This video shows what happens inside a (straight) man’s brain in the first fraction of a second that he looks at a picture of a sexually desirable woman. There’s a lot going on in there–not just the flare-up of some primordial reptile brain. In my latest column for Discover, I take a look at the history of neuroscience’s exploration of desire, from the earliest studies on tumors that triggered orgasms to the latest in neuroimaging. Check it out.