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

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.

Inclusion Criteria:

• Having given their written informed consent
• Affiliated with a social security scheme
• French speakers and readers

Exclusion Criteria:

• With contraindication to HD-tDCS stimulation or fMRI
• With a history of or current hearing problems, including tinnitus
• Taking medication (except contraceptives)
• With a history of or current psychiatric diagnosis (DSM-5 criteria)
• First-degree relatives with a diagnosis of schizophrenia spectrum disorder or bipolar disorder (DSM5)
• Have a personal history of neurological disorders or head trauma with loss of consciousness
• With an intellectual disability (Raven's Matrices)
• With developed musical abilities (i.e., regular practice of a musical instrument for at least 10 years with assiduity or at a music school or conservatory)
• Pregnant or nursing
• Being in a period of exclusion and/or having exceeded the annual indemnity ceiling (€4,500) for other clinical research.
• Under guardianship

Participants and experimenters (including tDCS operator) will not be informed about the nature (active or placebo) of the stimulation they will receive.