Hallucinatory illnesses come in many forms. Some hear voices in their heads, others see small people, threatening insects or bold colors that don’t exist. Still others, it turns out, hallucinate in musical notes. Neurologist and best-selling author Oliver Sacks describes the phenomenon in a new paper published in the journal Brain.

More than a quarter of patients who suffer from hallucinations manifest those visions as “text hallucinations,” Sacks writes. This could include seeing lines of print, letters, numbers, musical notes or other notations. Musical notes seems to be the rarest form of this type of hallucination.

Sacks, however, specializes somewhat in musical hallucinations. Oftentimes, Sacks writes, patients do not volunteer the fact that they see musical notes unless specifically asked about it. He’s encountered twelve cases of people who see visions of musical notation, many of whom also suffer from Parkinson’s, epilepsy or other conditions. In 1995, for example, Sacks received this letter from “Marjorie J.”:

‘I am a 77-year-old woman with glaucoma damage to mostly the lower half of my vision. About two months ago, I started to see music, lines, spaces, notes, clefs—in fact written music on everything I looked at, but only where the blindness exists. I ignored it for a while, but when I was visiting the Seattle Art Museum one day and I saw the lines of the explanatory notes as music, I knew I was really having some kind of hallucination…. I had been playing the piano and really concentrating on music prior to the musical hallucinations…. It was right before my cataract was removed, and I had to concentrate hard to see the notes. Occasionally I’ll see crossword puzzle squares…but the music does not go away. I’ve been told the brain refuses to accept the fact that there is visual loss and ﬁlls in—with music in my case.’

Eventually, Marjorie J.’s hallucinations began to fade, and when Sacks followed up with her fifteen years later she no longer suffered from musical hallucinations at all. Others, like Christy C., see music only when they fall ill:

‘As a child, I ran high fevers when sick. With each spell, I would hallucinate. This was an optical hallucination involving musical notes and stanzas. I did not hear music. When the fever was high, I would see notes and clef lines, scrambled and out of order. The notes were angry and I felt unease. The lines and notes were out of control and at times in a ball. For hours, I would try to mentally smooth them out and put them in harmony or order. This same hallucination has plagued me as an adult when feverish.’

Seven of Sacks’ eight case studies examined in the paper belong to people who frequently play the piano or read music, though the ability to read music is not a prerequisite for hallucinating musical scores. Indeed, while the musical notes looked legitimate on first glance, when the hallucinating patients took a closer look, the scores turned out to be mostly musical gibberish. Sacks takes a stab at explaining the phenomenon, though adds that much understanding is still lacking when it comes to musical hallucinations:

Normally the early visual system analyses forms and then sends the information it has extracted to higher areas, where it gains coherence and meaning. Damage at different levels can break this ﬂow of information. In this case, a focal stimulation or spontaneous activation of the visual word form area (or analogous areas involved in musical perception), unguided from above by higher-order mechanisms or from below by actual perception, provides only a crude simulacrum of real text or score—pseudo-texts, pseudo-scores, which lack some features of reality while exaggerating others.

In other words, people who suffer from musical hallucinations won’t be able to harness those scores to become the next Beethoven or Mozart, just as most people cannot turn their dreams into best-selling novels.

More from Smithsonian.com:

Why Oliver Sacks Is One of the Great Modern Adventurers

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