Monists think the mental and the physical are the same kind of thing. There can be feelings without thoughts. There can be thoughts without feelings. PET scans give more accurate timing than Event-Related Potentials. The subtractive method was developed before brain imaging.
Imagery requires a homunculus.
Mental images are publicly observable. Brain images are publicly observable. The shape of an image is arbitrary. A symbol resembles what it symbolises. The proximal reason we eat food is because it tastes good.