← Buddha’s Brain The Practical Neuroscience of Happiness, Love, and Wisdom
Buddha’s Brain The Practical Neuroscience of Happiness, Love, and Wisdom Chapter 1. The Self-Transforming Brain
Author: Rick Hanson Publisher: New Harbinger Publications: Oakland, CA Publish Date: 2009 Review Date: Status:📚
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When your mind changes, your brain changes, too. In the saying from the work of the psychologist Donald Hebb: when neurons fire together, they wire together—mental activity actually creates new neural structures (Hebb 1949; LeDoux 2003). As a result, even fleeting thoughts and feelings can leave lasting marks on your brain, much like a spring shower can leave little trails on a hillside. For example, taxi drivers in London—whose job requires remembering lots of twisty streets—develop a larger hippocampus (a key brain region for making visual-spatial memories), since that part of the brain gets an extra workout (Maguire et al. 2000). As you become a happier person, the left frontal region of your brain becomes more active (Davidson 2004). What flows through your mind sculpts your brain. Thus, you can use your mind to change your brain for the better—which will benefit your whole being, and every other person whose life you touch.
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Your brain is three pounds of tofu-like tissue containing 1.1 trillion cells, including 100 billion neurons. On average, each neuron receives about five thousand connections, called synapses, from other neurons (Linden 2007). At its receiving synapses, a neuron gets signals—usually as a burst of chemicals called neurotransmitters—from other neurons. Signals tell a neuron either to fire or not; whether it fires depends mainly on the combination of signals it receives each moment. In turn, when a neuron fires, it sends signals to other neurons through its transmitting synapses, telling them to fire or not. A typical neuron fires 5– 50 times a second. In the time it takes you to read the bullet points in this box, literally quadrillions of signals will travel inside your head.
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Each neural signal is a bit of information; your nervous system moves information around like your heart moves blood around. All that information is what we define broadly as the mind, most of which is forever outside your awareness. In our use of the term, the “mind” includes the signals that regulate the stress response, the knowledge of how to ride a bike, personality tendencies, hopes and dreams, and the meaning of the words you’re reading here.
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The brain is the primary mover and shaper of the mind. It’s so busy that, even though it’s only 2 percent of the body’s weight, it uses 20– 25 percent of its oxygen and glucose (Lammert 2008). Like a refrigerator, it’s always humming away, performing its functions; consequently, it uses about the same amount of energy whether you’re deep asleep or thinking hard (Raichle and Gusnard 2002).
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The number of possible combinations of 100 billion neurons firing or not is approximately 10 to the millionth power, or 1 followed by a million zeros, in principle; this is the number of possible states of your brain. To put this quantity in perspective, the number of atoms in the universe is estimated to be “only” about 10 to the eightieth power.
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Conscious mental events are based on temporary coalitions of synapses that form and disperse—usually within seconds—like eddies in a stream (Rabinovich, Huerta, and Laurent 2008). Neurons can also make lasting circuits, strengthening their connections to each other as a result of mental activity.
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The brain works as a whole system; thus, attributing some function—such as attention or emotion—to just one part of it is usually a simplification. Your brain interacts with other systems in your body—which in turn interact with the world—plus it’s shaped by the mind as well. In the largest sense, your mind is made by your brain, body, natural world, and human culture—as well as by the mind itself (Thompson and Varela 2001). We’re simplifying things when we refer to the brain as the basis of the mind. The mind and brain interact with each other so profoundly that they’re best understood as a single, co-dependent, mind/brain system.
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Throughout history, unsung men and women and great teachers alike have cultivated remarkable mental states by generating remarkable brain states. For instance, when experienced Tibetan practitioners go deep into meditation, they produce uncommonly powerful and pervasive gamma brainwaves of electrical activity, in which unusually large regions of neural real estate pulse in synchrony 30– 80 times a second (Lutz et al. 2004), integrating and unifying large territories of the mind.
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Although life has many pleasures and joys, it also contains considerable discomfort and sorrow—the unfortunate side effect of three strategies that evolved to help animals, including us, pass on their genes. For sheer survival, these strategies work great, but they also lead to suffering (as we’ll explore in depth in the two next chapters). To summarize, whenever a strategy runs into trouble, uncomfortable—sometimes even agonizing—alarm signals pulse through the nervous system to set the animal back on track. But trouble comes all the time, since each strategy contains inherent contradictions, as the animal tries to: Separate what is actually connected, in order to create a boundary between itself and the world, Stabilize what keeps changing, in order to maintain its internal systems within tight ranges, Hold onto fleeting pleasures and escape inevitable pains, in order to approach opportunities and avoid threats
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Virtue simply involves regulating your actions, words, and thoughts to create benefits rather than harms for yourself and others. In your brain, virtue draws on top-down direction from the prefrontal cortex (PFC);“prefrontal” means the most forward parts of the brain, just behind and above the forehead, and your “cortex” is the outer layer of the brain (its Latin root means “bark”). Virtue also relies on bottom-up calming from the parasympathetic nervous system and positive emotions from the limbic system. You’ll learn how to work with the circuitry of these systems in chapter 5.
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Since your brain learns mainly from what you attend to, mindfulness is the doorway to taking in good experiences and making them a part of yourself (we’ll discuss how to do this in chapter 4). Virtue, mindfulness, and wisdom are supported by the three fundamental functions of the brain: regulation, learning, and selection. Your brain regulates itself—and other bodily systems—through a combination of excitatory and inhibitory activity: green lights and red lights. It learns through forming new circuits and strengthening or weakening existing ones. And it selects whatever experience has taught it to value; for example, even an earthworm can be trained to pick a particular path to avoid an electric shock. These three functions—regulation, learning, and selection—operate at all levels of the nervous system, from the intricate molecular dance at the tip of a synapse to the whole-brain integration of control, competence, and discernment. All three functions are involved in any important mental activity. Nonetheless, each pillar of practice corresponds quite closely to one of the three fundamental neural functions. Virtue relies heavily on regulation, both to excite positive inclinations and to inhibit negative ones. Mindfulness leads to new learning—since attention shapes neural circuits—and draws upon past learning to develop a steadier and more concentrated awareness. Wisdom is a matter of making choices, such as letting go of lesser pleasures for the sake of greater ones.