Functional Magnetic Resonance Imaging Studies of Emotional Processing in Normal and Depressed Patients: Effects of Venlafaxine

Background: Functional magnetic resonance imaging (fMRI) techniques were used to identify the neuralcircuitry underlying emotional processing in control and depressed subjects. Depressed subjects were studiedbefore and after treatment with venlafaxine. This new technique provides a method to noninvasively imageregional brain function with unprecedented spatial and temporal resolution. Method: Echo-planar imagingwas used to acquire whole brain images while subjects viewed positively and negatively valenced visualstimuli. Two control subjects and two depressed subjects who met DSM-IV criteria for major depressionwere scanned at baseline and 2 weeks later. Depressed subjects were treated with venlafaxine after the baselinescan. Results: Preliminary results from this ongoing study revealed three interesting trends in the data.Both depressed patients demonstrated considerable symptomatic improvement at the time of the second scan.Across control and depressed subjects, the negative compared with the positive pictures elicited greater globalactivation. In both groups, activation induced by the negative pictures decreased from the baseline scan tothe 2-week scan. This decrease in activation was also present in the control subjects when they were exposedto the positive pictures. In contrast, when the depressed subjects were presented with the positive picturesthey showed no activation at baseline, whereas after 2 weeks of treatment an area of activation emerged inright secondary visual cortex. Conclusion: While preliminary, these results demonstrate the power of usingfMRI to study emotional processes in normal and depressed subjects and to examine mechanisms of action ofantidepressant drugs.