Deep brain stimulation (DBS) of the globus pallidus interna and subthalamic nucleus has restored some degree of motor control in many patients in advanced stages of Parkinson’s disease. DBS has also been used to treat dystonia, essential tremor (progressive neurological condition causing trembling), chronic pain, obsessive-compulsive disorder, Tourette’s syndrome, major depressive disorder, obesity, cerebral palsy, and the minimally conscious state. Although the underlying mechanisms of the technique are still not clear, DBS can modulate underactive or overactive neural circuits and restore (...) disrupted communication between and among groups of neurons in interacting regions of the brain. This can control and relieve many symptoms associated with a range of neurological and psychiatric disorders.But the procedures of implanting and stimulating the electrodes are brain-invasive and entail significant risks. Some patients receiving DBS have experienced intracerebral hemorrhage, infection, cognitive disturbances such as impulsive behavior, and affective disturbances such as mania. It is not known whether continuous electrical stimulation of the brain would reshape synaptic connectivity and permanently alter neural circuits in ways that may not be salutary. The risk of these effects indicates that DBS should be used only when a patient’s condition is refractory to all other interventions and when there is a high probability that the technique will benefit the patient and improve his or her quality of life. If a patient’s quality of life is poor and all other treatment options have been exhausted, then the likelihood of benefit can justify physicians’ exposing patients to some risk. The clinical and ethical significance of the risk in DBS underscores the obligation of physicians to obtain fully informed consent from patients undergoing the procedure. (shrink)

Deep-brain stimulation has been used to treat advanced Parkinson disease and other neurological and psychiatric disorders that have not responded to other treatments. While deep-brain stimulation can modulate overactive or underactive regions of the brain and thereby improve motor function, it can also cause changes in a patient’s thought and personality. This paper discusses the trade-offs between the physiological benefit of this technique and the potential psychological harm.

Revolutions in semiconductor device miniaturization, bioelectronics, and applied neural control technologies are enabling scientists to create machine-assisted minds, science fiction's “cyborgs.” In a paper published in 1999, we sought to draw attention to the advances in prosthetic devices, to the myriad of artificial implants, and to the early developments of this technology in cochlear and retinal implants. Our concern, then and now, was to draw attention to the ethical issues arising from these innovations. Since that time, breakthroughs have occurred at (...) a breathtaking pace. Scientists, researchers, and engineers using differing methodologies are pursuing the possibilities of direct interfaces between brains and machines. Technological innovations as such are neither good nor evil; it is the uses devised for them that create moral implications. As there can be ethical problems inherent in the proper human uses of technologies and because brain chips are a very likely future technology, it is prudent to formulate policies and regulations that will mitigate their ill effects before the technologies are widespread. Unlike genetic technologies, which have received widespread scrutiny within the scientific community, national governments, and international forums, brain–machine interfaces have received little social or ethical scrutiny. However, the potential of this technology to change and significantly affect humans is potentially far greater than that of genetic enhancements, because genetic enhancements are inherently limited by biology and the single location of an individual, whereas hybrids of human and machine are not so restricted. Today, intense interest is focused on the development of drugs to enhance memory; yet, these drugs merely promise an improvement of normal memory, not the encyclopedic recall of a computer-enhanced mind combined with the ability to share information at a distance. The potential of brain chips for transforming humanity are astounding. This paper describes advances in hybrid brain–machine interfaces, offers some likely hypotheses concerning future developments, reflects on the implications of combining cloning and transplanted brain chips, and suggests some potential methods of regulating these technologies. (shrink)