Enhancing Letter-Speech Sound Learning and Reading Network Activation With Transcranial Electrical Stimulation (LexiStim)

May 19, 2026 updated by: Silvia Brem

Transcranial Electrical Stimulation and the Reading Brain: Toward Novel Interventions for Reading Impairments

This study investigates the effects of transcranial electrical stimulation (tES) on the brain and its potential to enhance reading-related learning. Adult participants with a range of reading abilities will receive transcranial random noise stimulation (tRNS) while they perform an artificial orthography learning task. This task simulates letter-speech sound learning, an important first step during reading acquisition known to be impaired in individuals with developmental dyslexia. The effects of the intervention will be assessed using both behavioral measures and functional magnetic resonance imaging (fMRI).

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This study investigates the effects of transcranial electrical stimulation (tES) on the brain and its potential to enhance reading-related learning. The aim is to identify novel techniques for treating developmental dyslexia, which is a common learning disorder that occurs in childhood and can persist into adulthood. Typically, standard therapy for dyslexia consists of specific reading exercises; however, such training often does not fully remediate the difficulties.

This study, therefore, evaluates how transcranial electrical stimulation may be applied to support learning and ultimately reading. During the stimulation, participants perform an artificial orthography learning task simulating letter-speech sound learning. Whereas previous tES reading studies have focused primarily on behavioral outcomes, the present study additionally measures brain activity using fMRI to elucidate how tES affects neural processing and how these effects may relate to reading abilities.

The knowledge gained from this project is intended to support the future development of transcranial electrical stimulation as an intervention for adults and children with developmental dyslexia.

Study Type

Interventional

Enrollment (Estimated)

60

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

Study Locations

  • Switzerland
      • Zurich, Switzerland
        • Recruiting
        • University Hospital of Psychiatry

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:

  • Age 18-35
  • All genders
  • Written informed consent by the participant
  • German speaking (native)
  • Right-handed

Exclusion Criteria:

  • Diagnoses of neurological disorders, intellectual disabilities, or psychiatric disorders (We do not exclude participants with common comorbidities of dyslexia, specifically dyscalculia, Attention Deficit/Hyperactivity Disorder, or Autism Spectrum Disorders)
  • History of any acquired brain damage or evidence of fetal alcohol syndrome
  • Hearing problems and vision problems that cannot be corrected
  • Inability to follow procedures or understand the instructions given in (Swiss-)German
  • Current use of psychoactive medications or substances, or a history of substance abuse that may affect brain function, performance or MRI signal quality
  • A nonverbal IQ < 80
  • Having previously participated in a transcranial electrical stimulation study
  • Knowledge to read or write in a language using foreign letters (i.e., different from the Latin alphabet)
  • Contraindications to brain stimulation or MRI, such as: History of epilepsy or severe migraine; Skull breach such as craniotomy; Wearing neurostimulators or cardiac pacemakers; Wearing hearing aid devices or cochlear implants, which are not MR safe; Having metal pieces in their body (e.g., piercings that cannot be removed and contain metal, screws or plates from surgical operations, wounds from metal splinters or similar); Claustrophobia or problems lying in the scanner (e.g., pain, anxiety); Previous surgery on the head or heart; Being pregnant (a pregnancy test will be conducted at the MR center before the measurement if a female participant suspects she might be pregnant or is uncertain about her pregnancy status according to the Swiss Ethics Leitlinie:

https://swissethics.ch/assets/pos_papiere_leitfaden/20110906_kek_mri.pdf); Having problems lying still (strong cold, tremor, etc.); Wearing non-removable dental braces

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: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Real Stimulation
Participants will receive transcranial random noise stimulation (tRNS) applied to the left superior temporal gyrus.
Other: Transcranial random noise stimulation
Participants will receive high-frequency tRNS (max. 1.5 mA) applied to the left superior temporal gyrus. A high-definition setup (3x1 electrodes) will be used to achieve more focal stimulation. Stimulation will be applied during an artificial orthography learning task with simultaneous fMRI acquisition.
Sham Comparator: Sham Stimulation
Participants in this group will serve as the control condition. The setup will be identical to the active stimulation group, but stimulation will be sham, such that no electrical current will be applied for the duration of the session.
Other: Sham Stimulation
Participants will also have electrodes placed on their scalp. The setup is programmed to induce a short ramp-up of the chosen electrical current followed by a ramp-down at the beginning and at the end of the stimulation. In between, no current will be applied. Sham stimulation will be applied during an artificial orthography learning task with simultaneous fMRI acquisition.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Performance in the artificial orthography learning task
Time Frame: At second session, up to 8 weeks after baseline
Performance on the artificial orthography learning task and the artificial orthography reading fluency test will be compared between the stimulation and sham groups.
At second session, up to 8 weeks after baseline
fMRI activation and connectivity during print processing
Time Frame: At baseline (Session 1) and at second session, up to 8 weeks after baseline
fMRI activation and connectivity of the posterior superior temporal gyrus and other regions of the reading and audiovisual learning networks will be compared before, during and after transcranial electrical stimulation (tES). The fMRI tasks performed in the second session include artificial orthography learning and explicit print processing (lexical decision task), whereas implicit print processing (one-back task) is performed both at baseline and in the second session. These changes in activation and connectivity will be compared between the stimulation group and the sham group.
At baseline (Session 1) and at second session, up to 8 weeks after baseline

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
fMRI brain activation and connectivity in further fMRI tasks: audiovisual processing and naturalistic movie watching
Time Frame: At baseline (Session 1) and at second session, up to 8 weeks after baseline
Brain activation and connectivity during further fMRI tasks, namely an audiovisual localizer task and a movie-watching paradigm, will be investigated and compared between the two groups. The audiovisual localizer task focuses on brain activation in reading and audiovisual processing regions, and the movie-watching paradigm on connectivity within the resting-state networks.
At baseline (Session 1) and at second session, up to 8 weeks after baseline
Reading and reading-related behavioral measures
Time Frame: At baseline (Session 1) and at second session, up to 8 weeks after baseline
Reading and reading-related tasks, such as word and pseudoword reading, will be performed before and after tES to provide a behavioral estimate of reading skills.
At baseline (Session 1) and at second session, up to 8 weeks after baseline
Performance in further cognitive tasks
Time Frame: At baseline (Session 1) and at second session, up to 8 weeks after baseline
The performance in further cognitive tasks (working memory, attention, rapid automatized naming) will be compared before and after tES.
At baseline (Session 1) and at second session, up to 8 weeks after baseline

Collaborators and Investigators

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

Sponsor

Silvia Brem

Collaborators

Swiss National Science Foundation

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)

April 23, 2026

Primary Completion (Estimated)

June 1, 2027

Study Completion (Estimated)

June 1, 2027

Study Registration Dates

First Submitted

April 9, 2026

First Submitted That Met QC Criteria

April 16, 2026

First Posted (Actual)

April 22, 2026

Study Record Updates

Last Update Posted (Actual)

May 22, 2026

Last Update Submitted That Met QC Criteria

May 19, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • BASEC2025-01540

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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