To support the concept of this specific circuitry underlying OCD is the finding that disruption of this pathway by surgical OSI-744 in vivo anterior internal capsulotomy and anterior cingulotomy enables improvements in OCD.39 A new model for OCD has been proposed by Huey and colleagues based on studies using functional MRI, MRI, and positron emission tomography.36 They examined patients with OCD who had other neurological disorders, and compared them to patients with idiopathic OCD. Some patients with “secondary” OCD had undergone surgery or deep brain stimulation believed to decrease hyperactivity in regions thought to provoke OCD. The group postulated

that three regions are implicated Inhibitors,research,lifescience,medical in both types of OCD: Inhibitors,research,lifescience,medical orbitofrontal cortex which directs appropriate behavior, the basal ganglia that acts

as a gate in connecting behaviors to subsequent reward, and the anterior cingulate region that modulates perception of which behavioral “choice” will result in reward. Patients with OCD from neurological disease had less anxiety with the compulsion than did those with the idiopathic form. Huey and Inhibitors,research,lifescience,medical colleagues postulated that the anxiety and impulse towards particular behaviors are requited only when the behavior is completed.36 Theories underlying the particular association between OCD and epilepsy include not only a possible shared mechanism, but an incidental OCD problem in patients with epilepsy.39 However, a compelling explanation for the OCS-epilepsy association is the interruption of a “pathological Inhibitors,research,lifescience,medical shared organization” when certain types of focal brain neurosurgery are performed, with the effect of causing regression of seizures, but also allowing latent OCD traits to appear.38,40 A sudden cessation of seizures after surgery might be seen as a form of “forced normalization.” 41,42 Hence the surgical removal Inhibitors,research,lifescience,medical of excitation, and preponderance of inhibition, would enable the occurrence

of psychiatric disorders, and have been termed the “forced normalization” concept and the “latent disease theory.” 41,42 Of note however, many postoperative TLE seizure patients never develop psychiatric problems. One of the components of OCD involving the perception of forced thoughts may occur from seizures themselves. In the classification of seizures, those seizures that involve part of the brain and which do not impair vigilance or memory, are whatever termed simple partial seizures. It has long been noted that obsessive thoughts can occur in the preictal period, be caused by simple partial seizures as an ictal phenomenon, or occur in the postictal period. Kroll and Drummond have suggested that the comorbidity of OCD and TLE might be due to kindling.15 The theory of kindling is that focal chemical or electrical brain stimulation can later result in a more persistent condition (eg, epilepsy). Some speculate that this might occur in the limbic circuit, and induce OCD problems. However, there is little evidence for this theory.