Neuromodulation of Motion Illusions (Vection) (NEUROVEC)

Virtual reality systems or simulators are more and more frequently used in the field of learning but also in motor rehabilitation. One of the key points of the success of these systems is the experience of "presence" which is associated with the capacity of these technologies to develop in the observer, who is static, the sensation of moving in the virtual environment (vection). However, the simulation generates a sensory conflict (an optical flow specifying self-motion and vestibular stimuli specifying body immobility). This conflict influences the temporal characteristics of the vection and consequently modifies the way users act in their virtual environment. Thus, contrary to a real situation, vection does not occur instantaneously with the appearance of a visual movement. Moreover, the visual stimulus often generates alternating periods of perception of movement of the environment and of oneself (bistable perception) which can lead to "simulator sickness", a disabling situation for the user. Thus, as vection is an essential element to allow an "optimal transfer of learning" from the simulator to reality, it may be important to promote its emergence while limiting its bistability. The aim of this project is to study the inhibitory or facilitative modulation of the emergence of the vection phenomenon by the use of non-invasive cortical stimulation techniques (transcranial electrical stimulation (tES), transcranial alternative current stimulation (tACS), and repeated transcranial magnetic stimulation (rTMS)).

The modulations of the vection phenomenon will then be studied over two sessions of 1h30, separated by a minimum of 3 to a maximum of 15 days (the first session will be performed following the MRI). Each session will include: the installation of an EEG headset and the parameterization of the stimulation (30 min), then a phase of recording of the vection with neuromodulation (1h) according to 2 experimental conditions: Experiment 1: recording of vection at rest (20 min), then during and after neurostimulation by tES (20 min). Active and sham (placebo) stimulation will be tested separately during the two sessions (counterbalanced order). Experiment 2: recording of vection during neuromodulation by rTMS triggered in real time (1h). Triggering will be based on behavioral response (experiment 2a) or oscillatory activity detection (experiment 2b). Active and sham (placebo) stimulation will be tested in both sessions (randomized order).

The modulations of the vection phenomenon will then be studied over two sessions of 1h30, separated by a minimum of 3 to a maximum of 15 days (the first session will be performed following the MRI). Each session will include: the installation of an EEG headset and the parameterization of the stimulation (30 min), then a phase of recording of the vection with neuromodulation (1h) according to 2 experimental conditions: Experiment 1: recording of vection at rest (20 min), then during and after neurostimulation by tES (20 min). Active and sham (placebo) stimulation will be tested separately during the two sessions (counterbalanced order). Experiment 2: recording of vection during neuromodulation by rTMS triggered in real time (1h). Triggering will be based on behavioral response (experiment 2a) or oscillatory activity detection (experiment 2b). Active and sham (placebo) stimulation will be tested in both sessions (randomized order).

The modulations of the vection phenomenon will then be studied over two sessions of 1h30, separated by a minimum of 3 to a maximum of 15 days (the first session will be performed following the MRI). Each session will include: the installation of an EEG headset and the parameterization of the stimulation (30 min), then a phase of recording of the vection with neuromodulation (1h) according to 2 experimental conditions: Experiment 1: recording of vection at rest (20 min), then during and after neurostimulation by tES (20 min). Active and sham (placebo) stimulation will be tested separately during the two sessions (counterbalanced order). Experiment 2: recording of vection during neuromodulation by rTMS triggered in real time (1h). Triggering will be based on behavioral response (experiment 2a) or oscillatory activity detection (experiment 2b). Active and sham (placebo) stimulation will be tested in both sessions (randomized order).

Frequency of vection episodes during a period of visual stimulation before and after neurostimulation (%).

Perceived total time experiencing vection during visual stimulation before and after neurostimulation (s).

Inclusion Criteria: Healthy subjects aged 18 to 40 years Right-handed subjects Signed informed consent, Medical examination performed prior to participation in the research, Affiliation to or beneficiary of a social security plan Exclusion Criteria: Contraindications (CI) to the practice of MRI, EEG, TMS & tES Existence of a severe general condition: cardiac, respiratory, hematological, renal, hepatic, cancerous, Regular use of anxiolytics, sedatives, antidepressants, neuroleptics, Characterized psychiatric pathology, Ingestion of alcohol before the examination, Pregnant, parturient or breastfeeding women Person deprived of liberty by judicial or administrative decision, person under a legal protection measure (under guardianship or curators) Participation in other interventional research protocols in progress with an exclusion period or in the previous week Subject who would receive more than 4500 euros of compensation due to his participation in other research involving the human person in the 12 months preceding this study