For severe cases of obsessive compulsive disorder (OCD) that are resistant to pharmacotherapy, psychosurgery may be considered as an alternative treatment. In OCD there is an increase in activity in a neuronal circuit running from the frontal cortex to the cingulate gyrus, striatum, globus pallidus, thalamus and back to the frontal cortex. Surgical interruption of this loop by cingulotomy (destruction of 2–3 cm of white matter) at the anterior cingulate cortex disrupts transmission from the frontal cortex and reduces the symptoms of OCD.