One human brain can have two different personalities dwelling in it, according to a new imaging study - and each personality seems to use its own network of nerves to help recall or suppress memories.Alternative personalities are typically developed by children who suffer severe trauma or abuse. The condition, called multiple personality disorder, or dissociative identity disorder, appears to help people cope by cutting off difficult memories, making them seem as if they happened to someone else.A team led by Simone Reinders of Groningen University Hospital in the Netherlands used positron emission tomography to scan the brains of 11 female multiple-personality patients while they listened to autobiographical stories in each of their two personality states.In one persona, patients recognized the traumatic history as their own, and it triggered emotional centres in their brain. In the other personality, they did not consciously recognize the tale as autobiographical, and it fired up a wider brain network including regions involved in self-awareness or consciousness. These regions would not be expected to be active in people with a single personality hearing stories that are not about themselves. "The brain has to actively suppress the traumatic information," says Reinders. She thinks that these additional brain regions stifle the autobiographical memories and erase them from that personality's perceived past.
View: Full Article | Source: Nature
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