A prosthetic motivational system

Changing patients’ behaviours is one of the most challenging parts of medical practice. It is hard to overstate how much of our disease burden would simply disappear if people would not smoke, drink alcohol in moderation or not at all, exercise regularly and eat healthy food. Perhaps a third of current cancer morbidity would cease to be, and far more of the cardiovascular morbidity. Of course, people will die from something in the end, but the gain in terms of productive life years would be enormous.

The reason why it’s so difficult to change people’s behaviour is that the reward systems of our brains are such powerful regulators of what we do, and it’s frustratingly difficult for any physician to override the patient’s urge to have his next cigarrette.

When there’s an important problem in the world, there’s also a bunch of scientists trying to solve it. Taking control of our motivational systems could transform our societies in profound ways. Can it be done?

Yes, says Christopher Harris. He is an old friend of mine and a neuroscientist at the university of Sussex. He is personally leading a campaign for the use of deep brain implants to control our reward systems – iPlants, in his coinage.

Deep brain stimulation is a technique similar to the pacemaker. Electrodes are placed in a specific brain region, which can then be activated by passing current through the electrode.

The neuroanatomy of reward is very well known. A small group of nerve cells in the midbrain, when stimulated, release dopamine throughout the entire prefrontal cortex, which is our decision generator. Deep brain stimulation to control reward would be very similar to its application against Parkinson’s disease, in which dopamine signalling is impaired, leading to symptoms of the motor system. Thus, the technology is tried and tested in humans.

The human motivational system has been shaped over millions of years of evolution to a degree of robustness, which is why we find it so difficult to change. Sweet food is an instant reward for most people, as are alcohol and many drugs. The modern society has developed spectacular shortcuts to dopamine release, with the unfortunate effect of making many people’s lives less functional. Obesity and addiction are long-term scourges caused by the inability to resist short-term dopamine stimulation. Here is a technology that could change all that.

But who will push the button?

Improperly used, a system like this might make the patient a slave to the man with the remote control. And supposing that an accountable system can be put in place to prevent that, there is the problem of how, exactly, to connect stimulation to the desirable behaviour. Christopher suggests:

Physical exercise can be motivated by repeatedly delivering rewarding brain stimulation (RBS) whenever an animal runs on a treadmill[10] or lifts a weight[11]. iPlant-driven exercise programs would apply the same principle to humans, for example by delivering RBS whenever the user pulls a stroke on a rowing machine or when pressure-sensitive shoe hit the ground during running (see top image). Every exercise program must have a strict time-limit agreed on in collaboration with a physician.

The science and technology of the iPlant is described in some detail on Christopher’s own web page. Whether it will be tried or not is an open question, but it’s not science fiction. All the technology is there, and it works in laboratory rats.

Whether or not the iPlant will be tried, it is clear that our increasing understanding of the brain is driving remarkable advances in technology to modulate and control its function. If we manage these developments properly, we will be able to solve very many problems. But the iPlant also highlights that these advances will bring ethical issues with them of which the general public needs to be aware.

Christopher has put up a few video clips on this topic, more can be found on youtube or on his website.

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