Emotional Control Circuit of Brain's Fear Response Discovered
Columbia University Medical Center researchers have identified an emotional control circuit in the human brain which keeps emotionally intense stimuli from interfering with mental functioning. These results significantly enhance our understanding of the neurobiology underlying psychiatric disorders involving emotional control, such as post traumatic stress disorder (PTSD) or depression.
The research employed a novel test in which subjects were forced to detect and resolve attentional conflict created by emotionally powerful stimuli. Brain activity was monitored using functional magnetic resonance imaging (fMRI) that can detect moment-to-moment changes in neural activity. fMRI is a version of the widely-used clinical MRI scanning technique.
The study, which is published in the Sept 21, 2006 issue of Neuron, was led by a Columbia University Medical Center M.D./Ph.D. student, Amit Etkin, who explained that, "Tremendous knowledge exists about how our brains deal with cognitive distractions, but we know very little about how we deal with emotional distractions. This is something we constantly do in our everyday lives, otherwise we would be overwhelmed by every emotional trigger we encounter."
Dr. Etkin worked in the Columbia University Medical Center labs of Joy Hirsch, Ph.D., professor of neuroradiology and psychology, and director of the fMRI Research Center and Eric Kandel, M.D., Howard Hughes Medical Institute senior investigator, Fred Kavli Professor and Director of the Kavli Institute for Brain Sciences.
The current findings extend on a previous Neuron paper (Dec 16, 2004) in which Drs. Etkin, Kandel and Hirsch found that anxious individuals show more activity in the amygdala, a central brain region involved in the processing of negative emotions, when unconsciously perceiving fearful stimuli (please click here to read the Columbia press release. When these stimuli were perceived consciously, however, the amygdalas of subject with both high and low levels of anxiety responded similarly.
Dr. Hirsch explained that this previous finding suggested that subjects were somehow able to control their conscious emotional responses, but that their unconscious responses may be more automatic. "Following the discovery of the amygdala's role in fear response, we decided to explore the finer points of the neurocircuitry of fear