music and the brain -- 2/21/18

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Today's selection -- from The Brain's Way of Healing by Norman Doidge, M.D. There is a special connection between music and the brain, one that bypasses the neocortex and impacts the brain in fundamental and potentially therapeutic ways:

"Brain scan studies show that when the brain is stimulated by music, its neurons begin to fire in perfect synchrony with it, 'entraining' (the practice of modifying one's brainwaves to a desired frequency) with the music it hears. This happens because the brain evolved to reach out into the world, and the ear works as a transducer. Transducers trans­form energy from one form into another. For instance, a loudspeaker transforms electrical energy into sound. The cochlea inside our ear transforms patterns of sound energy from the external world into patterns of electrical energy that the brain can use internally. Even though the form of the energy changes, the information carried by the wave pat­terns is often preserved.

Cross section of the cochlea

"Since neurons fire in unison to music, music is a way to change the rhythms of the brain. An expert in the neuroplasticity of sound, Dr. Nina Kraus of Northwestern University, and her lab colleagues recorded the sound waves given off by a Mozart serenade. They also placed an electrical sensor on a person's scalp to record his brain's waves as he lis­tened to the Mozart. (Brain waves are the electrical waves produced by millions of neurons working together in time.) Then they played back the patterns of the brain waves firing. Amazingly, they found that the sound waves from the Mozart piece and the brain waves that they trig­gered looked the same. They even found that the brain waves in the brain stem sounded the same as the music that triggered them!

"Neurons can be entrained by a variety of nonelectrical stimuli, in­cluding light and sound; these effects can be demonstrated using an EEG. Many kinds of sensory stimulation can radically alter the fre­quency of brain waves. For example, in a hyperexcitable brain, as in some cases of photosensitive epilepsy, strobe lights (flashing at about ten times a second) can cause large numbers of neurons to fire synchro­nously; a victim may have a seizure, lose consciousness, and start writh­ing out of control. Music can cause seizures as well.

On the left, the brain at rest. On the right, the brain while listening to music.

"Entrainment is so graphic that when people are hooked up to EEGs and asked to listen to a waltz rhythm of 2.4 beats a second, their brain waves' dominant frequency spikes at 2.4 beats per second. No wonder people move to the beat of a song -- much of the brain, including the motor cortex, is entrained to that beat. But entrainment also happens between people. When musicians jam, their dominant brain waves be­gin to entrain with one another. In 2009 the psychologist Ulman Lin­denberger and his colleagues hooked nine pairs of guitarists up to EEGs, while they played jazz together. The brain waves of each pair began to entrain together, to synchronize their dominant neuronal firing rates. No doubt this is part of what musicians' 'getting into a groove' is all about. But the study also showed that entrainment didn't occur only be­tween the musicians.

"Different regions of individual musicians' brains synchronized as well, so that overall, many more areas of the brain showed the dominant frequency. Not only were the musicians playing together in an ensemble; the coordinated ensembles of the neurons within each player's brain were playing together with the ensembles of neurons in their fellow musicians' brains.

"Because so many brain disorders are caused when the brain loses its rhythm and fires in an offbeat or 'dysrhythmic' way, music therapy is especially promising for these conditions. The rhythms of music medi­cine can provide a noninvasive way to get the brain back 'on beat.' Kraus and others have shown that the subcortical brain areas, which were once thought to lack plasticity, are in fact quite neuroplastic.

"Different rhythms of neuronal activity correspond to different mental states. When a person is sleeping, for instance, the dominant rhythm­ that is, the brain waves with the highest amplitude -- on an EEG are those that are firing 1 to 3 brain waves per second (or 1 to 3 Hz). When a person is awake and in a calm, focused state, the brain wave frequency is faster, about 12 to 15 Hz; as she concentrates on a problem, the 15 to 18 Hz waves are dominant; and when she is worrying about a problem and anxious, the waves increase to 20 Hz. Normally our brain rhythms are set by a combi­nation of factors: external stimulation, our level of arousal, and our con­scious intentions (say, to focus on a problem, or to go to sleep). Within the brain are multiple 'pacemakers' that, like a conductor, generate the timing of these rhythms. But with neuroplastic training, we can develop some control over our brain rhythms. Neurofeedback ... trains a person whose brain rhythms are off to control them. So it is excellent for people with attention or sleep problems, or a noisy brain in general."

author:	Norman Doidge
title:	The Brain's Way of Healing: Remarkable Discoveries and Recoveries from the Frontiers of Neuroplasticity
publisher:	Penguin Random House LLC
date:	Copyright 2015, 2016 Norman Doidge
pages:	344-347, 350