What is the capacity of the human brain? What would a reasonable estimate be of the data capacity of the human brain expressed in bytes?
Paul Reber, professor of psychology at Northwestern University, stated that


  The human brain consists of about one billion neurons. Each neuron forms about 1,000 connections to other neurons, amounting to more than a trillion connections. If each neuron could only help store a single memory, running out of space would be a problem. You might have only a few gigabytes of storage space, similar to the space in an iPod or a USB flash drive. 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 petabytes.


1PB = 1,000,000,000,000,000 B = 1015 bytes = 1000 TB (terabytes).1TB = 1,000,000,000,000 bytes = 1012 bytes = 1000 GB (gigabytes). So2.5PB = 2.5 million gigabytes


  For comparison, if your brain worked like a digital video recorder in a television, 2.5 petabytes would be enough to hold three million hours of TV shows. You would have to leave the TV running continuously for more than 300 years to use up all that storage.


The same article states that although it is stated that the brain is capable of storing around 2.5PB of information,


  The brain’s exact storage capacity for memories is difficult to calculate. First, we do not know how to measure the size of a memory. Second, certain memories involve more details and thus take up more space; other memories are forgotten and thus free up space. Additionally, some information is just not worth remembering in the first place.