NCT05936307

Externalization and Stimulation

Modulation of Auditory Externalization Abilities by Transcranial Stimulation of the Brain Area Specifically Involved

• Status: Unknown
• Phase: N/A
• Study type: Interventional
• Enrollment: 30 (estimated)
• Sponsor: Hôpital le Vinatier · Academic / Other
• Sex: All
• Age: 18 Years – 30 Years
• Healthy volunteers: Accepted

Summary

The distinction between self-generated and external information is impaired in patients with schizophrenia, who are assumed to confuse imagination with real perceptions. To better understand the underlying mechanisms of these abnormalities, the investigator will investigate the brain mechanisms supporting auditory externalization. Auditory externalization is the ability to perceive whether a sound comes from inside or outside oneself. Our study, in healthy participants, will use functional brain imaging to identify the brain areas involved in the externalization of sound sources and to test whether neuromodulation of this area can modify this ability and provide a therapeutic lead in pathological populations

Detailed description

30 healthy participants will be included. The participants will undergo three separate visits. During the first one, the participants will listen to sounds coming from either internal or external sources while undergoing an fMRI session. This will allow us to identify the brain region involved in externalizing abilities with the highest activity. In the second and third visits, this specific region will be targeted by HD-tDCS (a non-invasive high-definition neuromodulation technique whose precision is enhanced by individual data) to modulate its activity and test its causal involvement in externalization processes. Each participant will receive both active and placebo stimulation, with the order counterbalanced. During the stimulation, participants will complete an externalization task, followed by a reality monitoring task and a self-agency task. Additionally, the investigator will gather socio-demographic and psychometric data.

Conditions

• Healthy Participants

Interventions

Type	Name	Description
PROCEDURE	High-definition transcranial direct current (HD-tDCS), active condition	Participants will receive a session of active HD-tDCS at a current intensity of 2 mA for a duration of 25min. The placement of electrodes will be determined to specifically target the brain area that has been identified as being involved in the process of externalization, as evidenced by fMRI. During the stimulation, participants will be engaged in a computer-based externalization task.
PROCEDURE	High-definition transcranial direct current (HD-tDCS), placebo condition	Participants will receive a session of placebo HD-tDCS, which will be delivered following the same procedures as active HD-tDCS but the intensity of the current will be set at 2mA during the 30 first seconds at the beginning of the 25-min period of the stimulation, and equal to 0 mA for the reminding period of stimulation to simulate the tingling sensation often experienced by individuals during active stimulation. The placement of electrodes will be determined to specifically target the brain area that has been identified as being involved in the process of externalization, as evidenced by fMRI. During the stimulation, participants will be engaged in a computer-based externalization task

Timeline

• Start date: 2024-01-16
• Primary completion: 2025-01-16
• Completion: 2025-09-30
• First posted: 2023-07-07
• Last updated: 2024-03-07

Locations

1 site across 1 country: France