Enhancing Speech Intelligibility Using Transcranial Alternating Current Stimulation (tACS)

Summary

This study contributes to fundamental research investigating the role of the articulatory-motor integration and cerebro-acoustic coherence in speech comprehension. In a series of experiments non-invasive brain stimulation (NIBS) techniques including transcranial electric stimulation with alternating current waveforms (tACS) and transcranial magnetic stimulation (TMS) will be applied to the left ventral motor cortex (vMC) to test the contribution of this area to speech comprehension under challenging listening situations. As long as the exclusion criteria for TMS and tACS are strictly considered, only very minimal risks and no long-term effects are expected.

There are no known risks associated with NIBS and pregnancy; however, since risks cannot be completely excluded, pregnant women will be excluded from participation. If a female participant is uncertain whether she is pregnant, she will be provided with a pregnancy test at no cost.

Conditions

• Electric Stimulation Therapy
• Transcranial Magnetic Stimulation

Interventions

DEVICE

Transcranial alternating current stimulation (tACS)

The main study intervention is tACS stimulation. TACS is a non-invasive brain stimulation (NIBS) techniques that belong to the class of low current transcranial electric stimulation. In contrast to the better known transcranial direct current stimulation (tDCS), the tACS current is not constant, but alternates with a certain frequency. The aim of the tACS stimulation is to enhance degraded speech comprehension in healthy individuals. TACS stimulation will be applied over the left ventral motor cortex, with a current intensity of 2mA (peak-to-peak) The arm will be compared to the tACS sham stimulation condition.

DEVICE

Transcranial magnetic stimulation (TMS) induced motor-evoked potentials (MEPs)

TMS is a technique where a transient magnetic field (or "pulse") is used to cause an electric current to flow in a targeted brain area via electromagnetic induction. The pulse causes the rapid and above-threshold depolarisation of cell membranes affected by the current. Therefore, TMS induces a current that elicits action potentials in neurons. MEPs are electrical potentials recorded from a target muscle after TMS stimulation. In experiment 1, so-called articulatory MEPs will be recorded from participants' lip muscle (orbicularis oris). Articulatory MEPs will be recorded by placing two recording electrodes on the right part of orbicularis oris and a reference electrode on the right temple.

Sponsors & Collaborators

• Insel Gruppe AG, University Hospital Bern

  collaborator OTHER

• University of Zurich

  lead OTHER

Principal Investigators

• Alexis Hervais-Adelman, Prof. Dr. · University of Zurich, Institute for Psychology

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

80 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2020-12-01

Primary Completion

2024-02-28

Completion

2024-02-28

Countries

• Switzerland

Study Locations