Brain and Nerve Stimulation for Mood Enhancement

Enhancing brain activity and function is a very ancient practice which is usua lly accom plished by taking illegal drugs. Prescription medication is becoming more commonly used as a means of enhancing mood, and recently, it has become possible to modulate mood by applying magnetic (TMS) or electrica l current to the brain (tDCS, implanted electrodes) or by training the brain to work at predetermined oscillations (neurofeedback). A summary of the available neuromodulation techniques will be p resented associated with data from human subjects implanted with cortical and/or subcutaneous electrodes that demonstrate the potential for electrical neuro-enhancement. 1. The neurobiology of mood and emotion Mood can be defined as a relatively lasting emotional or affective state. Mood and emotion differ in that mood lasts longer than an emotion, is less specific, often less intense, and less likely to be triggered by a particular stimulus or event. Mood can be considered a normal physiological affective state generated by the brain. Mood disorders, a pathological emotional state, are disabling disturbances of mood or emotion. They most likely result from a failure to regulate mood (Johnstone et al, 2007). Major depression, for instance, can be described as a failure to regulate negative emotions. This is similar to fear, a physiological emotional state, and anxiety disorder, a pathological state, where a failure to regulate fear circuits leads to anxiety even though objective information about the outside world may indicate that the situation is not dangerous (LeDoux, 2003). Major depression is usually characterized by persistent mood states such as