Induction of an illusory shadow person

Area of Science:

• Neuroscience
• Psychology
• Neurology

Background:

• The sensation of a nearby presence is reported by patients and healthy individuals.
• The neural mechanisms underlying this illusory feeling remain unclear.
• This phenomenon is associated with psychiatric and neurological conditions.

Purpose of the Study:

• To investigate the brain mechanisms behind the illusory sensation of a presence.
• To determine if focal electrical stimulation can induce this feeling.
• To explore the role of the temporoparietal junction in this perception.

Main Methods:

• Focal electrical stimulation of the left temporoparietal junction in a patient undergoing epilepsy evaluation.
• Repeated induction of the illusory presence sensation.
• Correlation of the sensation with the patient's body position and posture changes.

Main Results:

• Electrical stimulation of the left temporoparietal junction reliably induced the sensation of a "shadow" or presence.
• The illusory presence appeared to track the patient's body movements.
• This suggests a link between temporoparietal junction function and the sense of self/presence.

Conclusions:

• The left temporoparietal junction is critically involved in the multisensory processing of body and self.
• Disturbances in this region may lead to the illusory perception of a presence.
• This finding offers insights into the neural basis of subjective experience and presence hallucinations.