Human brain can store 4.7 billion books - ten times more than originally thought

The human brain has a capacity that is ten times greater than first thought and can retain 4.7 billion books, scientists have discovered.

This is according to US scientists who have measured the storage capacity of synapses - the brain connections that are responsible for storing memories.

They discovered that, on average, one synapse can hold roughly 4.7 bits of information. This means that the human brain has a capacity of one petabyte, or 1,000,000,000,000,000 bytes.

One petabyte is the same as 20 million four-drawer filing cabinets filled with text,13.3 years of HD-TV recordings, 4.7 billion books or 670 million web pages.

However, this is only the total amount of information that the relevant part of the brain could theoretically carry at any one moment. Its actual archive of memories would be a lot smaller.

Nevertheless, Professor Terry Sejnowski, of the Salk Institute for Biological Studies, in California, said the discovery is a “real bombshell in the field of neuroscience”.

“We discovered the key to unlocking the design principle for how hippocampal neurons function with low energy but high computation power,” he said.

“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.”

The paper was published in eLife.