Saturday, September 06, 2008

Neuroscience: Individual brain cells spotted in act of retrieving memories

Benedict Carey reports in "For the Brain, Remembering Is Like Reliving" (Los Angeles Times, September 4, 2008) that

Scientists have for the first time recorded individual brain cells in the act of summoning a spontaneous memory, revealing not only where a remembered experience is registered but also, in part, how the brain is able to recreate it.

The recordings, taken from the brains of epilepsy patients being prepared for surgery, demonstrate that these spontaneous memories reside in some of the same neurons that fired most furiously when the recalled event had been experienced. Researchers had long theorized as much but until now had only indirect evidence.

Experts said the study had all but closed the case: For the brain, remembering is a lot like doing (at least in the short term, as the research says nothing about more distant memories).
Of course, they are not saying that the memories are in a single neuron:

Dr. Fried said in a phone interview that the single neurons recorded firing most furiously during the film clips were not acting on their own; they were, like all such cells, part of a circuit responding to the videos, including thousands, perhaps millions, of other cells.

[ ... ]

Single-cell recordings cannot capture the entire array of circuitry involved in memory, which may be widely distributed beyond the hippocampus area, experts said. And as time passes, memories are consolidated, submerged, perhaps retooled and often entirely reshaped when retrieved later.

Yes indeed. Memory, especially when we are old and have a lot of it, is always being edited.

These results support the approach that Mario Beauregard and Vincent Paquette were working with when they asked Carmelite nuns to recall mystical experiences, as reported in The Spiritual Brain. The nuns' recollections would activate the same circuits that were active when the experience occurred.

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