Overview
An iPlant is a brain implant that is in principle no different from today's deep brain stimulation (DBS) implants, but which has not yet been developed for human use. The implant would electronically regulate the release of monoamines in the brain, thus giving its user increased control over his or her motivation, mood, learning and creativity. Brain implants like this have been available for non-human animals for decades: by associating rewarding brain stimulation (RBS) with specific behaviours, they have been used to motivate rats and other animals to do heavy exercise and learn new skills (see references). Electronic regulation of monoamines could similarly help people perform difficult behaviours like physical exercise, learning or research (see iPlant programming). iPlants might also offer a more dynamic alternative to pharmacological modulators of monoamines, such as stimulants and antidepressants. The iPlant website promotes the ethical development of iPlants and public awareness of monoamine neuroscience and deep brain stimulation. More generally, it explores the prospect of personalized neuromodulation: what happens when people acquire increasingly better and more precise technological control over the chemistry of their own brains?
Recent developments
Reclaim, a deep brain stimulation (DBS) implant that improves behaviour and mood by modulating activity in the human reward system (ventral striatum) was FDA approved for distribution in the US in February of 2009. Researchers who apply DBS to the human reward system are aware that the procedure could generate pleasurable, rewarding brain stimulation (RBS), but avoid this by using stimulation parameters different from those applied in animal experiments involving RBS. Quoting one study: "Subjective effects were assessed using the morphine-benzedrine group subscale of the Addiction research centre inventory.. scores were 0 for all patients.. there was no 'liking'.. in contrast to findings reported by Heath, who observed that.. electrodes in subcortical structures induced extreme rewarding effects" (Schlaepfer et al 2008). But by not engaging in discussion and research into beneficial applications of RBS in human patients we are missing an important opportunity. Specifically, RBS could be used as an operant reinforcer to motivate difficult behaviours in patients lacking self-discipline. For example, RBS could be used to motivate heavy physical exercise, as previously demonstrated in rats (Burgess et al 1991, Garner et al 1991). At the time of writing DBS has been applied twice to treat obesity by suppressing hunger in the hypothalamus, with only limited success (eg Hamani et al 2008). RBS made conditional on the patient engaging in physical exercise might have a more reliable effect given the many health benefits of rigorous exercise. Conditional RBS could similarly be used to motivate learning and other behaviours that some individuals find exceedingly difficult, as previously demonstrated in rats (Hermez-Vasquez et al 2005). Conditional RBS would require a patient-doctor agreement to ensure that RBS is delivered if and only if the patient engages in desirable, pre-specified behaviours, such as the use of a rowing machine or an exercise cycle. Such an arrangement, where the patient voluntarily accepts restrictions on his/her ability to activate the Reclaim implant, raises a number of ethical issues that need to be articulated and discussed. There is also a practical question as to what stimulation parameters would best support RBS. This question could be addressed immediately if some of the patients who have received Reclaim implants would be willing to participate in a study to assess the effects of temporarily changing the stimulation parameters of their implants to match those used in animal experiments involving RBS.
Chris Dean
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