Study of the Role of Top-down Processes in Neuronal Reorganization and Recovery From Sensory Loss: an Exploratory Behavioral and Electroencephalographic Study in Cochlear-supported Deaf Patients

Inclusion Criteria: For cochlear implant patients: * Adult patients * Profound bilateral hearing loss requiring a first cochlear implant * Normal cochlear anatomy (confirmed by preoperative imaging) * Full insertion of the cochlear electrode array planned * Acceptance of the protocol and signing of the informed consent form * Enrollment in a social security or equivalent plan For young patients with normal hearing: * Adult patients aged 18 to 40 * Normal and symmetrical hearing * Acceptance of the protocol and signature of the informed consent form * Affiliation with a social security scheme or equivalent For older patients with normal hearing: * Patients over 50 years of age, matched by gender and age (+/- 2 years) with the cochlear implant patient group * Normal and symmetrical hearing, with hearing thresholds \< 20 dB HL at 2 kHz and \< 40 dB HL at 4 kHz * Acceptance of the protocol and signature of the informed consent form * Affiliation with a social security scheme or equivalent For experienced cochlear implant recipients: * Adult patients. * Unilateral cochlear implant activated for 1 year or more. * Disyllabic word recognition score at 60 dB in free field of 70% or higher. * Acceptance of the protocol and signature of the informed consent form. * Affiliation with a social security plan or equivalent. For severely deaf patients fitted with hearing aids: * Adult patients. * Severe bilateral hearing loss. * Rehabilitation with one or two optimally fitted hearing aids. * Acceptance of the protocol and signing of the informed consent form. * Enrollment in a social security or equivalent health insurance plan. Exclusion Criteria: * History of associated neurological pathology * Etiologies with unfavorable prognoses, such as recurrent chronic otitis media: These conditions are associated with a poor prognosis due to chronic inflammation that can affect the cochlea * Duration of profound bilateral deafness exceeding 5 years (worse prognosis) * Contraindications to EEG or other neurophysiological examinations within the study (for all groups) * Cognitive impairment confirmed by the MOCA test for the cochlear implant patient group and the group of elderly subjects with normal hearing * Use of psychotropic medications that may interfere with the results of cognitive or neurological tests * History of epilepsy or other major neurological disorders * Pregnancy or breastfeeding * Participation in another interventional research protocol or one that impacts the criteria studied in this project * Individuals under legal guardianship (guardianship, tutorship, curatorship, institutionalized, or under a future protection mandate)