The Neurochemistry of Favorite Songs
Music can bring back memories, raise goosebumps, or shift a person’s mood. These responses have prompted scientists to investigate how the brain processes musical pleasure. Music is not necessary for immediate biological survival, but it is a widespread part of human life and can carry strong emotional and social meaning.
A study from the Turku PET Centre in Finland examined whether the brain’s mu-opioid receptor (MOR) system is involved in pleasurable music. This system participates in the hedonic aspects of rewards such as food and sex, and in pain regulation. The researchers combined positron emission tomography (PET) with functional magnetic resonance imaging (fMRI), bringing together a measure related to receptor availability and a measure of changing blood-oxygen-level-dependent brain responses.
The results support a relationship between listening to pleasurable music and MOR-system function. They do not, by themselves, amount to a direct measurement of endogenous opioid molecules being released, nor do they establish a single exact mechanism for musical pleasure.
What the PET Study Measured
During PET scanning, participants listened to pleasurable music and a neutral baseline condition. The team used the MOR-targeting radioligand [11C]carfentanil and measured its binding or availability in the brain. In PET research, radioligand binding is an indirect index: it reflects the tracer’s access to receptors and can be influenced by receptor occupancy and other factors. A difference in binding is therefore not equivalent to chemically identifying and counting a burst of naturally produced opioids.
The study reported increased [11C]carfentanil binding during pleasurable music in several cortical and subcortical areas, including the ventral striatum and orbitofrontal cortex. These areas have been associated with reward and, in prior work, with hedonic processing. The authors interpreted their findings as evidence that pleasurable music modulates MOR-system function. The most careful description is that the PET signal changed in a pattern the researchers relate to opioid-system engagement; the imaging result alone should not be paraphrased as unambiguous direct proof of opioid release.
This distinction matters because simplified accounts can make a sophisticated imaging measure sound like a direct chemical assay. The experiment did not inject an opioid or measure a participant’s subjective pleasure as a chemical concentration. It compared tracer binding across listening and baseline conditions, then interpreted that evidence in the context of receptor pharmacology and the wider research literature.
Chills and Individual Differences
Some listeners experience pleasurable chills—sometimes described as shivers or goosebumps—during especially moving passages. The PET study found that [11C]carfentanil binding in the nucleus accumbens during the music condition was associated with the number of pleasurable chills participants experienced. The nucleus accumbens is part of the ventral striatum and is involved in reward-related processing. This association connects a subjective feature of musical enjoyment with a PET measure in a reward-related region; it does not show that every pleasurable response requires chills.
The study also combined PET-derived information about baseline MOR tone with fMRI responses during music and control stimuli. Individual variation in baseline receptor-related measures was associated with differences in pleasure-dependent haemodynamic responses in regions implicated in interoceptive, sensorimotor, and reward processing. Put more simply, people did not all show identical brain-response patterns, and variation in the opioid-receptor measure tracked some of that variation.
These are group-level associations, not a diagnostic test for how much an individual enjoys music. They also do not mean that having more receptors necessarily makes a person more musical or guarantees stronger pleasure. The findings point to one possible contributor among many, including musical familiarity, memory, expectation, attention, culture, and personal preference.
Why the Opioid System Is Relevant
The brain’s opioid system is involved in the pleasurable, or hedonic, component of rewards and also participates in pain modulation. That makes it a plausible system to investigate when studying music, which can be deeply rewarding and has been associated in other contexts with changes in pain experience. The Turku work extends investigation of MOR function beyond primary rewards to an aesthetic reward: listening to music people find pleasurable.
The study’s findings are consistent with the possibility that opioid-system function contributes to the intensity of musical enjoyment. But the PET-fMRI design does not settle every step in the chain from sound to emotion. Music is processed through interacting auditory, memory, prediction, autonomic, motor, and reward systems. The study provides evidence about MOR-related measures and associated brain responses, rather than a complete account of how a song produces a particular feeling.
What the Findings May—and May Not—Mean for Pain
Because opioid systems are also involved in pain relief, the researchers suggest that their findings may help explain previously observed pain-relieving effects of music. That is a reasonable research hypothesis, not proof that this experiment demonstrated clinical analgesia. The study focused on pleasurable music and brain imaging; it was not a treatment trial measuring whether music reduced pain in patients, how large any reduction was, or how long it lasted.
Music-based approaches may be worth studying as supportive tools in pain management and mental-health care. The present results do not show that music can replace established treatment, that all music works equally well, or that the opioid pathway is the only reason music might influence pain or mood. Future clinical work would need to test practical outcomes directly and identify which listeners and settings benefit.
A Careful Reading of the Evidence
The report describes the study as the first neuroimaging evidence that pleasurable music modulates the cerebral MOR system. Its significance lies in joining PET measures of receptor availability with fMRI measurements related to dynamic pleasure ratings, and in finding relationships with chills and individual differences. The result is informative without requiring the stronger claim that researchers directly witnessed a specific quantity of opioid release or pinned down the exact biological mechanism.
PET and fMRI answer different questions. PET with [11C]carfentanil provides information about radioligand binding at MORs under the conditions studied. fMRI tracks haemodynamic responses, which are indirect correlates of neural activity. Their combination can relate receptor-system measures to brain-response patterns, but neither modality directly reads a person’s feelings or provides a complete molecular narrative. The researchers’ interpretation should be presented as evidence that the MOR system is involved, with the measurement limitations kept visible.
The study is also a starting point rather than a final account of musical pleasure. Follow-up studies could investigate how familiarity, musical structure, expectation, and emotional context affect receptor-related measures; whether similar patterns appear across different kinds of music; and how these findings relate to pain outcomes in controlled clinical settings. Replication and carefully designed intervention trials would be needed before drawing practical treatment conclusions.
For now, the central finding is that pleasurable music was associated with changes in a PET measure of MOR availability in reward-related regions, and those measures related to chills and to differences in fMRI responses. This adds evidence that the opioid system participates in aesthetic reward. It offers a plausible route for studying music’s emotional and potentially pain-related effects, while leaving the precise mechanism and therapeutic implications for future research.
Source
Neuroscience News, “Music-Induced ‘Chills’ Trigger Natural Opioids in the Brain,” April 16, 2025. The report summarizes the open-access study “Pleasurable music activates cerebral μ-opioid receptors: a combined PET-fMRI study,” by Vesa Putkinen and colleagues, published in the European Journal of Nuclear Medicine. https://neurosciencenews.com/music-chills-opioids-neuroscience-28657/
