“The Man Who Forgot Ray Bradbury” by Neil Gaiman is published in Trigger Warning: Short Fictions and Disturbances.
According to Gaiman in his commentary to the book, this story was written as a ninetieth birthday present for Ray Bradbury. He said it was triggered by being unable to remember the name of an old friend, which is something that happens to all of us now and then.
It is a great example of taking a single occurrence, an idea, and running with it, making it into something amazing. Gaiman manages to evoke the feelings and thoughts that someone who is losing their memory might have, and to make those thoughts and feelings utterly believable and real.
It was difficult to follow in places, but that was by design. The story is written in the first person from the point of view of the person losing their memory, and it is an effective way to get across the confusion caused by the lack of labels off which to hang thoughts and concepts. Loved it.