n., v. The visual sensation which occurs after playing Guitar Hero; one looks at a still area, ie. a painting or the tv screen after the song is done and the visuals seem to melt together towards one focal point. This is because your eyes still need time to adjust from a constantly moving screen.
Noun: Man, I played 40 minutes of Guitar Hero straight and had an afterglide for about half as long.
Verb: Matt: Dude, what's with Chris?
Shaun: Ah, don't worry about him man. He's just aftergliding.