The Future of the Mind (31 page)

To see how widespread this problem has become, consider that by 2007, thirteen million Americans aged twelve or over (or 5 percent of the entire teen and adult population of the United States) had tried or become addicted to methamphetamines. Drug addiction not only destroys entire lives, it also systematically destroys the brain. MRI scans of the brains of meth addicts show an 11 percent reduction in the size of the limbic system, which processes emotions, and an 8 percent loss of tissue in the hippocampus, which is the gateway for memory. MRI scans show that the damage in some ways is comparable to that found in Alzheimer’s patients. But no matter how much meth destroys the brain, addicts crave it because its high is up to twelve times the rush caused by eating a delicious meal or even having sex.

Basically, the “high” of drug addiction is due to the drug’s hijacking of the brain’s own pleasure/reward system located in the limbic system. This pleasure/reward circuit is very primitive, dating back millions of years in evolutionary history, but it is still extremely important for human survival because it rewards beneficial behavior and punishes harmful acts. Once this circuit is taken over by drugs, however, the result can be widespread havoc. These drugs first penetrate the blood-brain barrier and then cause the overproduction of neurotransmitters like dopamine, which then floods the nucleus accumbens, a tiny pleasure center located deep in the brain near the amygdala. The dopamine, in turn, is produced by certain brain cells in the ventral tegmental area, called VTA cells.

All drugs basically work the same way: by crippling the VTA–nucleus accumbens circuit, which controls the flow of dopamine and other neurotransmitters to the pleasure center. Drugs differ only in the way in which this process takes place. There are at least three main drugs that stimulate the pleasure center of the brain: dopamine, serotonin, and noradrenaline; all of them give feelings of pleasure, euphoria, and false confidence, and also produce a burst of energy.

Cocaine and other stimulants, for example, work in two ways. First, they directly stimulate the VTA cells to produce more dopamine, hence causing excess dopamine to flood into the nucleus accumbens. Second, they prevent the VTA cells from going back to their “off” position, thus keeping them continually producing dopamine. They also impede the uptake of serotonin and noradrenaline. The simultaneous flooding of neural circuits from all three of these neurotransmitters, then, creates the tremendous high associated with cocaine.

Heroin and other opiates, by contrast, work by neutralizing the cells in the VTA that can reduce the production of dopamine, thus causing the VTA to overproduce dopamine.

Drugs like LSD operate by stimulating the production of serotonin, inducing a feeling of well-being, purpose, and affection. But they also activate areas of the temporal lobe involved in creating hallucinations. (Only fifty micrograms of LSD can cause hallucinations. LSD binds so tightly, in fact, that further increasing the dosage has no effect.)

Over time, the CIA came to realize that mind-altering drugs were not the magic bullet they were looking for. The hallucinations and addictions that accompany these drugs made them too unstable and unpredictable, and they could cause more trouble than they were worth in delicate political situations.

(It should be pointed out that just in the last few years, MRI brain scans of drug addicts have indicated a novel way to possibly cure or treat some forms of addiction. By accident, it was noticed that stroke victims who have damage to the insula [located deep in the brain, between the prefrontal cortex and the temporal cortex] have a significantly easier time quitting smoking than the average smoker. This result has also been verified among drug abusers using cocaine, alcohol, opiates, and nicotine. If this result holds up, it might mean that one may be able to dampen the activity of the insula using electrodes or magnetic stimulators and hence treat addiction. “This is the
first time we’ve shown anything like this, that damage to a specific brain area could remove the problem of addiction entirely. It’s mind-boggling,” says Dr. Nora Volkow, director of the National Institute on Drug Abuse. At present, no one knows how this works, because the insula is involved in a bewildering variety of brain functions, including perception, motor control, and self-awareness. But if this result bears out, it could change the entire landscape of addiction studies.)

PROBING THE BRAIN WITH OPTOGENETICS

These mind-control experiments were done mainly in an era when the brain was largely a mystery, with hit-or-miss methods that often failed. However, because of the explosion in devices that can probe the brain, new opportunities have arisen that will both help us understand the brain as well as possibly teach us how to control it.

Optogenetics, as we have seen, is one of the fastest-developing fields in science today. The basic goal is to identify precisely which neural pathway corresponds to which mode of behavior. Optogenetics starts with a gene called opsin, which is quite unusual because it is sensitive to light. (It is believed that the appearance of this gene hundreds of millions of years ago was responsible for creating the first eye. In this theory, a simple patch of skin sensitive to light due to opsin evolved into the retina of the eye.)

When the opsin gene is inserted into a neuron and exposed to light, the neuron will fire on command. By flipping a switch, one can instantly recognize the neural pathway for certain behaviors because the proteins manufactured by opsin conduct electricity and will fire.

The hard part, though, is to insert this gene into a single neuron. To do this, one uses a technique borrowed from genetic engineering. The opsin gene is inserted into a harmless virus (which has had its bad genes removed), and, using precision tools, it is then possible to apply this virus to a single neuron. The virus then infects the neuron by inserting its genes into the genes of the neuron. Then, when a light beam is flashed onto neural tissue, the neuron is turned on. In this way, one can establish the precise pathway that certain messages take.

Not only does optogenetics identify certain pathways by shining a light beam on them, it also enables scientists to control behavior. Already this
method has been a proven success. It was long suspected that a simple neural circuit must be responsible for fruit flies escaping and flying away. Using this method, it was possible to finally identify the precise pathway behind the quick getaway. By simply shining a beam onto these fruit flies, they bolt on demand.

Scientists are also now able to make worms stop wiggling by flashing light, and in 2011 yet another breakthrough was made. Scientists at Stanford were able to insert the opsin gene into a precise region of the amygdala of mice. These mice, which were specially bred to be timid, cowered in their cage. But when a beam of light was flashed into their brains, the mice suddenly lost their timidity and began to explore their cage.

