How do we learn new information? How much memory do we have? How fast is our processor?

The brain has about 100,000,000,000 (billion) neurons, and roughly 50,000,000,000,000 (trillion) connections between individual neurons, or synapses. These neurons are connected by more than 90,000 miles of fibers — more than 7 times the length of the entire U.S. coastline, including Alaska. As learning generally takes place at synapses, the connection points between neurons, the brain has enormous ability to absorb and encode information quickly.
As you can see in this graphic, our brains have about 3,500,000,000,000,000 (quadrillion) bytes for data storage, and a processing speed of about 2,200,000,000 (billion) megaflops or millions of operations per second. Amazingly, it does that with a power consumption of only about 20 watts.

This intricate architecture allows us to absorb and process a great deal of information quickly and efficiently. At these junctions between neurons/synapses, as learning something new takes place, the related synapses change. The more often this same information or function is repeated, the more the synapses change, and the more efficient that linkage between related synapses becomes. There is a basic axiom in neuroscience, called Hebbian Theory that is embodied in the frequent statement, “cells that fire together, wire together.”

To understand this concept, first imagine trying to remember the name of a new friend, a tall, intelligent, stocky, dark-haired, Indian colleague named Uday. To form an association between this complex group of characteristics in your visual image and that name, various parts of your brain with different groups of neurons will be involved together to encode all of that information. Any time you see that same image, and say Uday's name, these same sets of neurons will fire together, and the synaptic network will be strengthened. If you see Uday often, the chemistry at those synapses will actually change to further reinforce the learning and increase the speed and efficiency of the "Uday neural network". Any time your brain recognizes that image coming down the hall, you will quickly recognize Uday.

As you see Uday in the future, and work with him often, amazingly, no matter what you see Uday wearing or what he is doing, one specific neuron is the key central neuronal link to the Uday network. The Uday network will expand and strengthen as more different experiences are had with Uday and different impressions are recorded. Nevertheless the single Uday neuron will be the entry point to this network, sort of a "bar code" for Uday in your brain. Much work has been done of finding the "Uday" neuron (actually the work was done on the Jennifer Aniston neuron, but it's the same idea - Uday's a great guy and Friends is off the air) and verifying this phenomena, which was reported in the excellent peer-reviewed journal, Nature vol. 35, p. 1102. As it turns out, if you spend time socially with Uday, you will also find that his wife, child, relatives, and thesis advisor, will similarly activate the single Uday neuron and its associated network.

In addition to making existing synapses more efficient and faster, learning causes the brain to grow larger. Using optical imaging, it is possible to see this growth occur in animals. Rats learning a physically difficult skill, such as attempting to find and get a treat in a new maze, develop new protrusions, called dendritic spines on the synapses in the part of their brain related to their muscles, the motor cortex, shown in this image.

We are not currently able to see these tiny new dendritic spines form so rapidly in real-time in living human brains. However, with learning of a new motor skill over some significant length of time, brain imaging technology like fMRIs can easily show the increases in brain size for skills ranging from playing the violin to meditating.