From this people.com story:
When Mary Steenburgen woke up from minor arm surgery in 2007, her brain was “only music,” an odd result that lead her to a new songwriting career — and one that may earn her another Oscar.
The actress, 66, said that her brain felt out of control immediately after surgery.
“I felt strange as soon as the anesthesia started to wear off,” she told IndieWire. “The best way I can describe it is that it just felt like my brain was only music, and that everything anybody said to me became musical. All of my thoughts became musical. Every street sign became musical. I couldn’t get my mind into any other mode.”
(In a slightly related story, Scientific American has an article titled, The Hidden Dangers of Going Under.)