Neural explanations for OCD focus on neurotransmitters and brain structures. The neurotransmitter serotonin is believed to play a role in OCD. Lower levels of serotonin (possibly caused by the SERT gene) are associated with OCD. In terms of brain structures, the basal ganglia is involved in multiple processes, including the coordination of movement. Patients who suffer head injuries in this region often develop OCD-like symptoms, following their recovery.