By Dov Michaeli
By now every fifth grader has heard about the limbic system in the brain. But in case you already forgot, it is a system of highly interconnected brain structures that integrates stimuli of emotional content and coordinates reactions to those stimuli. For instance, the structure called the amygdala (see picture on the right) receives stimuli that have to do with survival, and it engenders reactions to them, such as fear and aggression (the familiar flight or fight response). The limbic system also contains the nucleus accumbens which has to do with reward. If you are an ape and an attractive female telegraphs her receptivity to sexual intercourse, it makes a certain area in your brain secrete copious amounts of dopamine which in turn arouses the nucleus accumbens, and you.
What does it have to do with music?
Brain fMRI studies revealed that many areas of the brain “lit up” when volunteers listened to music. Some of those areas, like the auditory cortex, were expected. But the most rewarding finding was the intense activity of the brain reward system (including the nucleus accumbens), and the emotional integrative center of the amygdala. These are very systems that allow us, or the ape, to sense the environment, react to the approaching tiger, run for our lives and feel great when we are safely ensconced in a well-lit and warm cave. This is the connection.
Let’s pause for a second and marvel at the wonderful world of biology. As we became human, certain traits that have very little to do with survival became part of our emotional make-up. Our ancestors started drawing on cave walls; the oldest such drawings, dated to 30,000 -35,000 years ago, were discovered in southern France in the Chauvet cave. And a musical instrument (a kind of flute) dating to the about the same time has recently been discovered. How did the brain accommodate these new artistic stimuli? By engrafting them onto the existing system of emotions and reward, so indispensible for survival. A beautiful example of the conservative nature of evolution (not the political sort; we are talking conservation of energy here).
Not all music is created equal
You can hear the “moonlight” sonata by Beethoven, and then you can listen to the same sonata. What I am trying to say is that the same music can evoke different reactions in the listener. Accomplished musicians know intuitively how to make the notes come alive and pull on your heartstrings. How do they do it? A German study looked at that.
The investigators had a professor of music play a piano piece “by the book”, playing all the right notes, following the prescribed rhythm and cadence, executing flawlessly the dynamic range as prescribed (piano, moderato, forté). The same professor then played the same piece using his own phrasing, varying the rhythm and dynamic range at will. Brain activity of the listeners was studied by fMRI and showed significantly more intense metabolic activity when the more creative version was played, especially by the amygdala and the reward system, which were markedly less active when the less creative version was played.
Another study, also from Germany, examined our capacity to recognize spontaneity. Not surprisingly, they picked jazz as a form of music most associated with variation and improvisation. The researchers, from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, investigated jazz musicians to discover which brain areas are especially sensitive to features of improvised behavior. Answer: the amygdala again. To understand this finding we have to go back to “original intent” (nothing to do with interpretation of the U.S. constitution). An animal, including the human kind, has to be alert to unexpected situations, judge intent and react quickly to menacing circumstances, or else it will end up on the lunch menu. The amygdala are in charge of judging intent (part of the fight of flight reaction). In music, improvisation and spontaneity are by definition unexpected – hence the involvement of the amygdala.
But that’s not all. Other brain areas lit up when jazz improvisations were played; specifically, a network of areas known to be involved in the mental simulation of behavior. Why should we have such ability in the first place? Again, survival; the best way to anticipate the opponent’s next move is to “get into his head”. Hence the capacity to essentially mirror the neural activity, as judged by body language, facial expression, and other cues. When jazz musicians were asked how they anticipated other players’ improvisations, the most common answer was “get into their heads”.
Interestingly, some of the areas involved in the network of mental simulation belonged to the motor cortex. Understandable, if you consider that anticipating an adversary’s next move is critical. But why should listening to musical improvisation activate motor areas? Because rhythm is part of locomotion, as well as music.
Do you have to be a jazz musician, or any musician for that matter, to recognize spontaneity? The answer is no; both musicians and non-musicians could distinguish between rehearsed and non-rehearsed music.
Coming to think of it, this capacity is not restricted to music alone. Spontaneous and honest speech can be distinguished from well-rehearsed and phony speech by people of diverse cultures and educational levels. Could this, in part explain why politicians are so universally disliked?
Dov Michaeli MD PhD is a basic researcher writing at The Doctor Weighs In.