Today, I came across the case study of a man who, due to a brain lesion, no longer feels emotion from listening to music. The authors term this phenomenon, “musical anhedonia”, although, technically, anhedonia refers to a lack of pleasurable emotion in response to a stimulus. But no matter. I was intrigued, because of the specificity of this condition. The man can feel pleasure in general, and he perceives the music just as well as he ever did, but he just doesn’t respond emotionally to music.
The lesion that the patient had was in the right inferior parietal lobule, a small region within the parietal lobe of the brain. This is interesting, because the parietal lobe is not often associated with emotional experience. In fact, the limbic system of the brain (medial prefrontal cortex, ventral striatum, etc.) is usually activated in response to pleasurable music, just as it is activated in response to other rewards in life (check out this review to read more about music, the brain and musical listening disorders). The parietal lobe, rather, is responsible for integrating sensory information (such as sounds) and mapping and manipulating objects. And the inferior parietal lobule – the particular region that was damaged in the musically anhedonic man’s brain – is involved in perception of time and speed, mental math, and perception of feelings. One other music study did find that this region responded to consonant (pleasant-sounding) chords and not to dissonant chords.
So what can this mean? Perhaps this small part of the brain (which is actually larger in women than in men) is responsible for mapping emotion onto sensory stimuli, in an almost abstract way. The brain might use this area to learn to associate certain chords with certain feelings. The reason I say that this process is “abstract” is because we have a lower-level emotional consolidation system for learning about stimuli that produce more intense emotion, such as fear. The right inferior parietal lobule might be reserved for more complicated associations that are learned over time.
Of course, this is just speculation. It would help to know if the man in the case study is experiencing any other emotional abnormalities. For example, is he also having trouble associating paintings or other visual art with emotion?
There is something about music and its processing that is distinctive, definitely. But I still cling to the idea that our brains were not adapted especially for music. Case studies and experiments such as the ones I mentioned above help to elucidate that hazy link between basic brain function and high-level musical listening experience.