Resumen
Parkinson's Disease (PD) is a movement disorder associated with untimely deterioration of neurons in the motor control areas of the brain, primarily the basal ganglia. Akinesia, or freezing gait, is a common symptom of PD. It is characterized by a progressive shortening of stride length, and eventually the total inability to initiate and sustain ambulation. This is one of the most debilitating symptoms of the disease, usually resulting in greatly reduced social and physical activity. Parkinson's symptoms are most commonly treated pharmacologically with variants of L-dopa, a chemical precursor of the neurotransmitter dopamine. L-dopa treatment can be quite effective for overcoming akinesia, but it typically has at least two undesirable characteristics: its effects are widely variable throughout the course of the day; and over time increasingly more severe dyskinesia may result, often to the point of being as difficult to manage as the akinesia itself, and sometimes resulting in profound weight loss due to constant exertion.

Resumen
It is not surprising that phobia treatment would be one of the first successful mental health uses for virtual reality (VR). The sense of being immersed in another setting is particularly valuable in exposure therapy, a treatment technique for phobias. Exposure therapy involves subjecting the patient to anxiety-producing stimuli while allowing the anxiety to attenuate. These stimuli have traditionally been generated by presenting the patient with actual physical situations or by having the patient imagine the stimulus. VR allows a third option of exposure in a virtual setting that is safer, less embarrassing, and less costly then reproducing the real-world situations and more realistic than imagining the danger. An additional advantage of computer-controlled stimuli is that the patient can more easily regulate the level of the induced anxiety by modifying the parameters of the world to reduce or increase fear to match individual tolerance. All phobia treatment studies to date have used a headset to reproduce the feeling of presence in an anxiety-producing situation