Processing emotions induced by music

Reference
Trainor, L. J., and L. A. Schmidt.
Processing emotions induced by music.
The Cognitive Neuroscience of Music: 310-324, edited by I. Peretz and R. Zatorre, 2003.

Summary
This article compares the neurological and physiological responses to emotional experiences induced by music and other stimuli. The authors' additional area of interest leads them to examine the role music plays in the development of emotional communication between infants and their caretakers.
Instead of inducing emotion directly, music communicates emotion and activates the same brain circuits that function when emotions are induced in other contexts.
Physiological responses to musical emotions include changes in heart rate, respiration rate, blood flow, and skin conductance, which are mostly autonomic and subconscious activities in our body.
As for responses from the central nervous system, listening to music activates both 1) auditory cortex and frontal regions, which are connected with music processing, pitch contour, interval, and pitch memory; and 2) central nervous system including the limbic and sensory areas, as well as those related to cognition and consciousness. There is greater left frontal activation in response to the emotion of joy and happiness. In fear and sadness, greater right frontal region is activated. The result of this study shows that music activates the same emotional circuits as other stimuli.
From the developmental point of view, caretakers use infant-directed playsongs and lullabies to express emotional information to infants and regulate infants' state. Infants respond to these infant-directed songs and learn about social interaction and self-regulation before acquiring language skill.
Interestingly, infants display the same frontal EEG activations as adults (greater right frontal activation in fear and distress), but they do not show the same emotional response to the same orchestral excerpts to which adults listen. Possible explanation includess 1) those orchestral excerpts are too complicated and not enough infant-directed; and 2) sufficient frontal lobe maturation for cognitive appraisal of musical stimuli is yet to be developed after the first 12 months.
Exposure to infant-related musical experience provides infants with tools to express their feelings and communicate with their caretakers. After the development of their language skill and behavioural regulation, music remains a lifelong and powerful channel for communicating emotion without overt action.

Review & Reflection
I had contact with a very cheerful 6-month-old baby for several days during the summer of 2008 and it was most interesting to see how he "learned" different emotions. For example, both happiness and distress were generated by familiarity and repeated activities with caregivers.
After he and I got to know each other and got along reasonably well, I experimented by singing to him. When I first sang to him, he listened with a most concentrated expression ("What is this? Let me find out!"). When I repeated the same song to him in the following days, he started displaying recognition and pleasure.
He had an allergy and took medication for several days. The first time, he tasted and swallowed it. The second time, he took it, but he realized that it didn't taste that good. The third time, he recognized the bottle and flavour and showed resistance to repeating the experience. When he couldn't avoid taking it, he was upset and started crying. It was the first time he displayed signs of distress and cried during the week I spent with him.
Yes, I can see how it's possible for infants to accumulate experiences and develop a repertoire of emotional expressions. It is a combination of instinctive and learned behaviours and music is a very important source of auditory stimulants for infants' interaction with the world.
For adults, listening to music and recognizing emotions communicated by the music is like a recall experience. Most frequently, we recognize a musically induced emotion when we have already experienced that emotion in another context. For that reason, it may be less easy to understand a very sad piece if a person has not experienced much depression nor distress in life. From a performer's point of view, performing music with different emotions can be a way of reaching into our emotion repertoire and expanding it.