The implications are enormous. While fruit flies may have simple reflex mechanisms involving a handful of neurons, mice have complete limbic systems with counterparts in the human brain. Although many experiments that work with mice do not translate to human beings, this still holds out the possibility that scientists may one day find the precise neural pathways for certain mental illnesses, and then be able to treat them without any side effects. As Dr. Edward Boyden of MIT says, “
If you want to turn off a brain circuit and the alternative is surgical removal of a brain region, optical fiber implants might seem preferable.”

One practical application is in treating Parkinson’s disease. As we have seen, it can be treated by deep brain stimulation, but because the positioning of electrodes in the brain lacks precision, there is always the danger of strokes, bleeding, infections, etc. Deep brain stimulation can also cause side effects such as dizziness and muscle contractions, because the electrodes can accidentally stimulate the wrong neurons. Optogenetics may improve deep brain stimulation by identifying the precise neural pathways that are misfiring, at the level of individual neurons.

Victims of paralysis might also benefit from this new technology. As we saw in
Chapter 4
, some paralyzed individuals have been hooked up to a computer in order to control a mechanical arm, but because they have no sense of touch, they often wind up dropping or crushing the object they wish to grab. “
By feeding information from sensors on the prosthetic fingertips directly back to the brain using optogenetics, one could in principle provide a high-fidelity sense of touch,” says Dr. Krishna Shenoy of Stanford.

Optogenetics will also help clarify which neural pathways are involved
with human behavior. In fact, plans have already been drawn up to experiment with this technique on human brains, especially with regard to mental illness. There will be hurdles, of course. First, the technique requires opening up the skull, and if the neurons that one wishes to study are located deep inside the brain, the procedure will be even more invasive. Lastly, one has to insert tiny wires into the brain that can shine a light on this modified neuron so that it triggers the desired behavior.

Once these neural pathways have been deciphered, you can also stimulate them, making animals perform strange behaviors (for example, mice will run around in circles). Although scientists are just beginning to trace the neural pathways governing simple animal behaviors, in the future they should have an encyclopedia of such behaviors, including those of humans. In the wrong hands, however, optogenetics could potentially be used to control human behavior.

In the main, the benefits of optogenetics greatly outweigh its drawbacks. It can literally reveal the pathways of the brain in order to treat mental illness and other diseases. This may then give scientists the tools by which to repair the damage, perhaps curing diseases once thought to be incurable. In the near future, then, the benefits are all positive. But further in the future, once the pathways of human behaviors are also understood, optogenetics could also be used to control or at least modify human behavior as well.

MIND CONTROL AND THE FUTURE

In summary, the use of drugs and hypnotism by the CIA was a flop. These techniques were too unstable and unpredictable to be of any use to the military. They can be used to induce hallucinations and dependency, but they have failed to cleanly erase memories, make people more pliant, or force people to perform acts against their will. Governments will keep trying, but the goal is elusive. So far, drugs are simply too blunt an instrument to allow you to control someone’s behavior.

But this is also a cautionary tale. Carl Sagan mentions one nightmare scenario that might actually work. He envisions a dictator taking children and putting electrodes into their “pain” and “pleasure” centers. These electrodes are then connected wirelessly to computers, so that the dictator can control his subjects with the push of a button.

Another nightmare might involve probes placed in the brain that could override our wishes and seize control of our muscles, forcing us to perform tasks we don’t want to do. The work of Dr. Delgado was crude, but it showed that bursts of electricity applied to motor areas of the brain can overrule our conscious thoughts, so that our muscles are no longer under our control. He was able to identify only a few behaviors in animals that could be controlled with electric probes. In the future, it may be possible to find a wide variety of behaviors that can be controlled electronically with a switch.

If you are the person being controlled, it would be an unpleasant experience. Although you may think you are master of your own body, your muscles would actually fire without your permission, so you would do things against your will. The electric impulse being fed into your brain could be larger than the impulses you consciously send into your muscles, so that it would appear as if someone had hijacked your body. Your own body would become a foreign object.

In principle, some version of this nightmare might be possible in the future. But there are several factors that may prevent this as well. First, this is still an infant technology and it is not known how it will be applied to human behavior, so there is still plenty of time to monitor its development and perhaps create safeguards to see that it is not misused. Second, a dictator might simply decide that propaganda and coercion, the usual methods of controlling a population, are cheaper and more effective than putting electrodes into the brains of millions of children, which would be costly and invasive. And third, in democratic societies, a vigorous public debate would probably emerge concerning the promise and limitations of this powerful technology. Laws would have to be passed to prevent the abuse of these methods without impairing their ability to reduce human suffering. Soon science will give us unparalleled insight into the detailed neural pathways of the brain. A fine line has to be drawn between technologies that can benefit society and technologies that can control it. And the key to passing these laws is an educated, informed public.

But the real impact of this technology, I believe, will be to liberate the mind, not enslave it. These technologies can give hope to those who are trapped in mental illness. Although there is as yet no permanent cure for mental illness, these new technologies have given us deep insight into how such disorders form and how they progress. One day, through genetics,
drugs, and a combination of high-tech methods, we will find a way to manage and eventually cure these ancient diseases.

One of the recent attempts to exploit this new knowledge of the brain is to understand historical personalities. Perhaps the insights from modern science can help explain the mental states of those in the past.

And one of the most mystifying figures being analyzed today is Joan of Arc.

Lovers and madmen have such seething brains.…

The lunatic, the lover, and the poet

Are of imagination all compact.

—
WILLIAM SHAKESPEARE
,
A MIDSUMMER NIGHT
’
S DREAM