Stimulating the brain's left temporoparietal junction causes people to perceive copies of themselves in the room!
Many people from psychiatric and neurologic patients to healthy subjects have described having a strange sensation that someone is near when no one is actually there. It isn’t known how the illusion is triggered by the brain. In an experiment of a patient undergoing presurgical evaluation for epilepsy treatment, some answers were found.
By applying focal electrical stimulation, of the left temporoparietal junction, the illusion of a person closely shadowed changes in the in the patient’s body position and posture. It’s possible that it was caused by a multisensory processing of body and self at the temporoparietal junction.
The temporoparietal junction is where the temporal lobe and the parietal lobe of the brain intersect. The temporal lobe is located on both sides of the brain and is involved in the auditory perception of the brain. It is also key in the semantics of speech and vision.
The parietal lobe is home of sensory information from different modalities, particularly determining spatial sense and navigation. The perception of having copies of you is sort of a déjà vu effect.