Tone-deaf people–those who can’t hold a tune–appear to be missing a specific neural circuit, according to research published today in the Journal of Neuroscience.

Researchers used a variation of MRI called diffusion tensor imaging to compare neural circuits–specifically those between the right temporal and frontal lobes–in the brains of people who are tone-deaf and those who are not.

According to a press release from the Society for Neuroscience, which published the research,

This region, a neural “highway” called the arcuate fasciculus, is known to be involved in linking music and language perception with vocal production.The arcuate fasciculus was smaller in volume and had a lower fiber count in the tone-deaf individuals. More notably, the superior branch of the arcuate fasciculus in the right hemisphere could not be detected in the tone-deaf individuals. The researchers speculated that this could mean the branch is missing entirely, or is so abnormally deformed that it appears invisible to even the most advanced neuroimaging methods.