Causal Role of the Aperiodic Signal for Working Memory (TRAS)

January 9, 2026 updated by: Justin Riddle, Florida State University
Working memory (WM) is the ability to hold relevant information in mind in the absence of sensory input. The capacity for WM is a foundation for cognitive control and higher cognitive function more broadly. Previous research demonstrated that during the delay period of WM tasks, oscillatory electrical activity in the prefrontal cortex in the theta-frequency band (4-8 Hz) increased in amplitude. However, other groups found that the slope of the aperiodic signal in the brain was positively correlated with individual differences in WM capacity. Since low-frequency power and a steeper slope of the aperiodic signal are confounded in many analyses, it is not clear whether the slope of the aperiodic signal or the amplitude of low-frequency oscillations underlie WM capacity. With many studies investigating the causal role of theta oscillations in WM, the purpose of this project is to investigate the role of the aperiodic signal in WM performance.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

The experiment comprises two experimental sessions. The first session serves as a baseline session where electroencephalography (EEG) is recorded during working memory (WM) task performance. The difficulty of the task is titrated to the individual participant and they are familiarized with the task. In the second session, the participant receives each type of transcranial random aperiodic stimulation (tRAS): steep-tRAS, flat-tRAS, sham-tRAS. Stimulation is delivered in one of these three waveforms for each block while the participant performs the WM task. The type of stimulation that is received is balanced, randomized, and intermixed by block. This study is double-blinded such that the participant and the researcher are not aware of what type of stimulation is being delivered. Each block is approximately 5 minutes and twelve total blocks are collected with stimulation. The type of tRAS for that block (steep-tRAS, flat-tRAS, or sham-tRAS) is started just prior to the beginning of the task block and ramps down at the end of the task block. For each task block, the tRAS takes 15 seconds to ramp up at the beginning and 15 seconds to ramp down at the conclusion of the task block. In total, the participant receives approximately 60 minutes of stimulation, which is approximately 20 minutes of each type of stimulation. Following each task block, participants stare at a fixation cross and relax without stimulation. This "resting-state" EEG recording is used to assess the aftereffects of tRAS on brain activity. The first session will take 2 hours to complete and the second session will take 3 hours to complete.

Study Type

Interventional

Enrollment (Estimated)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Justin Riddle, PhD
  • Phone Number: 850-645-2389
  • Email: jriddle@fsu.edu

Study Contact Backup

Study Locations

  • United States
    • Florida
      • Tallahassee, Florida, United States, 32306
        • Recruiting
        • Florida State University
        • Contact:
        • Principal Investigator:
          • Justin Riddle, PhD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Between the ages of 18 and 35
  • Able to provide informed consent
  • Normal or corrected-to-normal vision
  • Willing to comply with all study procedures and be available for the duration of the study
  • Ability to speak, read and understand English without a translator
  • Not color-blind

Exclusion Criteria:

  • ADHD/ADD (currently under treatment)
  • Neurological disorder and conditions
  • Medical or neurological illness or treatment for a medical disorder that could interfere with study participation, e.g., unstable cardiac disease, HIV/AIDS, malignancy, liver or renal impairment
  • Prior brain surgery
  • Any brain devices/implants, including cochlear implants and aneurysm clips
  • History of traumatic brain injury
  • (For females) Pregnant
  • Anything that, in the opinion of the investigator, would place the participant at increased risk or preclude the participant's full compliance with or completion of the study
  • Current use of medications know to produce specific EEG activity known to disrupt interpretations of the findings including but not limited to: benzodiazepines, antipsychotics, antiepileptics and central nervous system stimulants

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Steep-tRAS,
Transcranial random aperiodic stimulation (tRAS) delivers 1 milliampere (mA) zero-to-peak amplitude at the target electrodes and 2 mA at the return electrode. The condition of interest, steep-tRAS, mimics a steep slope of the aperiodic signal characterized by greater low relative to high frequency power. Participants receive all three types of stimulation in an intermixed, balanced, and randomized order. There are twelve total blocks of approximately five minutes of stimulation with four blocks of each type of stimulation.
Device: Steep-tRAS
Stimulation will be delivered via the NeuroConn Direct Current Stimulator Plus Multiple Channels, an investigational electrical non-invasive brain stimulation device that is being used for foundational neuroscience and translational research.
Active Comparator: Flat-tRAS
Transcranial random aperiodic stimulation (tRAS) delivers 1 milliampere (mA) zero-to-peak amplitude at the target electrodes and 2 mA at the return electrode. The active control, flat-tRAS, mimics a flat slope aperiodic signal characterized by greater high relative to low frequency power. Participants receive all three types of stimulation in an intermixed, balanced, and randomized order. There are twelve total blocks of approximately five minutes of stimulation with four blocks of each type of stimulation.
Device: Flat-tRAS
Stimulation will be delivered via the NeuroConn Direct Current Stimulator Plus Multiple Channels, an investigational electrical non-invasive brain stimulation device that is being used for foundational neuroscience and translational research.
Sham Comparator: Sham-tRAS
Transcranial random aperiodic stimulation (tRAS) delivers 1 milliampere (mA) zero-to-peak amplitude at the target electrodes and 2 mA at the return electrode. For active sham stimulation, steep-tRAS or flat-tRAS is delivered for only 15 seconds at the beginning and end of the block. This mimics the skin sensations (e.g., itching, burning, tingling) to assist with blinding the participant. Participants receive all three types of stimulation in an intermixed, balanced, and randomized order. There are twelve total blocks of approximately five minutes of stimulation with four blocks of each type of stimulation.
Device: Sham-tRAS
Stimulation will be delivered via the NeuroConn Direct Current Stimulator Plus Multiple Channels, an investigational electrical non-invasive brain stimulation device that is being used for foundational neuroscience and translational research.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in number of remembered items
Time Frame: 3 hours
The number of remembered items, often referred to as working memory capacity, is calculated as the number of items to be remembered multiplied by the number of items successfully remembered divided by the number of total trials. The range of values is 0 to 7 where a larger number denotes a greater number of items that were remembered.
3 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in slope of the power spectrum of the EEG
Time Frame: 3 hours
The power spectrum of an electrical brain recording is calculated by performing a Fourier transform on the time signal. The slope is calculated as the general trend of this background signal.
3 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Florida State University

Investigators

  • Principal Investigator: Justin Riddle, PhD, Florida State University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 25, 2024

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

November 7, 2023

First Submitted That Met QC Criteria

November 9, 2023

First Posted (Actual)

November 13, 2023

Study Record Updates

Last Update Posted (Estimated)

January 12, 2026

Last Update Submitted That Met QC Criteria

January 9, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • STUDY00004479

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Deidentified individual data that supports the results will be shared beginning 9 to 36 months following publication provided the investigator who proposes to use the data has approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with FSU.

IPD Sharing Time Frame

9 to 36 months following publication

IPD Sharing Access Criteria

Deidentified individual data that supports the results will be shared provided the investigator who proposes to use the data has approval from an IRB, IEC, or REB and an executed data use/sharing agreement with FSU.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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