The Future of the Mind (33 page)

Recently, brain scans of schizophrenics taken while they were having auditory hallucinations have helped explain this ancient disorder. For example, when we silently talk to ourselves, certain parts of the brain light up on an MRI scan, especially in the temporal lobe (such as in Wernicke’s area). When a schizophrenic hears voices, the very same areas of the brain light up. The brain works hard to construct a consistent narrative, so schizophrenics try to make sense of these unauthorized voices, believing they originate from strange sources, such as Martians secretly beaming thoughts into their brains. Dr. Michael Sweeney of Ohio State writes, “
Neurons wired for the sensation of sound fire on their own, like gas-soaked rags igniting spontaneously in a hot, dark garage. In the absence of sights and sounds in the surrounding environment, the schizophrenic’s brain creates a powerful illusion of reality.”

Notably, these voices seem to be coming from a third party, who often gives the subject commands, which are mostly mundane but sometimes violent. Meanwhile, the simulation centers in the prefrontal cortex seem to be on automatic pilot, so in a way it’s as though the consciousness of a schizophrenic is running the same sort of simulations we all do, except they’re done without his permission. The person is literally talking to himself without his knowledge.

HALLUCINATIONS

The mind constantly generates hallucinations of its own, but for the most part they are easily controlled. We see images that don’t exist or hear spurious sounds, for example, so the anterior cingulate cortex is vital to distinguish the real from the manufactured. This part of the brain helps us distinguish between stimuli that are external and those that are internally generated by the mind itself.

However, in schizophrenics, it is believed that this system is damaged, so that the person cannot distinguish real from imaginary voices. (The anterior cingulate cortex is vital because it lies in a strategic place, between the prefrontal cortex and the limbic system. The link between these two areas is one of the most important in the brain, since one area governs rational thinking, and the other emotions.)

Hallucinations, to some extent, can be created on demand. Hallucinations occur naturally if you place someone in a pitch-black room, an isolation chamber, or a creepy environment with strange noises. These are examples of “our eyes playing tricks on us.” Actually, the brain is tricking itself, internally creating false images, trying to make sense of the world and identify threats. This effect is called “pareidolia.” Every time we look at clouds in the sky, we see images of animals, people, or our favorite cartoon characters. We have no choice. It is hardwired into our brains.

In a sense, all images we see, both real and virtual, are hallucinations, because the brain is constantly creating false images to “fill in the gaps.” As we’ve seen, even real images are partly manufactured. But in the mentally ill, regions of the brain such as the anterior cingulate cortex are perhaps damaged, so the brain confuses reality and fantasy.

THE OBSESSIVE MIND

Another disorder in which drugs may be used to heal the mind is OCD (obsessive-compulsive disorder). As we saw earlier, human consciousness involves mediating between a number of feedback mechanisms. Sometimes, however, the feedback mechanisms are stuck in the “on” position.

One in forty Americans suffers from OCD. Cases can be mild, so that, for example, people have to constantly go home to check that they locked
the door. The detective Adrian Monk on the TV show
Monk
has a mild case of OCD. But OCD can also be so severe that people compulsively scratch or wash their skin until it is left bleeding and raw. Some people with OCD have been known to repeat obsessive behaviors for hours, making it difficult to keep a job or have a family.

Normally these types of compulsive behaviors, in moderation, are actually good for us, since they help us keep clean, healthy, and safe. That is why we evolved these behaviors in the first place. But someone with OCD cannot stop this behavior, and it spirals out of control.

Brain scans are now revealing how this takes place. They show that at least three areas of the brain that normally help us keep ourselves healthy get stuck in a feedback loop. First, there is the orbitofrontal cortex, which we saw in
Chapter 1
can act as a fact-checker, making sure that we have properly locked the doors and washed our hands. It tells us, “Hmm, something is wrong.” Second, the caudate nucleus, located in the basal ganglia, governs learned activities that are automatic. It tells the body to “do something.” And finally, we have the cingulate cortex, which registers conscious emotions, including discomfort. It says, “I still feel awful.”

Psychiatry professor Jeffrey Schwartz of UCLA has tried to put this all together to explain how OCD gets out of hand. Imagine you have the urge to wash your hands. The orbitofrontal cortex recognizes that something is wrong, that your hands are dirty. The caudate nucleus kicks in and causes you to automatically wash your hands. Then the cingulate cortex registers satisfaction that your hands are clean.

But in someone with OCD, this loop is altered. Even after he notices that his hands are dirty and he washes them, he still has the discomforting feeling that something is wrong, that they are still dirty. So he is stuck in a feedback loop that won’t stop.

In the 1960s, the drug clomipramine hydrochloride began to give OCD patients some relief. This and other drugs developed since then raise levels of the neurotransmitter serotonin in the body. They can reduce symptoms of OCD by as much as 60 percent in clinical trials. Dr. Schwartz says, “
The brain’s gonna do what the brain’s gonna do, but you don’t have to let it push you around.” These drugs are certainly not a cure, but they have brought some relief to the sufferers of OCD.

BIPOLAR DISORDER

Another common form of mental illness is bipolar disorder, in which a person suffers from extreme bouts of wild, delusional optimism, followed by a crash and then periods of deep depression. Bipolar disorder also seems to run in families and, curiously, strikes frequently in artists; perhaps their great works of art were created during bursts of creativity and optimism. A list of creative people who were afflicted by bipolar disorder reads like a Who’s Who of Hollywood celebrities, musicians, artists, and writers. Although the drug lithium seems to control many of the symptoms of bipolar disorder, the causes are not entirely clear.

