Localization of asymmetric brain function in emotion and depression

Herrington, J. D., Heller, W., Mohanty, A., Engels, A. S., Banich, M. T., Webb, A. G., & Miller, G. A. (2010). Localization of asymmetric brain function in emotion and depression. Psychophysiology, 47(3), 442-454. doi:10.1111/j.1469-8986.2009.00958.x

Localization of asymmetric brain function in emotion and depression

           I chose this article because I would like to learn more about how the brain is affected during different emotions and depression cases. I fell that emotions are important to everyday life and depression is most likely to affect someone we know or are close to at some point in our lives. Many previous studies by using EEG have shown that depression is linked to abnormal functioning in the asymmetries of the frontal cortex, these studies have failed to identify the specific location of the brain using fMRI and PET scans. The major goal of this study was to show a location of where the asymmetric abnormal functioning patterns occur in relation to emotion and depression.  This study hypothesized that emotional process are connected to asymmetric patterns of fMRI activity, particularly in the dorsolateral prefrontal cortex (DLPFC). They selected their participants by screening a large group of undergraduate using the Anhedonic Depression and Anxious Arousal scales of the Mood and Anxiety Symptom Questionnaire. By their scores they then divided them into the experimental and control groups. All of the participants scored below the 50^th percentile on the MASQ and the depressed scored in the 80^th percentile or above.  There were 28 participants in this study, 11 depressed individuals and 18 non-depressed control individuals. Then they gave the PSWQ and MASQ again prior to the fMRI the two groups did not vary on the PSWQ and MASQ but they did differ on the predicted direction on the MASQ- Anhedonic Depression scores. They completed the emotion-word Stroop task which included pleasant, unpleasant, and neutral words; there were 256 word stimuli included. The fMRI was a series of 370 images, but there was testing prior to the fMRI. The behavioral performance on the task had three hypotheses. First they hypothesized that both the experimental group, depressed individuals, and the control groups would take longer to respond to the emotional words than to the neutral words, Second they would have greater differentiation for unpleasant words than for pleasant words, and Third the depressed individuals would show a larger Stroop effect for unpleasant words than the control group. The results of their study found both of the groups showed a leftward lateralization for pleasant words in the DLPFC. In another DLPFC area the depressed individuals showed a more right lateralized activation than the control group, which replicated the findings previously by the EEG. The data found in this study confirmed that emotional stimulus processing and trait depression are linked to asymmetric brain functions in the distinct sub regions of the DLPFC. This study was very accurate to prove its hypothesis in finding the location in the frontal cortex most associated with emotion more specifically depression. I feel like this study was very interesting in showing the different regions affected most by emotion and depression. 

http://defd.colorado.edu/research/publications/LocalizationAsymmetricBrain.pdf