Hardly a day passes by without some or the other research organization putting out a paper related to neuroscience, or the study of the brain. Many of these findings may seem esoteric to most people. Moreover, most of the experiments are conducted on the brains of animals like rats and monkeys, so the outcome could be different when human brains are tested.

Regardless, such findings do appeal to people who are curious to know exactly how the brain functions. Why are some intelligent and others dumb? Why and how does our small brain consume so much energy? Will computers eventually match the brain's power? Is there something like a left brain or right brain--a myth that may never die despite researchers debunking it periodically? Why do we mine only a fraction, or 10%, of our brain--another popular saying touted mostly by motivational speakers but one that is not backed by scientific evidence?

On 20 July, researchers from the Salk Institute for Biological Studies, US, revealed that the memory capacity of the brain is far higher than common estimates.

Estimates of the human brain's memory capacity vary wildly from 1 to 1,000 terabytes. For the sake of comparison, the 19 million volumes in the US Library of Congress represent about 10 terabytes of data. A byte comprises 8 bits or binary digits (0 or 1). A terabyte (TB) is 1,012 bytes and a petabyte (PB), 1,015 bytes.

In a 1 May 2010 article in the Scientific American, Paul Reber, a professor of psychology at Northwestern University, acknowledged that it is difficult to calculate the brain's exact storage capacity for memories. Yet neurons combine so that each one helps with many memories at a time, exponentially increasing the brain's memory storage capacity to something closer to around 2.5 PB (or a million gigabytes), he said.

Prof. Reber added that if you were to liken your brain to a digital video recorder in a television, 2.5 PB would be enough to hold 3 million hours of TV shows. This implies that you would have to leave the TV running continuously for more than 300 years to use up all that storage.

The Salk scientists say the brain's memory is bigger. "Our new measurements of the brain's memory capacity increase conservative estimates by a factor of 10 to at least a petabyte, in the same ballpark as the World Wide Web," said Terry Sejnowski, a Salk professor and co-senior author of the paper that was published in eLife, a journal that is owned by eLife Sciences Publications Ltd.

Brains are made up of nerve cells, or neurons. The number of neurons is pegged at about 100 billion, though this figure is now believed to be around 86 billion.

The scientists, who built a 3D reconstruction of a rat hippocampus tissue (the memory centre of the brain) for this purpose, also answered a long-standing question on why the brain is so energy-efficient. This, the scientists said in their statement, could help engineers build computers that are incredibly powerful but also conserve energy. This finding is also significant because while the brain may represent only about 2% of the body weight in an average adult, it uses about 20% of the oxygen and, hence, calories consumed by the body.

This, of course, is not the last word on the brain. So watch out for more grey matter sprinkling on this topic.

SMART IMPLANTS

Intelligence, driven by sensors

u Inventor and futurist Ray Kurzweil believes that artificial intelligence (AI) will soon become more powerful than the human brain, though many scientists do not subscribe to this view.

u Neuroscientists at the University of Sussex's Sackler Centre and Brighton and Sussex Medical School in the UK have identified the brain network system that causes us to stumble and stall just when we are least ready for it.

u Implants, developed by scientists at the Washington University School of Medicine in St Louis, and engineers at the University of Illinois at Urbana-Champaign, US, could potentially be used to monitor patients with traumatic brain injuries, but researchers believe they can build similar absorbable sensors to monitor activity in organ systems throughout the body.

uA new programme of the Defense Advanced Research Projects Agency in Virginia, US, aims to develop an implantable neural interface able to provide unprecedented signal resolution and data-transfer bandwidth between the human brain and the digital world. The programme, Neural Engineering System Design, may dramatically enhance research capabilities in neurotechnology and provide a foundation for new therapies.

Cutting Edge is a monthly column that explores the melding of science and technology.

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