Area 25 - A Wiring Diagram in the Brain for Depression

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When Helen Mayberg started curing depression by stimulating a previously unknown neural junction box in a brain area called Brod­mann’s area 25—discovered through 20 years of dogged research—people asked her where she was going to look next. Her reaction was, "What do you mean, Where am I going to look next? I’m going to look more closely here!"

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Working with fellow imaging experts Heidi Johansen-Berg and Tim Behrens of the University of Oxford and others, Mayberg used DTI to produce detailed images of area 25’s "tractography," the layout of the white matter tracts that connect disparate brain regions. They identified five connective tracts that run through this pea-size region, carrying neural traffic among five vital areas: the amygdala, a deep-brain area that mode­rates fear and other emotions; the orbi­tofrontal and medial frontal cortices, two poorly understood areas that ap­pear to be significant in expectation, reward processing, error assessment, learning and decision making; the hippocampus, vital to memory; and the hypothalamus, which helps to regulate stress and arousal.

The refined imaging of these tracts does more than just confirm Mayberg’s previous work identifying area 25 as a junction box. It also gives her a map that provides diagnostic and targeting information for DBS treatments of the area. As she expected, the locations of those tracts varies among individuals. "And this variation," Mayberg says, "along with variations in the nature of different patients’ depression, probably explains why some patients respond better than others. Because the location varies, we’re not hitting all five tracts the same way in every patient."

http://www.scientificamerican.com/article.cfm?id=insights-into-the-brains-circuitry