Trial Outcomes & Findings for Analysis of Electrocorticographic Signals (NCT NCT03785028)

NCT ID: NCT03785028

Last Updated: 2024-05-01

Results Overview

This experiment will use a machine learning analysis -- multivariate pattern classification -- to "decode" the brain signals measured by the electrocorticography electrodes. That is, the analysis will determine if the face/word/scene that is being remembered is being represented by these particular brain signals). The primary outcome will be to assess what happens to the neural representation of, say, a face, when the patient is probed that the other stimulus presented on that trial will be tested first - i.e., the analysis will assess the decodability of the two items as a function of their priority for upcoming task demands. Reported here is the categorical performance of Support Vector Machines (SVMs) trained using a 10-fold cross-validation procedure to decode the prioritized and unprioritized memory items (faces, scenes, or words).

• Recruitment status: COMPLETED
• Study phase: NA
• Target enrollment: 5 participants
• Primary outcome timeframe: Twenty minutes
• Results posted on: 2024-05-01

Participant Flow

Participants undergoing surgery for epilepsy were recruited at UW hospital Neurology clinic in Madison, Wisconsin, from 7/19/19 - 2/27/21.

Participant milestones

Measure	Experimental Arm 1 session of a computer-based visual working memory task (\~20 minutes total) with concurrent electrocorticography (ECoG) recording.
Overall Study STARTED	5
Overall Study COMPLETED	5
Overall Study NOT COMPLETED	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Analysis of Electrocorticographic Signals

Baseline characteristics by cohort

Measure	Experimental Arm n=5 Participants Participants will undergo working memory and attention tasks
Age, Continuous	36.4 years STANDARD_DEVIATION 16.2 • n=5 Participants
Sex: Female, Male Female	2 Participants n=5 Participants
Sex: Female, Male Male	3 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	3 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	2 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants
Race (NIH/OMB) Asian	0 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants
Race (NIH/OMB) White	3 Participants n=5 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	2 Participants n=5 Participants
Region of Enrollment United States	5 participants n=5 Participants

PRIMARY outcome

Timeframe: Twenty minutes

Population: Data collected from 4 participants, reported here as a group. Three of them completed 5 blocks of 20 trials each, resulting in a total of 100 trials, and one of them completed 4 blocks, 80 trials in total. One participant struggled to perform the task so data were not interpretable.

This experiment will use a machine learning analysis -- multivariate pattern classification -- to "decode" the brain signals measured by the electrocorticography electrodes. That is, the analysis will determine if the face/word/scene that is being remembered is being represented by these particular brain signals). The primary outcome will be to assess what happens to the neural representation of, say, a face, when the patient is probed that the other stimulus presented on that trial will be tested first - i.e., the analysis will assess the decodability of the two items as a function of their priority for upcoming task demands. Reported here is the categorical performance of Support Vector Machines (SVMs) trained using a 10-fold cross-validation procedure to decode the prioritized and unprioritized memory items (faces, scenes, or words).

Outcome measures

Measure	Theta n=1 group of all participants 3-7 Hz	Alpha n=1 group of all participants 8-12 Hz	Beta n=1 group of all participants 13-20 Hz	Gamma n=1 group of all participants 30-60 Hz (low); 60-200 Hz (high)
Qualitative Measure: Prioritization Cue-related Changes in the Neural Representation of Stimuli Reported as Binary for Prioritized and Unprioritized Item Decodability Decoded - Prioritized item	1 group of all participants	1 group of all participants	1 group of all participants	0 group of all participants
Qualitative Measure: Prioritization Cue-related Changes in the Neural Representation of Stimuli Reported as Binary for Prioritized and Unprioritized Item Decodability Not Decoded - Prioritized item	0 group of all participants	0 group of all participants	0 group of all participants	1 group of all participants
Qualitative Measure: Prioritization Cue-related Changes in the Neural Representation of Stimuli Reported as Binary for Prioritized and Unprioritized Item Decodability Decoded - Unprioritized item	1 group of all participants	1 group of all participants	0 group of all participants	0 group of all participants
Qualitative Measure: Prioritization Cue-related Changes in the Neural Representation of Stimuli Reported as Binary for Prioritized and Unprioritized Item Decodability Not decoded - Unprioritized item	0 group of all participants	0 group of all participants	1 group of all participants	1 group of all participants

PRIMARY outcome

Timeframe: Twenty minutes

Population: Data collected from a single participant, participant had electrodes positioned in each of the target regions to be analyzed to support a within-subject comparison.

Phase-amplitude coupling (PAC) refers to the synchrony between low frequency oscillations and bursts of high-frequency signal, which is interpreted as a proxy for neuronal firing. The primary outcome measure is whether the level of phase-amplitude coupling associated with a stimulus will change (increase, decrease, change to different frequencies) after that stimulus is prioritized or deprioritized by the cue. Reported here is the direction of PAC between low theta oscillations (6 Hz) and high-gamma bursts (>140 Hz) in binary terms according to whether the PAC increased or decreased for the three stimulus types (faces, scenes, or words) in electrode signals analyzed in different brain regions.

Outcome measures

Measure	Theta n=1 number of electrodes 3-7 Hz	Alpha n=2 number of electrodes 8-12 Hz	Beta n=1 number of electrodes 13-20 Hz	Gamma 30-60 Hz (low); 60-200 Hz (high)
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Scenes - Increase	0 number of electrodes	2 number of electrodes	1 number of electrodes	—
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Faces - Decrease	1 number of electrodes	1 number of electrodes	0 number of electrodes	—
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Faces - Increase	0 number of electrodes	1 number of electrodes	1 number of electrodes	—
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Scenes - Decrease	1 number of electrodes	0 number of electrodes	0 number of electrodes	—
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Words - Decrease	1 number of electrodes	0 number of electrodes	1 number of electrodes	—
Qualitative Measure: Working Memory Delay Period Phase-amplitude Coupling Reported as Direction (Increase/Decrease) for Region and Stimulus Type Words - Increase	0 number of electrodes	2 number of electrodes	0 number of electrodes	—

PRIMARY outcome

Timeframe: Twenty minutes

Population: Experiment was not conducted, so no data available.

Phase-amplitude coupling refers to the synchrony between low frequency oscillations and bursts of high-frequency signal, which is interpreted as a proxy for neuronal firing. The primary outcome measure is whether the level of phase-amplitude coupling in tissue representing a region of space that is irrelevant for an entire block of trials will change in a manner that mirrors the dynamic changes expected for each trial's uncued location, or whether it will be insensitive to shifts of attention that are, by definition, never relevant for that tissue over the course of that block of trials.

Outcome measures

Outcome data not reported

Adverse Events

Experimental Arm

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Brad Postle, PhD

University of Wisconsin - Madison

Phone: 608-262-4330

Email: postle@wisc.edu

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place