All this happened, more or less.

A fundamental principle governing the brain is that neurons respond to change. Changes in illumination or motion automatically activate circuits and provoke attention to the site of change, for that is where information is likely to reside. A reward, therefore, does not have to be something the animal needs, such as food, water, a mate, or relief from pain. Essintially, many events called "rewards" are punctiation marks that, like a white streak in a blue sky, interrupt the stream of experience and, through activation of many brain structures, facilitate the establishment of assosiations. ibid. 21