The Neuroanatomical, Neurophysiological and Neuropsychological aspects of Obsessive Compulsive Disorder.
Obsessive-compulsive disorder (OCD) is a psychiatric condition affecting about 2% of the population. Subjects with OCD typically suffer from recurring intrusive, unsettling thoughts and repetitive, ritualistic behaviors. This essay discusses the neuroanatomical, neurophysiological and neural psychological aspects of obsessive compulsive disorder. A range of studies have identified several regions within the brain thought to contribute to the disorder including the orbitofrontal cortex, important in reward based learning, the anterior cingulate cortex, important in error ...view middle of the document...
Thirdly they state that the themes of the obsessions and compulsions tend to be consistent across different cultures, fourth that some patients suffer from obsessions more predominantly than compulsions or vice versa, and lastly that symptoms can continue for a great length of time, giving the example of a “checker” who must continually check and re-check the same things for hours. These observations suggest that obsessive compulsive thoughts and behaviors exist alongside and as part of conscious awareness.
Research has provided several models of OCD implicating multiple regions of the brain and different circuits between these regions, as well as illuminating some of the cognitive impairments involved in the disorder. This essay is composed of three sections. The first will identify and explain the regions of the brain most researchers postulate are involved in OCD, the second will cover the functional neural circuits in which these regions act. The third section will review some of the cognitive deficits associated with OCD.
A number of neuroimaging studies between patients with OCD and healthy comparison subjects, lesion studies, and surgical studies have implicated several regions of the brain in the development of OCD. Also of use in determining the structures responsible for obsessive-compulsive symptoms are diseases processes known to affect different areas of the brain such as brain tumors or Huntington’s disease which produce similar symptoms to OCD (Neel, Stevens and Stewart, 2002). The regions of the brain most commonly associated with obsessive-compulsive disorder are the Prefrontal Cortex (PFC), especially the region known as the Orbitofrontal Cortex (OFC), the Caudate Nucleus within the Basal Nuclei (also known as the Basal Ganglia), the Anterior Cingulate Cortex (ACC), and the Thalamus.
The Orbitofrontal Cortex
The orbitofrontal cortex is a region of the prefrontal cortex located behind the frontal bone of the skull, just above the eyes. The OFC is theorized to be involved in decision making and expectation, reward-based learning and emotional processes, and the integration of these processes in social undertakings. In other words, it seems to be important in extrapolating the expected outcome of an action in a particular situation. Subjects suffering damage to their OFC experience a disruption of social and emotional behaviors (Huey et al., 2008). The prefrontal cortex as a whole may play a part in OCD with its role in the storage of behavioral sequence memories, and the reward or punishment corresponding with them. Huey et al. (2008) support the role of the PFC in OCD by noting that adults with damage to their prefrontal cortex tend to be inflexible, or ritualized, in their execution of plans compared to a healthy subject.
The Basal Nuclei
The basal ganglia, (more correctly known as the basal nuclei as the term ganglia refers to groups of neurons within the peripheral nervous system not the central nervous...