Probiotics are microscopic living things inside your body that are thought to be beneficial. They are sometimes referred to as "good bacteria," and are key to a "healthy gut." Well, Mark Lyte from Texas Tech University Health Sciences Center, writing in Bioessays, says that these intestinal microbes could be used as devices to deliver neurochemicals directly into the gut. It's "microbiology meets neuroscience," he says, citing evidence that intestines are a viable route for influencing neurological function. In other words, a happy digestive system means a happy mind. More here