms condition. The measurement is the confidence difference between the 300 ms condition and the 0 ms condition for DLPFC group. |
| OG002 | DLPFC-400 ms | The study features a within-subject design in which subjects receive TMS at DLPFC at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at DLPFC, for 200 ms condition. The measurement is the confidence difference between the 400 ms condition and the 0 ms condition for DLPFC group. |
| OG003 | DLPFC-500 ms | The study features a within-subject design in which subjects receive TMS at DLPFC at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at DLPFC, for 200 ms condition. The measurement is the confidence difference between the 500 ms condition and the 0 ms condition for DLPFC group. |
| OG004 | Vertex-200 ms | The study features a within-subject design in which subjects receive TMS at vertex at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at vertex, for 200 ms condition. The measurement is the confidence difference between the 200 ms condition and the 0 ms condition for vertex group. |
| OG005 | Vertex-300 ms | The study features a within-subject design in which subjects receive TMS at vertex at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at vertex, for 200 ms condition. The measurement is the confidence difference between the 300 ms condition and the 0 ms condition for vertex group. |
| OG006 | Vertex-400 ms | The study features a within-subject design in which subjects receive TMS at vertex at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at vertex, for 200 ms condition. The measurement is the confidence difference between the 400 ms condition and the 0 ms condition for vertex group. |
| OG007 | Vertex-500 ms | The study features a within-subject design in which subjects receive TMS at vertex at 5 different time points (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after stimulus presentation. This arm is for the data of subjects who receive TMS at vertex, for 200 ms condition. The measurement is the confidence difference between the 500 ms condition and the 0 ms condition for vertex group. |
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| Primary | Average Mratio Difference With the 0 ms Condition | The average Mratio difference for each delay condition and the 0 ms condition for each group (DLPFC or vertex). The Mratio is derived from signal detection theoretical modeling of the observer's decision and confidence response. It is the ratio of two measures: the observer's metacognitive sensitivity (meta-d', the ability to discriminate between correct and incorrect responses) and the observer's stimulus sensitivity (d', the ability to discriminate between the two stimulus classes). The Mratio could be calculated from subjects' self-rated confidence together with task performance. | The analysis population is after the exclusion of subjects whose 0 ms condition accuracy is 3.5% lower than the average accuracy of all four delay conditions. | Posted | Mean | Standard Deviation | Ratio | 6 month |
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| 0 |
| 50 |
| 0 |
| 50 |
| 0 |
| 50 |
| EG001 | Vertex Group | The experiment has a within-subject design where each subject will receive TMS to vertex at different time point (0 ms, 200 ms, 300 ms, 400 ms, and 500 ms) after the stimulus presentation. | 0 | 26 | 0 | 26 | 0 | 26 |
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| Native Hawaiian or Other Pacific Islander |
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| Black or African American |
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| White |
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| More than one race |
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| Unknown or Not Reported |
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