The invention relates to an implantable device for optically stimulating the brain of a person or an animal, the device comprising:a light source emitting in the near infrared range anda light guide that is implantable in the brain of a person or an animal, the light guide being provided with a sheath of biocompatible material and having a proximal end for receiving the light emitted by the source, and a distal end for delivering said light to the inside of the brain.
