• Sameer A Sheth, Robert McGovern, and Charles B Mikell.
• Neurosurgery. 2015 Aug 1;62 Suppl 1:208.

IntroductionNeurosurgical treatments for refractory psychiatric disorders such as obsessive-compulsive disorder (OCD) are rapidly increasing. The National Institute of Mental Health has reclassified mental health disorders according to neurobiological mechanisms rather than traditional diagnostic categories. According to this Research Domain Criteria matrix, OCD would be classified as a disorder of cognitive control, with additional contributions from other axes. We bring together the neuroscientific literature on cognitive control and dorsal anterior cingulate cortex (dACC) function with human functional MRI (fMRI) and EEG data to demonstrate (1) the central role of the dACC in cognitive control; and (2) the relevance of this framework for the neurosurgical treatment of OCD.MethodsTwelve healthy controls underwent fMRI using a cognitive interference task. Six patients with OCD and chronic pain underwent cingulotomy, with fMRI using the same task before and after the lesion. Twenty separate OCD patients undergoing chronic repetitive transcranial magnetic stimulation (rTMS) treatment performed the same task with EEG recordings at 2-week intervals.ResultsfMRI reliably activated the dACC in control subjects and patients preoperatively (Figure 1). Behavioral analysis demonstrated altered measures of cognitive control following a dACC lesion, including longer reaction times and abolishment of conflict adaptation effects. EEG measures of cognitive control, including the N2, error-related negativity, and frontal midline theta power, were abnormally elevated in OCD and diminished toward normal levels with chronic rTMS (Figure 2).ConclusionWe collect a breadth of data to illustrate the following points: (1) the dACC is central to cognitive control; (2) cognitive control is dysfunctional in OCD; (3) neuromodulatory treatment of OCD normalizes physiological measures of cognitive control. We discuss these findings within the framework of the recently proposed Expected Value of Control (EVC) model of dACC function. The development of neurobiological conceptualizations such as these will be critical to the advancement of our network-level understanding of neuropsychiatric disorders and their neurosurgical treatments.

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