Personally I love to have my hair brushed. I figure of it feels good to me, probably feels decent to a friendly dogYou may not even need treats, if the brushing just feels good to the dog.
Brushing can feel good to a human head.
Horses seem to enjoy being brushed.
I've got a cat that seems to like it.
So I would assume a dog could also come to like it.
I'm sure that starting from a young age would help. And it's probably best if the first brushing is NOT a long session of de-tangling that pulls their hair!