There's barely more evidence for souls than for god or anything else generally understood as supernatural, which is a set of phenomena that transcend natural laws and probably do not exist in any form. A natural form of soul is
possible - after all we don't fully understand the brain or consciousness, but I wouldn't go beyond speculation without actual evidence. It seems like we die and then we cease to exist, but that would be hard to demonstrate as a certainty.
Colorado ... wouldn't be myself if I didn't play devil's advocate here, however science itself has admitted to having no definitive answer to this. The biochemical properties of the brain include a lot of electrochemical responses as well. Science as determined that energy is never created or destroyed, it merely changes form and moves through physical particles. This being true, when a person dies the energy goes somewhere, and our brains hold a lot of it (not sure what the exact amount is but it's very measurable) and when we die the energy just seems to "vanish". Some have theorized that this is the scientific "spirit" which explains the existence of ghosts and such. There are many metaphysical studies which support this idea (after you filter through all the outrageous ones) and have demonstrated the high possibility that there is life after. So it is valid for even a die hard atheist to agree that there is a soul or spirit, atheists are just against the idea that there is a magical creator, not that life is binary.
I would also like to see a source, preferably from a neurological journal.
Much of energy used in the body is stored in chemical bonds, e.g. in ATP -> ADP + P, so I don't know what "vanishing energy" could be referring to.
What I can say is that the brain is, compared to the rest of our bodies, a rather enigmatic organ. We can readily demonstrate that the heart is a pump and how it can work so well for so long, as opposed to what was formerly thought: that it was a center of heat, or emotion. How a blob of fat with electrical impulses can make consciousness, however, is still out of reach. But lets not stuff gaps in knowledge with what we would like to believe. The fact that we don't know yet is not evidence of the supernatural.