Neurocircuits Commonly Involved in Psychiatric Disorders and Their Stimulation and Lesion Therapies

While the pathophysiology of psychiatric disorders remains incompletely understood, converging lines of evidence point to abnormalities in the prefrontal cortico-basal ganglia circuit. This chapter first addresses the functional anatomy of the regions most implicated in these disorders: orbital frontal cortex, ventral medial prefrontal cortex (vmPFC), dorsal anterior cingulate cortex, dorsolateral prefrontal cortex (DLPFC) and striatum. Next, it reviews the organization of specific white matter (WM) pathways that carry PFC fibres and are known to be abnormal in psychiatric disorders: the anterior limb of the internal capsule (ALIC), cingulum bundle, uncinate fasciculus, and corpus callosum. Finally, the chapter discusses the circuits most likely affected by neuromodulatory stimulation and lesion therapies for obsessive-compulsive disorder, addiction, depression and schizophrenia. These therapies include deep brain stimulation, with a focus on the ALIC and subcallosal WM; lesion therapies, including capsulotomy and cingulotomy; and transcranial magnetic stimulation and transcranial direct current stimulation in the DLPFC.