Understanding musical anhedonia and brain connections

Some people simply don’t derive pleasure from listening to music. There is nothing wrong with their hearing, and they enjoy plenty of other experiences, but for some strange reason music does absolutely nothing for them. Researchers say this behavioral trait points to a fascinating disconnect between the brain’s auditory and reward networks.

Most studies on the human reward system have assumed global sensitivity, which means a person’s capacity to experience pleasure is a unified trait that applies generally to all types of rewarding stimuli. But around a decade ago, a team challenged this notion by discovering a condition the called “specific musical anhedonia.” Here, the researchers homed in on individuals that did not find music pleasurable, but still enjoyed other rewarding stimuli. Now, that same team at the University of Barcelona has described the underlying mechanism for these individual differences in music reward sensitivity.

The co-author of the study, Josep Marco-Pallarés, says that musical anhedonia is caused by a poor connection between the brain’s auditory network and its reward circuit, rather than any particular dysfunction. This disconnection impairs music’s ability to trigger the reward systems necessary for one to derive pleasure.

“A similar mechanism could underlie individual differences in responses to other rewarding stimuli,” says Josep Marco-Pallarés. “Investigating these circuits could pave the way for new research on individual differences and reward-related disorders such as anhedonia, addiction, or eating disorders.”

To reveal individuals with specific musical anhedonia, researchers developed a questionnaire called the Barcelona Music Reward Questionnaire (BMRQ). This tool measures five distinct ways people engage with music: evoking emotions, regulating mood, fostering social connections, encouraging dance or movement, and pursuing novelty through seeking, collecting, or experiencing music.

Those with the condition tend to score low in all five dimensions; they don’t pick favorites easily, rarely get chills, and react less intensely to music, yet they respond normally to monetary rewards.

Brain imaging scans support this brain disconnect idea. For a typical listener, neuroimaging showed enhanced activity in regions such as the nucleus accumbens, part of the brain’s reward machinery, on hearing pleasant music. Meanwhile, in people with musical anhedonia, MRI scans showed reduced response to music, but not for other pleasures.

“It’s possible, for instance, that people with specific food anhedonia may have some deficit in the connectivity between brain regions involved in food processing and the reward circuitry,” says Marco-Pallarés.

As for why people develop this condition, it remains up for debate. The study proposes that genetics and the environment play a pivotal role. The study also points to particular brain injuries producing similar conditions of selective loss of pleasure.

The study has been published in Trends in Cognitive Sciences.

Source: Cell Press via EurkAlert

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