Originally meme was defined as an object that replicates using the human brain as a platform, like ideas that spread through language, cultural forms, fashions etc, like genes are replicating in molecular level. I'd like more to think what happens in brain when a meme replicates.
Brain consists of billions pulsing devices called neurons.
When I tell my friend about this nice analogy between genetics and though system my brain replays the pattern and codes it in language, and distributes it to a communication medium. So, meme is a pulse pattern. When you put on a CD you hear memes. You do not know what your favourite music codes but quite likely the surface forms manifest as thoughs or emotions in certain categories, and in a higher level all similarly incubated people start realizing the patters in cultural movements. In brain a single pattern can represent the movement of a finger, a hand, body movement, a though, emotion, depending what target the pattern controls.