" Mr. Osborne , may I be excused ? My brain is full, " a student with a particularly small head teacher asks her classroom classic Far Side comic by Gary Larson . The deadpan answer to this question would be , " No, your brain is almost certainly not perfect. " Although there must be a physical limit to how many memories we can store , it is very large . We do not have to worry about running out of space in our lifetime.
The human brain consists of about 1000000000 neurons . Each neuron generates 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 may have only a few gigabytes of storage space , such as 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 memory storage capacity to something closer to around 2.5 petabytes ( or a 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 want to leave the TV running continuously for more than 300 years to use up all that storage .
The brain 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 more space : other memories are forgotten and thus free space . In addition , some information is not only worth remembering in the first place .
This is good news because our brain can keep up as we seek new experiences over our lifetime . If human life span is significantly extended , could we fill our brains ? I'm not sure. Ask me again in 100 years .