A latest study suggested that the human brain can hold 10 times more memories than believed earlier. The key to its amazing ability is present in synapses, the neural links accountable for memory storage.

The Salk Institute researchers discovered that each synapse can hold nearly 4.7 bits of information, which means that the human brain has a capacity of one petabyte, or 1,000,000,000,000,000 bytes. It is equal to roughly 20 million four-drawer filing cabinets packed with text.

Terry Sejnowski, Salk professor and co-senior author of the paper, said, “This is a real bombshell in the field of neuroscience...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 the journal eLife.

The discovery of the impressive capability of human brain was done when the scientists were creating a 3D reconstruction of rat hippocampus tissue to use it as a proxy for human brain cells.

When they observed their creation, they found something strange. To understand the finding, one has to understand the basic science of memories.

The patterns of electrical and chemical activity in the brain result into memories and thoughts. An important part of the activity takes place when neurons’ branches intersect at particular junctions, called synapses.

Thereafter, an output 'wire' (axon) from a neuron connects to an input 'wire' (dendrite) of another neuron. Signals travel through the synapse as chemicals known as neurotransmitters, telling the neuron on the receiving end whether to pass an electrical signal to other neurons or not.

A Salk Institute press release mentioned that when the researchers analyzed the 3D reconstruction, they noticed that in a few cases, a single axon from a single neuron formed two synapses that reached out to a single dendrite of another neuron, indicating that the first neuron was apparently transmitting a duplicate message to the neuron at the receiving end.