Sept. 20, 2006 -- Stimulating a certain spot in the brain with electricity may make people feel like a shadow person is hovering nearby.
Doctors in Switzerland documented the startling sensation in a 22-year-old woman with no history of psychiatric problems.
The researchers stumbled upon the discovery while evaluating the woman for epilepsyepilepsy surgery.
During the checkup, the doctors electrically stimulated the left temporoparietal junction in the woman's brain.
Out of the blue, the woman reported having "the impression that someone was behind her," write Shahar Arzy, MD, and colleagues in Nature. Arzy works at the Laboratory of Cognitive Neuroscience at the Ecole Polytechnique Federale de Lausanne in Lausanne, Switzerland.
'He Is Behind Me'
The woman described the shadow person as young, silent, and mirroring her position as she lay on her back. "He is behind me, almost at my body, but I do not feel it," she said, according to the doctors.
Again, the woman sensed the shadow presence. This time she said the man was sitting behind her and had his arms around her.
Lastly, the woman sat up, holding a card in her right hand, for another brain test that involved stimulating the same brain area. She once more sensed the shadow person.
"He wants to take the card. He doesn't want me to read," the woman reportedly said.
Of course, there was no such person present during the tests. But the shadow person apparently seemed very real to the woman.
"The sensation of a presence, as reported by this patient, has been described by people with psychiatric and neurological disorders," the researchers write.
The left temporoparietal junction may play a role in those disorders, judging by the woman's experience, note Arzy and colleagues.