Wednesday, April 21, 2010

What Is the Memory Capacity of the Brain?



What is the memory capacity of the human brain? Is there a physical limit to the amount of information it can store?

Mr. Osborne, may I be excused? My brain is full,” a student with a particularly tiny head asks his classroom teacher in a classic Far Side comic by Gary Larson. The deadpan answer to this question would be, “No, your brain is almost certainly not full.” Although there must be a physical limit to how many memories we can store, it is extremely large. We don’t have to worry about running out of space in our lifetime.
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 (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 would have to leave the TV running continuously for more than 300 years to use up all that storage.
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.
This is good news because our brain can keep up as we seek new experiences over our lifetime. If the human life span were significantly extended, could we fill our brains? I’m not sure. Ask me again in 100 years.

Paul Reber, professor of psychology Northwestern University

Sunday, April 18, 2010

Cognition Improved by Mindfulness Meditation



Some of us need regular amounts of coffee or other chemical enhancers to make us cognitively sharper. A newly published study suggests perhaps a brief bit of meditation would prepare us just as well.

While past research using neuroimaging technology has shown that meditation techniques can promote significant changes in brain areas associated with concentration, it has always been assumed that extensive training was required to achieve this effect. Though many people would like to boost their cognitive abilities, the monk-like discipline required seems like a daunting time commitment and financial cost for this benefit.

Surprisingly, the benefits may be achievable even without all the work. Though it sounds almost like an advertisement for a "miracle" weight-loss product, new research now suggests that the mind may be easier to cognitively train than we previously believed. Psychologists studying the effects of a meditation technique known as "mindfulness " found that meditation-trained participants showed a significant improvement in their critical cognitive skills (and performed significantly higher in cognitive tests than a control group) after only four days of training for only 20 minutes each day.

"In the behavioral test results, what we are seeing is something that is somewhat comparable to results that have been documented after far more extensive training," said Fadel Zeidan, a post-doctoral researcher at Wake Forest University School of Medicine, and a former doctoral student at the University of North Carolina at Charlotte, where the research was conducted.

"Simply stated, the profound improvements that we found after just 4 days of meditation training are really surprising," Zeidan noted. "It goes to show that the mind is, in fact, easily changeable and highly influenced, especially by meditation."