LYING FOR LOVE is becoming as commonplace as lying for a business or political advantage. From candidates to couch potatoes, everyone hiding a love secret squirms when allegations of infidelity surface. But what happens if you are accused of cheating, the stakes are high, and you need to prove your innocence? For about $10,000 there is functional magnetic resonance imaging (fMRI) that can trace a lie by pinpointing an area of the brain where lies originate and truth prevails.

Findings from the Brain Mapping Center at UCLA, published in the Annals of Neurology this year, show how neuroimaging can help distinguish belief, disbelief and uncertainty in real time. David Langleben, M.D., a University of Pennsylvania neurologist and psychiatrist, said on National Public Radio: “Three areas of the brain generally become more active during deception.” Essentially, he said, it takes more brain activity to tell a lie “than when you just say the truth.” In other words truth comes more naturally than a lie, which on a brain scan can be tracked as it forms and is depicted as increased blood-flow activity to specific areas. While there is a perceived notion that it is easy to tell a lie, it appears to be quite the contrary. To lie, one must first know the truth. The surprise finding can be disconcerting to those who talk in shades of gray to try to veil the truth.

Sean A. Spence, M.D., in writing about “The Deceptive Brain” for the Journal of the Royal Society of Medicine, five years ago reported that “responding with a lie demands something ‘extra’ . . . a hypothesis that we can test by means of functional neuroimaging.”

Today deception-analysis software and MRI are being used by the California-based No Lie MRI. Requests for brain scans are coming from businesses as well as those in relationships who have been accused of infidelity and wish to prove their innocence.

While we often associate love lies with infidelity, an American in Paris tells us that love and lying may be inexplicably entwined. Twenty-something freelance translator Aimee Charest said, “A resounding oui for ladies who lie for relationships — guilty as charged. Everyone is afraid of being alone or being rejected. I think the real problem is that we lie to ourselves too much.”

Lying to oneself can create both illusions and delusions. Bloggers are often asked, “Is it cheating if you are married and having a secret on-line relationship?” (Such questions are often prefaced with the words “But I really love my spouse.”) The answer is always, “Yes, if it’s a secret, it’s emotional infidelity.”

If we follow the logic that it is easier to tell the truth than to tell a love lie, “what is love?” I asked a group of people at an upscale café in midtown Providence. Answers from patrons and staff fell into two categories: romantic and biological. Sean Scannell, maitre d’, said, “Love is when the faults of your other are no longer recognizable.” From behind the bar, Christopher Perrino quickly responded: “Love is chemistry.”

And chemistry may be why co-habitation is up in 14 countries even though marriage is down.

In Dubai, those who are unmarried but living together in committed relationships are breaking the law. Roger Manny, a U.S. architect managing a project in Dubai, says, “It is whispered that love lies and cheating do go on here except in marriages among the more fundamentalist couples. Out of respect for the sanctity of family, they are expected to live by higher standards.”

Yet, he pointed out, “In my travels around the world, the bigger issue is not lying for love, but looking for love. Everywhere people are trying to find someone to love, romance, marry and maintain the intimacy of their initial passion.”

In the search for lifelong love, some wonder if they should take brain scans before marriage to track the blood-activity pattern of truth or lies to interpret each other’s intentions. Steven C. Schachter, M.D., a professor of neurology at the Harvard Medical School, said: “This form of high-tech mind reading gives new meaning to the phrase ‘Go with the flow.’ But what ever happened to looking into someone’s eyes?”

Rita Watson ( www.ritawatson.com ) is a daily blogger and a monthly contributor.