The Emotional Pathways of Bipolar Disorder

Amber Badgerow

November 13, 2011

PSY 213

John Olmsted

The Emotional Pathways of Bipolar Disorder

Question: Bipolar is a tragic, debilitating disorder that is distinguished by the fluctuation between emotional extremes of depression and mania, in the case of Bipolar I Disorder, or hypomania in the case of Bipolar II Disorder. Is there an abnormality of the brain’s emotional pathway, specifically in the amygdala and prefrontal cortex, in those with Bipolar Disorder?

Prediction: The brain’s emotional pathway in those with Bipolar Disorder may be hyperactive in the in amygdala, or may have irregular connections, or may be hypoactive in certain regions, specifically the prefrontal cortex that cognitively regulates emotion.

Article 1: “Functional Magnetic Resonance Imaging Brain Activation in Bipolar Mania: Evidence for Disruption of the Ventrolateral Prefrontal-Amygdala Emotional Pathway”

This article discusses the study by Stephen M. Strakowski, James C. Eliassen, Martine Lamy, Michael A. Cerullo, Jane B. Allendorfer, Michelle Madore, Jing-Huei Lee, Jeffrey A. Welge, Melissa P. DelBello, David E. Fleck, and Caleb M. Adler to detect irregularities in the emotional system of patients with manic bipolar using functional magnetic resonance imaging (fMRI). Previous research indicated that a ventrolateral prefrontal network regulated external emotional stimulus processing and Strakowski et al. chose to study this network. Forty patients with bipolar mania and thirty-eight healthy subjects performed a Continuous Performance Task with Emotional and Neutral Distracters (CPT-END) while brain scans were taken. Patients with bipolar mania exhibited dulled activation to emotional and neutral stimulus in the right lingual gyrus, the medial thalamus, the left ventrolateral prefrontal cortex, the left amygdala, the right parahippocampus, and the precuneus compared to the control group. However, they exhibited hyperactivity to "targets"- colored circles that required participants to press a button different from the one pressed for emotional or neutral pictures- in the right inferior frontal gyrus, the left fusiform gyrus, the right superior frontal gyrus, the right parahippocampus, the right putamen, and the right amygdala. This suggested that patients with bipolar enlisted that help of other brain regions for the task more than the healthy subjects did. These results indicated that the ventrolateral prefrontal-amygdala emotional network does not function properly during bipolar mania and causes a loss of regulation of the limbic brain by the ventral prefrontal cortex.

Article 2: “Abnormally increased effective connectivity between parahippocampal gyrus and ventromedial prefrontal regions during emotion labeling in bipolar disorder”

This article was written by Jorge R.C. Almeida, Andrea Mechelli, Stefanie Hassel, Amelia Versace, David J. Kupfer, and Mary L. Phillips. It reviews their study to examine remaining irregularities in the effective connectivity of the ventromedial and dorsal/lateral neural systems associated with mood modulation in patients with subsiding bipolar disorder. They used dynamic causal modeling (DCM) and fMRI to determine effective connectivity while participants (twenty-one patients with bipolar disorder and twenty-five healthy subjects) viewed mild and intense happy and neutral facial emotions. Patients with bipolar disorder exhibited reduced activity in the right parahippocampal gyrus with intense and mild happy faces compared to the healthy control group. They also showed decreased activity in the right dorsolateral prefrontal cortex in response to all emotional faces. Greater effective connectivity was seen in patients with bipolar between the right parahippocampal gyrus, which has connections to the amygdala, and the right subgenual anterior cingulate gyrus, associated with depression, when identifying emotions of happy and neutral facial expressions. These results indicated that patients with bipolar disorder have a dysfunctional ventromedial prefrontal network- associated with the early evaluation of stimulus, heightened encoding, and the automatic modulation of emotion- which may be a cause of the mood dysregulation observed in bipolar disorder.

Source Validity:

Both sources had small sample groups and had a mix of medicated and non-medicated patients with bipolar. The first study only had patients that were manic and the second had only had patients that were in remission. However, they also controlled for age, race, IQ, education, handedness, and other medical conditions, specifically psychological. Also, both sources were reliable and referenced previous studies to support their results. The second article was a little older, but still presented results that are concurrent with most other studies. One of the factors that lessened the reliability of the studies mentioned above was the lack of repeated studies that used the same task to find abnormalities in the emotional system of patients with bipolar disorder.

Reflection on Hypothesis:

The research supported my hypothesis that there may be irregular connectivity in the emotional system in people with bipolar disorder. However, increased and decreased activity in certain brain regions that are involved in processing and regulating emotion depends on the task participants perform. In some studies not mentioned in this article the amygdala showed increased activity, but in the first article discussed there was decreased activity. The research did support my prediction that the prefrontal cortex may show decreased activity, but more studies need to be reviewed to ensure validity. Many other studies have examined emotional pathways in euthymic bipolar, but the above articles were chosen because I wanted to concentrate on people with manic bipolar.

Works Cited:

Strakowski Stephen M., Eliassen James C., et al. “Functional Magnetic Resonance Imaging

Brain Activation in Bipolar Mania: Evidence for Disruption of the Ventrolateral Prefrontal

Amygdala Emotional Pathway.” Biological Psychiatry 69.4 (2011): 381-388. Elsevier Inc.

ScienceDirect. Web. Nov. 13, 2011.

http://0-www.sciencedirect.com.library.pcc.edu/science/article/pii/S000632231000956X

Almeida Jorge R.C., Mechelli Andrea, Hassel Stefanie, Versace Amelia, Kupfer David

J., and Phillips Mary L. “Abnormally increased effective connectivity between

parahippocampal gyrus and ventromedial prefrontal regions during emotion labeling

in bipolar disorder.” Psychiatry Research: Neuroimaging 174.3 (2009): 195-201.

Elsevier Ireland Ltd. ScienceDirect. Web. Nov. 13, 2011.

< http://0-www.sciencedirect.com.library.pcc.edu/science/article/pii/S0925492709001176>