Brain zaps can alter responses to music

The enjoyment we get from food and sex is generally considered to be an evolutionary mechanism to encourage us to pursue basic biological needs. But humans also have the “unique capacity” to take pleasure from factors that lack a clear physiological benefit, such as art. Now scientists have pinpointed the parts of the brain that give us joyous sensations when we hear music we love. 

In a study published this week in the journal Nature Human Behaviour, a group of researchers from Canada’s McGill University two sets of experiments on a total of 35 volunteers to establish a direct causal relationship between neural pathways in the brain and feelings of pleasure from music.

Participants listened to songs and then were asked to rate their experiences on a four-point scale, from “neutral” to “chills”, while the researchers applied neuroimaging  scanning to the parts of the brain they suspected were involved in feelings of pleasure derived from music.

The study says that in contrast to primary rewards, the “hedonic impact” of listening to music “is driven by its intrinsic ability to change emotional arousal”. It points out that music can evoke a range of emotions, from happiness to sadness, all of which may be associated with some sort of pleasure.

It’s been suggested by music theorists that the emotions evoked by music may arise from features such as anticipation and expectancy.  

Such expectations rely on higher-order parts of the cerebrum that include the auditory cortex as well as the frontal cortical regions to which it connects. These are critical for working memory and predictive thinking. 

While their subjects were listening to music, simultaneously talking about whether they liked or wanted to hear it, the researchers applied transcranial magnetic stimulation (TMS) above the brain’s left dorsolateral prefrontal cortex. This allowed them to monitor the neural pathways that connect frontal lobe regions with the basal ganglia parts of the brain that mediate motor, cognitive, and behavioural functions.

They found that by varying TMS levels, they could increase or decrease neuronal activity, enhancing or diminishing the emotions derived from the music. 

The study’s lead author, Ernest Mas Herrero, from the Montreal Neurological Institute in Canada, says the researchers first studied changes in perceived pleasure and the monetary value assigned to music following either “excitatory, inhibitory or sham” TMS stimulation. 

In a follow up study, they used functional magnetic resonance imaging (fMRI) within the same model to examine the changes in brain activity.

Mas Herrero says their findings demonstrate “for the first time” that how we feel when listening to music can be enhanced or reduced by stimulating the left dorsolateral prefrontal cortex.

He says these findings may provide new insights in understanding the neural mechanism underlying musical pleasure, and open new avenues for research into how external stimulation of circuits within the brain can be used to achieve specific emotional outcomes.