Imaging the Unconscious

Functional magnetic resonance imaging could bring psychoanalysis into the 21st century.

More than one hundred years ago, Sigmund Freud proposed his pioneering theory that hidden desires in our subconscious drive much of human behavior. While those theories have fallen out of favor in recent decades, scientists are now revisiting some of them -- with new brain imaging tools. The hope is that having a direct window into the brain's hidden processes will shed new light on anxiety disorders, and perhaps help to assess how well behavioral therapies, such as psychoanalysis, target the intricacies of the unconscious mind.

"One of the reasons people departed from Freudian concepts was because they weren't very testable," says Ronald Cohen, professor of psychiatry at Brown University in Providence, RI. "These types of [imaging] experiments would potentially be a more direct way of testing ideas that rose out of traditional psychoanalytic theory."

One of Freud's theories held that after a traumatic event, people might unconsciously associate a normally benign stimulus, say, a friendly golden retriever, with a previously fearful event, such as getting bitten by a Rottweiler. This theory seems to be true in the case of post-traumatic stress disorder (PTSD). Harmless sights and sounds, for instance, such as a bus traveling on down a street, can trigger a panic attack in someone with PTSD who was once involved in a bus crash. Furthermore, the sufferer may not be immediately able to pinpoint the cause of his or her anxiety attack.

Now scientists are using brain imaging techniques to explore how the unconscious fear signal may be turned up in people with PTSD and other anxiety disorders. To study the brain processes underlying anxiety, researchers use functional magnetic resonance imaging (fMRI) to measure a person's brain activity while he or she looks at threatening signals, such as a picture of a fearful face. These frightening pictures will spark activity in the part of the brain known as the amygdala, which is part of the evolutionarily ancient brain involved in processing emotion and fear. To study the unconscious aspects of fear and anxiety, the researchers flash the ominous picture so quickly that subjects don't consciously notice it -- the brain reacts to the image, even though the person cannot determine whether or not they actually saw it.

Last year, Amit Etkin and collaborators at Columbia University showed that people who score high on anxiety tests have a stronger amygdala response to fearful faces when those images are presented below the level of conscious perception than people who score lower on the tests. Their findings suggest that the way people respond unconsciously to the world around them could also affect their daily anxiety levels.

Now the Columbia researchers want to determine if this lab observation can be used therapeutically. To do so, they plan to study 25 people with generalized anxiety disorder, first to determine whether this exaggerated amygdala response is present in people with the disorder, then to see if cognitive behavioral therapy -- one of the best-established forms of talk therapy -- can reduce the exaggerated unconscious response.

"We can use imaging as a way of evaluating the outcome of therapy," says Eric Kandel, a Nobel-prize winning neuroscientist at Columbia University who's collaborating on the project. "Maybe we can take people who have a large [anxiety] signal and turn it down as the result of a therapeutic experience," he says.