Your brain is a three-pound miracle. It is the most complex thing in the known universe. It is a powerhouse; despite being only three pounds, it utilizes 25 percent of your body's energy. It contains 100 billion nerve cells known as neurons. Each of these cells can make connections to other neurons, forming a vast array of interconnections. These connections can range from 100 to 100,000, averaging at about 10,000. And in any given moment, each of these connections can be in any one of ten electrical states. If you do the math, the numbers are staggering. At 100 billion neurons, there is one neuron for each star in the Milky Way galaxy. The brain is also closely wired to the body, with 3 million nerve connections going from the body to the brain and one million going from the brain to the body. These connections will turn out to be very useful when you are doing body-based vipassana (mindfulness) meditation.

Plastic Fantastic

Not that long ago, say twenty years ago, neuroscientists believed that neurons did not regenerate. If you lost a neuron, whether due to a brain trauma or a night of heavy drinking, these neurons were lost forever. Now, with advances in brain imaging technology, scientists have realized that the brain is much more plastic (that is, its capacity to change in response to experience) than they thought. In fact, not only do neurons form new connections with each other promiscuously, after loss there can be neurogenesis.

This discovery of what is called “neuroplasticity” has invigorated the field of meditation research and provides a neurophysiological explanation for the benefits seen from meditation practice. The discovery of neuroplasticity highlights the amazing fact that experience changes the brain. It's not just Prozac in your brain that can make changes. Like all experiences, meditation can change the physical structure of your brain, and each time you sit down to meditate you are forming new neural connections and perhaps even developing new neurons. Of course, the Buddha didn't have this scientific knowledge, but his insights are now being confirmed by science. How cool is that?

A Million to One

Despite the brain being the most complex thing in the known universe with a prodigious processing capacity, consciousness is not what you think. Most of what the brain does is unconscious. Of all the information coming into your brain, only one millionth of that information gets to consciousness. Consciousness seems vast and everywhere, but this is an illusion.

The late psychologist Julian Jaynes likened consciousness to “asking a flashlight in a dark room to look around for something that does not have any light shining upon it.” As far as the flashlight is concerned the room is completely bright.

At any given moment your brain is processing approximately 11 million bits of information per second from your sensory organs. By way of comparison, your television processes 4 million bits per second and your telephone about 4,000.

Of these 11 million, you can only be consciously aware of fifty at the maximum. Tor Norretranders estimates that the average is closer to sixteen bits. It makes you think of those t-shirts bemoaning the fact that all you got was a lousy t-shirt: “You mean my brain is the most complex entity in the known universe and all I got was a lousy sixteen bits of information?!”

This bottleneck is where meditation is aimed. You would not want to be conscious of everything that came your way; that would be overwhelming. However, you do want to have more choice in how the precious resource of your present moment attention is directed and this is what mindfulness meditation will give you — choice.

Selective Inattention

Why is this important? Attention is one of humanity's most precious commodities. Being in the present is the currency of living. You either spend this currency living in the present moment or by squandering it, worrying about the future, or regretting the past.

If consciousness is a precious and fragile resource, it behooves you to be as attentive as possible to make the most of those sixteen bits of information. Who knows, with practice you can even expand that bandwidth to the maximum of fifty!

One of the consequences of this bandwidth problem is called selective inattention. Selective inattention is a fascinating phenomenon. Imagine that you are watching a video of six people, three in black shirts and three in white shirts, with each team passing a basketball back and forth to each other. Your job is to count how many times the basketball is passed between the players on the team. Meanwhile, a guy in a gorilla suit walks into the middle of the scene, beats his chest, and exits stage left. Of course you would notice the gorilla, right? Maybe. About half the people watching the video did not see the gorilla! If you are not seeing the “gorillas” in the course of your day, what else are you missing?

Chocolate Cake or Fruit Salad

An intriguing study shows just how fragile attention can be; how easily overwhelmed it can become. In this study, research subjects were given digits to remember. One group had to memorize a two-digit number and the other group a seven-digit number. After memorizing the number the subjects walked down the hall where they were presented with a snack choice: “decadent” chocolate cake or “healthy” fruit salad. Will power is a function of the prefrontal cortex (this part of the brain is examined in more detail below). What would you predict? The subjects who had to memorize the longer number chose the chocolate cake twice as much as the subjects memorizing the shorter number. Your poor consciousness gets so easily overwhelmed. Better beef it up with some meditation!