Increasingly, psychiatric changes are believed to not be attributed to a "center" of mood or behavior but, rather, are secondary to an imbalance in communication of multiple neuronal loops. However, the efficacy of DBS is typically attributed to a small generated electrical field that encompasses a very limited amount of cerebral tissue. Perhaps the stimulation generated at a certain target propagates downstream into the rest of the circuitry, gaining an amplified effect.
Currently, 6 targets for neuromodulation surgery have been published: the Cg25, the anterior internal capsule (AIC), the nucleus accumbens (NA), the ventral striatum (VS), the inferior thalamic peduncle (ITP), and the left vagus nerve. Each of these regions can be seen as nodes in the aforementioned circuitry. Putative modulation at these nodes is the basis of the current efforts investigating neuromodulation surgery for refractory psychiatric disease. The highlighted areas of Images 14, 15, 16, 17, 18, 19, 20, 21, 22, and 23 show how neuromodulation at each target may influence the aforementioned circuitry.
Brian H Kopell, MD,
Jerry L Halverson, MD
http://emedicine.medscape.com/article/1343677-overview