One theory states that bipolar disorder may be caused by an imbalance between the left and right hemispheres. Dr. Michael Sweeney notes, “
Brain scans have led researchers to generally assign negative emotions such as sadness to the right hemisphere and positive emotions such as joy to the left hemisphere. For at least a century, neuroscientists have noticed a link between damage to the brain’s left hemisphere and negative moods, including depression and uncontrollable crying. Damage to the right, however, has been associated with a broad array of positive emotions.”

So the left hemisphere, which is analytical and controls language, tends to become manic if left to itself. The right hemisphere, on the contrary, is holistic and tends to check this mania. Dr. V. S. Ramachandran writes, “
If left unchecked, the left hemisphere would likely render a person delusional or manic.… So it seems reasonable to postulate a ‘devil’s advocate’ in the right hemisphere that allows ‘you’ to adopt a detached, objective (allocentric) view of yourself.”

If human consciousness involves simulating the future, it has to compute the outcomes of future events with certain probabilities. It needs, therefore, a delicate balance between optimism and pessimism to estimate the chances of success or failures for certain courses of action.

But in some sense, depression is the price we pay for being able to simulate the future. Our consciousness has the ability to conjure up all sorts of horrific outcomes for the future, and is therefore aware of all the bad things that could happen, even if they are not realistic.

It is hard to verify many of these theories, since brain scans of people who are clinically depressed indicate that many brain areas are affected. It is difficult to pinpoint the source of the problem, but among the clinically
depressed, activity in the parietal and temporal lobes seems to be suppressed, perhaps indicating that the person is withdrawn from the outside world and living in their own internal world. In particular, the ventromedial cortex seems to play an important role. This area apparently creates the feeling that there is a sense of meaning and wholeness to the world, so that everything seems to have a purpose. Overactivity in this area can cause mania, in which people think they are omnipotent.
Underactivity in this area is associated with depression and the feeling that life is pointless. So it is possible that a defect in this area may be responsible for some mood swings.

A THEORY OF CONSCIOUSNESS AND MENTAL ILLNESS

So how does the space-time theory of consciousness apply to mental illness? Can it give us a deeper insight into this disorder? As we mentioned before, we define human consciousness as the process of creating a model of our world in space and time (especially the future) by evaluating many feedback loops in various parameters in order to achieve a goal.

We have proposed that the key function of human consciousness is to simulate the future, but this is not a trivial task. The brain accomplishes it by having these feedback loops check and balance one another. For example, a skillful CEO at a board meeting tries to draw out the disagreement among staff members and to sharpen competing points of view in order to sift through the various arguments and then make a final decision. In the same way, various regions of the brain make diverging assessments of the future, which are given to the dorsolateral prefrontal cortex, the CEO of the brain. These competing assessments are then evaluated and weighed until a balanced final decision is made.

We can now apply the space-time theory of consciousness to give us a definition of most forms of mental illness:

Mental illness is largely caused by the disruption of the delicate checks and balances between competing feedback loops that simulate the future (usually because one region of the brain is overactive or underactive)
.

Because the CEO of the mind (the dorsolateral prefrontal cortex) no longer has a balanced assessment of the facts, due to this disruption in feedback
loops, it begins to make strange conclusions and act in bizarre ways. The advantage of this theory is that it is testable. One has to perform MRI scans of the brain of someone who is mentally ill as it exhibits dysfunctional behavior, evaluating how its feedback loops are performing, and compare it to the MRI scans of normal people. If this theory is correct, the dysfunctional behavior (for example, hearing voices or becoming obsessed) can be traced back to a malfunctioning of the checks and balances between feedback loops. The theory can be disproven if this dysfunctional behavior is totally independent of the interplay between these regions of the brain.

Given this new theory of mental illness, we can now apply it to various forms of mental disorders, summarizing the previous discussion in this new light.

We saw earlier that the obsessive behavior of people suffering from OCD might arise when the checks and balances between several feedback loops are thrown out of balance: one registering something as amiss, another carrying out corrective action, and another one signaling that the matter has been taken care of. The failure of the checks and balances within this loop can cause the brain to be locked into a vicious cycle, so the mind never believes that the problem has been resolved.

The voices heard by schizophrenics might arise when several feedback loops are no longer balancing one another. One feedback loop generates spurious voices in the temporal cortex (i.e., the brain is talking to itself). Auditory and visual hallucinations are often checked by the anterior cingulate cortex, so a normal person can differentiate between real and fictitious voices. But if this region of the brain is not working properly, the brain is flooded with disembodied voices that it believes are real. This can cause schizophrenic behavior.

Similarly, the manic-depressive swings of someone with bipolar disorder might be traced to an imbalance between the left and right hemispheres. The necessary interplay between optimistic and pessimistic assessments is thrown off balance, and the person oscillates wildly between these two diverging moods.

Paranoia may also be viewed in this light. It results from an imbalance between the amygdala (which registers fear and exaggerates threats) and the prefrontal cortex, which evaluates these threats and puts them into perspective.

We should also stress that evolution has given us these feedback loops for a reason: to protect us. They keep us clean, healthy, and socially connected. The problem occurs when the dynamic between opposing feedback loops is disrupted.

This theory can be roughly summarized as follows:

MENTAL ILLNESS

Paranoia

FEEDBACK LOOP #1

Perceiving a threat

FEEDBACK LOOP #2

Discounting threats

BRAIN REGION AFFECTED

Amygdala/prefrontal lobe

MENTAL ILLNESS

Schizophrenia

FEEDBACK LOOP #1

Creating voices

FEEDBACK LOOP #2

Discounting voices

BRAIN REGION AFFECTED

Left temporal lobe/anterior cingulate cortex

MENTAL ILLNESS

Bipolar disorder

FEEDBACK LOOP #1

Optimism

FEEDBACK LOOP #2

Pessimism

BRAIN REGION AFFECTED

Left/right hemisphere

MENTAL ILLNESS