What are the theories of OCD etiology (causes) with a focus on the neurobiology of the disorder (the pathology of the disorder OCD with an emphasis on the abnormalities of nervous system structures and function, including those neurotransmitter systems involved). the symptomatology of the disorder and its relationship with the neurotransmitters involved.anatomical changes seen with OCD, and what is the relationship between such changes and the symptoms seen in the disorder. how the dysregulation of neurotransmitter(s) and any anatomical changes would explain the physical signs and behavioral symptoms displayed by the individual diagnosed with OCD