You're Not My Momma: Capgras Delusion

In a traffic accident, David Silvera was thrown from his car and landed on his head. He lay in a coma five weeks. When he awakened he discovered he lost the use of his right arm but felt he remained intact mentally. He kept his intelligence. He was not psychotic, not emotionally disturbed. He read the newspaper with interest and retained his curiosity about the world.

But then he started telling his mother she was an imposter, not his real mom. The same went for his father, who was no longer his real dad. It didn't stop there. The house he lived in was like his parents--just a good imitation of the real one. Not only that, David was not really David. He sometimes became the other David. He was his own imposter.

The injury to David's brain had brought on a very rare condition called Capgras Delusion.

His mother said she was cooking dinner, when David told her, "You know, that lady who comes in the morning she cooks much better than you." He'd say, "It's that lady. I like that lady very much." The other lady was his mother, not this woman.

He said to his father, "You know I'm sure you would like to meet this guy. He's so much like you, but he drives better. He doesn't go so fast."

His parents became tired of hearing David say, "You're not my dad; you're my dad. You're not my mother; you're my mother." They decided, "Okay, you go downstairs, call on the phone." On the phone David recognized both of them. He never had the problem.

Not knowing what to make of this bizarre behavior, worried that David might be crazy, his parents consulted V.S. Ramachandran. Ramachandran told them "This shows the patient is not crazy. Why would he be crazy in person but not on the phone? The answer is there's a separate pathway that goes from the auditory cortex—the hearing part of the temporal lobe—to the amygdala, and that pathway was not damaged in David by the car accident. Therefore, when he listens to his father on the phone there is no delusion. This is a lovely example of how you can take a completely bizarre neurological syndrome—maybe from the X-Files of neurology—which no one really understood: a person claiming that his mother is an impostor; and then come up with a very detailed explanation in terms of the known anatomy of the brain, saying, 'Here is where the flaw is'."

As for Capgras Delusion, Ramachandran explained it this way: "Now, what I've suggested is that what's going on in this patient is the message gets to the temporal lobe cortex, so the patient recognizes his mother as being his mother and evokes the appropriate memories. But the message doesn't get to the amygdala, because the fibers going from the temporal cortex to the amygdala into the emotional centers are cut, as a result of the accident. Therefore, there is no emotion. There is no warmth. And he says, "If this is really my mother why is it I'm not experiencing any emotions? There's something not quite right here. Maybe she is some other strange woman pretending to be my mother." More. (Scroll over half-way down)
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