MIAMI BEACH – Different brain regions appear to be responsible for processing emotional and cognitive stimuli during a common cognitive task used in psychiatric research, a new medical imaging study shows. Further, the activation of subcortical structures changed over time with repeated exposure to the task. The work has implications for researchers and clinicians involved with identifying new targets to treat mood disorders.
Functional magnetic resonance imaging (fMRI) gives detailed anatomic and physiologic data about the brain and has increasing importance for neural outcomes research, according to David Fleck, Ph.D., research associate professor with the Center for Imaging Research at the University of Cincinnati. His work, presented in a poster session, built on previous imaging research that showed differential activation of brain structures when emotional distraction interrupts a cognitive task.
Dr. David Fleck
Imaging offers investigators a “completely objective” measure of changes in brain function, and thus is an important tool in clinical trials for medications and treatments for mood disorders, Dr. Fleck said at a meeting of the American Society of Clinical Psychopharmacology, formerly known as the New Clinical Drug Evaluation Unit meeting. He noted that there can be variability in clinician assessments, and patients can both under- and overreport symptoms. Neuroimaging provides a means to measure absolute change in brain activity or structure, or both, over time.
Forty-one healthy subjects were recruited for the study, which obtained baseline, 1 week, and 8 week fMRI brain scans. During the scans, participants completed the Continuous Performance Task with Emotional and Neutral Distractor (CPT-END). This is a “visual oddball” task where participants are asked to differentiate a target – an image of a circle – from images of a square, and also from distracting images. Seventy percent of the time, subjects were shown a square. They saw the target circle 10% of the time and were presented either a neutral or an emotionally laden image, at a 10% rate for each image type, the remainder of the time.
Dr. Fleck and his colleagues at the University of Cincinnati identified the amygdala and the interior prefrontal gyrus as areas that showed more activation with both the neutral and the emotional distractors at baseline than with either the target circle or the square. However, at weeks 1 and 8, the emotional distractors elicited significantly more activation, particularly in the inferior frontal gyrus.
Deeper brain structures also showed differences between attentional and emotional stimuli, and activation changed over time: “Finally, targets elicited more caudate activation at baseline but not week 8 relative to both distractor types, while emotional distractors elicited more thalamic activation at week 8 but not baseline relative to neutrals and targets,” said Dr. Fleck and coinvestigators.
The study partly replicated and extended a study done more than a decade ago that looked at differential brain activation in cognitive attention versus emotional processes. This is important in mood disorder research, Dr. Fleck said in an interview. Bipolar disorder, for example, has significant cognitive and emotional components that contribute to the disease process. “It is hoped that this work will form the basis for a cognitive/emotional fMRI probe of pharmacological targets in mood disorders,” said Dr. Fleck and coinvestigators.
Dr. Fleck noted that advances in imaging technology since 2002 mean that the image analysis in this study could be much more fine-tuned in its identification of regions of interest, saying, “These findings will form the basis for further work characterizing the neurofunctional signature of mood-disordered patients over time.”
Dr. Fleck reported no conflicts of interest.
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