If you've ver gotten the strange feeling that you’re repeating an experience, researchers have about 40 theories for what was going on in your brain. Learn how déjà vu might work in this episode of BrainStuff.Learn more about advertising on the HowStuffWorks podcasts at www.howstuffworks.com/advertisers.htmAnd to learn about your ad choices when listening to podcasts, visit https://www.howstuffworks.com/privacy.htm#ad-choices