The study aims at mapping the magnetoencephalographic (MEG) activities induced in normal volunteers by tapping the finger .

Normal healthy (20) volunteers and tetraplegic patients(10) will be submitted to the temporo-spatial mapping of their brain activity, both sensory and motor, induced by a simple behavioral task, consisting on tapping with the finger on a detection pad. This will be done in a light and then dark environment, on a rythm spontaneous and then paced by sound bips. Accelerometric recording will provide the three dimensionnal displacements of the finger as well as the time code.

Brain activity is simultaneously recorded using MEG (306 channels) and EEG (64 channels. Data will be processed by an INPLS algorithm to detect the predictors of activity, their location and time-course.

3D mapping data will be matched with the patient's anatomy provided by 1.5T MRI previously performed.

The aim of the study is to prepare the strategy of implantation of multielectrodes ECoG implants to restore motility in tetraplegic patients in a human BCI protocol currently under development.

Inclusion Criteria:

• Male or Female between 18 and 70 years
• Informed consent
• Benefiting from Social Security
• French or english speaking, to understand study procedure
• Tetraplegic patients : traumatic injury of the cervical spine with retained respiratory autonomy and without associated head injury

Exclusion Criteria:

• Contra-indication to MRI
• Claustrophobia
• Mental disorders
• Pregancy
• All categories of protected persons