Q:. Do you think it is possible to dream and tell yourself about a joke in your dream that you don’t think you ever heard before?

A: I have heard of that happening. Studies suggest that the brain absorbs 10,000 a minimum bits of sensory data per second—far more than you can consciously decode and recall. (Estimates are that you can only decode consciously 50-60 bits of data.) You may have heard a similar joke in passing without consciously retaining it in personal memory. The belief is that while you are asleep, your hippocampus, your brain’s search engine, replays for your frontal lobes what has happened during the previous 24 hours or so. Much like a movie editor who reviews the takes and decides what to discard and what to keep, the frontal lobes decide what to discard and what to send to long-term memory. Some of the information it may replay for you in dreams, especially if the brain thinks it is important to you.