Columbia University Medical Center researchers have identified the neurocircuit that controls the brain's response to fear. Results suggest that it may be possible to understand psychiatric disorders, such as anxiety or depression, from the underlying neurophysiology - workings of the brain.
They accomplished this using an adapted version of an attention control test, and a neuroimaging machine that enables analysis of function in the brain.
Published in the Sept. 21, 2006 issue of Neuron, the research is a continuation of work led by senior author Joy Hirsch, Ph.D., professor of neuroradiology and psychology, and director of the fMRI Research Center at Columbia University Medical Center. In a previous Neuron paper (Dec. 16, 2004), Dr. Hirsch and team identified a structure in the brain important for emotional processing - the amygdala - that was shown to light up with activity when people unconsciously detect fearful faces.
"People are exposed to an ever increasing amount of stimuli in our everyday lives, and so we realized that the brain must employ a processing mechanism to prioritize and refine responses -we don't run away from every loud sound or unexpected sight," said Dr. Hirsch. "Following the discovery of the amygdala's role in fear response, we decided to explore the finer points of the neurocircuitry of fear - how it is regulated/controlled in the brain."
To accomplish the tricky task of studying fear in the brain, she turned to a method described in the Dec. 2005 Nature Neuroscience. In a paper featured on the cover of this journal, Dr. Hirsch and Tobias Egner, a post-doctoral researcher in her lab, described how the Stroop test, a psychological test of mental vitality and flexibility, can be adapted to enable the observation of control mechanisms in the brain, using a high-resolution version of functional magnetic resonance imaging (fMRI).
The standard Stroop test asks participants to name the ink color of a printed color word. Performance is typically worse if word and color are incongruent (e.g., YELLOW printed in red ink) than when the two attributes are congruent (RED printed in red ink).
For the 2006 Neuron paper, Dr. Hirsch and her team developed an emotional Stroop test with fearful and happy faces, with FEAR or HAPPY written across the images. Working with 19 healthy volunteers, the test was administered while participants underwent an fMRI scan.