In a finding they're calling a "real bombshell in the field of neuroscience," researchers have uncovered evidence that the human brain's memory capacity is an order of magnitude greater than previously thought.

"Our new measurements of the brain's memory capacity increase conservative estimates by a factor of 10 to at least a petabyte," Dr. Terry Sejnowski, a professor at the Salk Institute in La Jolla, California, and co-senior author of a paper describing the research, said in a written statement.

In other words, the human brain may be able to store one petabyte of data, which is 1 quadrillion bytes. That's enough memory to store 13.3 years of high-definition video.

The finding, published recently in the journal eLife, is considered preliminary and must be confirmed by future research. But it constitutes a significant advance in our understanding of neuroanatomy and could prove to be a step toward the creation of a complete "wiring diagram" of the human brain, Sejnowsky told The Huffington Post.

In addition, the finding could point the way to a new generation of computers that combine enormous processing power with low energy consumption. Such "probabilistic" computing devices -- so called because they process data in a way that is more intuitive than conventional computers -- are considered a game-changer for applications ranging from translation to machine vision.

We have to think of the brain not as an old grandfather clock but as a high-precision watch."

Sejnowski and his collaborators at Salk and the University of Texas at Austin made the discovery as part of a detailed anatomical examination and subsequent 3D computer reconstruction of the cells within a tiny portion of tissue from the brain of a rat.

The reconstruction showed that the variation in the sizes of the synapses within the sample -- the tiny gaps between brain cells that are known to be key to memory formation and storage -- was far smaller than previous research had suggested. In fact, the synapses varied in size by only about 8 percent. (Synapses in the rat brain are believed to be similar to those in the human brain.)

"No one thought it would be such a small difference," Dr. Tom Bartol, a staff scientist at the institute and one of the researchers, said in the statement. "This was a curveball from nature."

When the researchers plugged the 8-percent figure into their computer model of the brain, they determined that there must be more than two dozen discrete sizes of synapse rather than just a few. That bigger number, in turn, meant that the synapses must be able to store far more information than anyone knew.

Having more "bits" per synapse is a little like a high-definition TV having more bits per pixel than a conventional TV, Sejnowski said, adding that, "We think the brain is high-resolution now."

Or, offering up another metaphor, he said, "We have to think of the brain not as an old grandfather clock but as a high-precision watch."

Some scientists think that the human brain is capable of storing even more information. The brain's true memory capacity may be even greater -- as much as 3 to 5 petabytes, Dr. Paul Reber, director of the Brain, Behavior, & Cognition program in the psychology department at Northwestern University, told the San Diego Union-Tribune.

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