According to research, the part of the brain that regulates behavior and performance goes dormant when a musician "lets go" and improvises. That same part of the brain is highly engaged when a musician is reading music or playing a memorized piece. Makes sense.
What about chess? Some players are highly analytical and deliberate; the playing style of others could reasonably be termed improvisational, no? Would the brain scan of, say, a sedulous postional player such as Botvinnik look different from that of an exciting tactician like Tal?
Hat tip: Britannica Blog