martedì 26 marzo 2013

A Single Brain Cell Stores a Single Concept

Scientifica American, February 2013.
Each concept — each person or thing in our everyday experience — may have a set of corresponding neurons assigned to it.
Once a brilliant Russian Neurosurgeon named Akakhi Akakhievitch had a patient who wanted to forget his overbearing, impossible mother......
Eager to oblige, Akakhievitch opened up the patient's brain and, one by one, ablated several thousand neurons, each of which related to the concept of his mother. When the patient woke up from anesthesia, he had lost all notion of his mother. All memories of her, good and bad, were gone. Jubilant with his success, Akakhievitch turned his attention to the next endeavor — the search for cells linked to the memory of “grandmother.”

For decades neuroscientists have debated how memories are stored. That debate continues today, with competing theoriesone of which suggests that single neurons hold the recollection, say, of your grandmother or of a famous movie star.
The alternative theory asserts that each memory is distributed across many millions of neurons. A number of recent experiments during brain surgeries provide evidence that relatively small sets of neurons in specific regions are involved with the encoding of memories.
At the same time, these small groupings of cells may represent many instances of one thing; a visual image of Grandma's face or her entire body — even a front and side view or the voice of a Hollywood star such as Jennifer Aniston.

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