Music has the capacity to make us well up or to pump us up, but for some people it has no effect whatsoever. No, these melodically immune individuals do not lack a soul, but instead experience what the authors of a new study call “specific musical anhedonia”, meaning their brains simply don’t respond to music.
By scanning the brains of 15 people with musical anhedonia and comparing them to those who don’t experience this strange phenomenon, the researchers were able to figure out how neural activity differs between the two groups, thus explaining why some people are unmoved by music.
Using functional magnetic resonance imagery (fMRI), the team found that when those with musical anhedonia listen to music, they experience much lower levels of activity in a brain region called the nucleus accumbens (NAcc) than people without the condition.
Given that the NAcc is part of the brain’s reward circuit, this would seem to explain why these people are rarely elated by the sound of music. However, when taking part in a gambling task, NAcc responses were as strong in those with musical anhedonia as those without it, suggesting that their reward circuit works fine and that the issue is specifically related to music.
The researchers then turned their attention to the level of connectivity between a reward structure called the ventral striatum – which includes the NAcc – and the auditory cortex of the brain, where sounds are processed.
Subjects with musical anhedonia showed much lower connectivity along this pathway than subjects with normal reactions to music. A further group of 15 people with extremely acute sensitivity to music then showed particularly high connectivity between the ventral striatum and the auditory cortex.
Publishing their findings in the Proceedings of the National Academy of Sciences, the researchers write that “musical anhedonia may be associated with a reduction in the interplay between the auditory cortex and the subcortical reward network, indicating a pivotal role of this interaction for the enjoyment of music.”
What causes these differences in connectivity along this key musical pathway, however, remains unclear.