Déjà vu explained, no spirits or souls needed

Not that I have thought that a non-materialist explanation was needed, but now we know it isn’t. Memory parallelisms in the hippocampus, a structure deep within our brains, explains the issue.

Most neuroscientists and neuropsychologists have thought for some time that some brain mechanism was the cause of déjà vu, but their explanatory accounts failed. Some said it was a slight difference in firing, or signals recognition, between one eye and another.

But now, we know what’s actually happening.

U.S. researchers have identified the part of the brain responsible for this sensation, and they think it may lead to new treatments for memory-related problems.

They said neurons in a memory center of the brain called the hippocampus make a mental map of new places and experiences, then store them away for future use.

But when two experiences begin to seem very much alike, these mental maps overlap and start to blur.

“Deja vu occurs when this ability is challenged,” said Susumu Tonegawa, a professor of biology and neuroscience at the Massachusetts Institute of Technology in Cambridge, whose work appears in the journal Science.

The scientists tested mice with mutant genes that affected one part of the hippocampus, and saw them unable to distinguish between two similar but not identical cages. They noticed differences in brain activity from healthy mice and worked from there.

It makes more sense to me than some older explanations. The hippocampus is involved with the consolidation of episodic memory into long-term memory. Given the great variety of human memories, the malleability of memory, and the emotional overtones of many memories, it’s a wonder that déjà vu episodes don’t happen more in normal, everyday people’s lives.