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This chapter summarizes techniques used for the placement of deep brain stimulation (DBS) electrodes. These procedures are performed primarily for the treatment of movement disorders such as Parkinson's disease, essential tremor, and dystonia. We describe radiologic atlas-based targeting using computed tomography and magnetic resonance imaging, physiological localization using microelectrode recordings, and macrostimulation techniques. We summarize the standard intraoperative surgical and mapping procedures used to localize the ventral intermediate nucleus of the thalamus (Vim), sub thalamic nucleus (STN), and globus pallidus pars interna (GPi).

This chapter reflects on the impact of brain stimulation on identity. Following substantial advances in our understanding of the brain, surgeons and neuroscientists have been able to develop powerful new medical interventions that aim to treat disease by modifying electrical activity in the brain. At present, Deep Brain Stimulation (DBS) is the most precise tool that we have at our disposal in this regard; it can target a cubic millimeter of brain tissue. In terms of precision, it stands in stark contrast to drugs that influence brain activity by affecting neurotransmitters across the brain. However, despite its precision, in some rare cases, DBS can have unintended side-effects, including behavioural and emotional changes. The possibility of controlling motivational and emotional states has intrigued scientists since the earliest days of invasive neurostimulation. This prospect raises profound ethical questions, regardless of whether such changes are intentional or an unintended side-effect of treatment. To what extent does it make sense to say that a medical intervention like DBS can change the recipient into “a different person”? The chapter then turns to concepts in moral philosophy, considering the nature of identity and the self.

As its name implies, the main characteristics of obsessive-compulsive disorder (OCD) are obsessions and/or compulsions. Different types of obsessions and compulsions make OCD a heterogeneous condition. Also, OCD exists on a continuum from mild cases to those with extremely severe and incapacitating manifestations generally not seen in other anxiety disorders. Clinical manifestations of OCD are striking and leave few people who observe them unimpressed. This is arguably due to the seriousness with which persons with OCD take their own obsessions and compulsions along with concurrent realization that these same obsessions and compulsions are senseless and should be gotten rid of. Indeed, there are few other examples in psychopathology where insight and deficiency of insight stand together, and where espousing and fighting the absurd are so intertwined. For all these reasons, OCD is often portrayed as a puzzling or intriguing disorder; in addition, it often represents a treatment challenge. Obsessive-compulsive disorder is probably the least controversial condition within the anxiety disorders because its clinical features are well described and relatively easily recognized and because hardly anyone doubts its existence as a psychopathological entity. What is controversial about OCD, however, is where it belongs and how it should be classified. This is a consequence of a number of features of OCD that make it look different from other anxiety disorders and of the close relationship that OCD has with some conditions outside of the realm of anxiety disorders. Listed below are a number of key questions about OCD…. 1. In view of its different clinical features and the vastly different severity of these features, should OCD be considered a unitary condition or divided into subtypes? 2. If OCD is to be divided into subtypes, on the basis of what criteria should it be done? Types of obsessions and compulsions, reasons for performing compulsions, severity of illness, degree of insight, age of onset, or something else? 3. Should neutralizing responses other than compulsions be given a more prominent role in the description and conceptualization of OCD? 4. How does insight contribute to the conceptualization of OCD? 5. What are the core features of OCD? Is OCD primarily an affective disorder, is it characterized by a primary disturbance in thinking, or is it essentially a disorder of repetitive behaviors?

Tourette’s syndrome (TS) is a neuropsychiatric disorder of childhood onset characterized by the presence of motor and vocal tics for a duration of at least 1 year. Tics are typically brief and stereotypical movements (eg, eye blinking, head jerks) or vocalizations (eg, throat clearing, grunting), but they can also be more complex movements involving multiple muscle groups and combinations of movements and sounds. There is a great range of tic severity. Tics can be so subtle or occur so infrequently as to be unnoticeable, even to the person with the tics. However, tics can also be so intense and frequent that they are readily noticeable by others, and they can be disruptive of daily activities. Indeed, in some cases (eg, severe head jerks), tics can cause pain or physical injury (eg, cervical disc and spine damage). Tics usually begin in childhood; the average age at diagnosis is 7 years. They reach peak severity in the early teen years and then lessen in intensity and frequency during young adulthood (Leckman et al., 2001). Tics wax and wane in severity, worsening with excitement and stress and improving during calm, focused activities. Coprolalia and its motor counterpart copropraxia (uttering obscene words or making obscene gestures, respectively) are uncommon symptoms, occurring in less than 10% of patients with TS and are not required for a diagnosis of TS (Robertson and Stern, 1998). Many patients describe a sensation or urge prior to tic occurrence, commonly referred to as a premonitory sensation or urge (Miguel et a1., 2000). Even though tics are considered involuntary, they can be voluntarily suppressed for short periods of time. Prevalence estimates of TS have varied and depend a great deal on the threshold for diagnosis and setting in which cases are identified. A review of the many epidemiologic studies suggests that 0.1% to 1% of people are affected with TS (Scahill et al., 2005). Despite this variability in specific rates, epidemiologic studies have consistently identified that males are more commonly affected than females, children are more frequently affected than adults, and that milder forms of TS are more common than severe forms.