Listening to music or hearing noises can have an impact on our mood. Now, scientists have found that the genetic variability of the brain's dopamine D2 receptor may be responsible for emotional responses to sound.
Scientists have long wondered about the role that sounds – whether music or noises in our environment – play on our emotional well-being. While there is clearly a link between sound and mood, it varies greatly from one individual to the next. The hypothesis investigated in the new study, published in the journal Neuroscience is that differences in dopamine receptors may drive these differences between individuals.
Dopamine is a major neurotransmitter which helps control the brain's pleasure and reward centres and is involved in mood regulation.
In the brain, dopamine binds to dopamine receptors D1 and D2, which are also the primary targets of anti-psychotic drugs due to the fact that many psychiatric diseases are associated with abnormal levels of dopamine.
The researchers, led by Professor Elvira Brattico from Aarhus University, decided to investigate how variants of the dopamine D2 receptor gene – known as DRD2– modulated people's emotional response to noise and music.
Thirty-eight healthy subjects were recruited, with 26 of them having a specific "GG variant" of DRD2 and 12 a "GT variant". The participants underwent functional magnetic resonance imaging (fMRI) during while performing an implicit emotion-processing task and listening either to music or noise. The scientists questioned them on their mood and assessed their individual mood variation before and after the task.
The scientists observed mood changes depending on the genotype of people and the type of sounds they had been exposed to. In particular, GG subjects saw their mood improve after listening to music, while GT subjects suffered from a mood deterioration after being exposed to noise.
These findings thus suggest that mood changes after music or noise exposure are modulated by DRD2 gene, with genetic variability explaining why responses vary from one individual to the next.