…was, apparently, frontotemporal dementia:
Ravel and Dr. Adams were in the early stages of a rare disease called FTD, or frontotemporal dementia, when they were working, Ravel on “Bolero” and Dr. Adams on her painting of “Bolero,” Dr. Miller said. The disease apparently altered circuits in their brains, changing the connections between the front and back parts and resulting in a torrent of creativity.
“We used to think dementias hit the brain diffusely,” Dr. Miller said. “Nothing was anatomically specific. That is wrong. We now realize that when specific, dominant circuits are injured or disintegrate, they may release or disinhibit activity in other areas. In other words, if one part of the brain is compromised, another part can remodel and become stronger.”
Thus some patients with FTD develop artistic abilities when frontal brain areas decline and posterior regions take over, Dr. Miller said.