Thursday, July 5, 2007

What is Consciousness?

...consciousness is by nature multifaceted. Clearly, attention is needed, as attention is the arbiter of awareness, the gatekeeper to the senses. Perception must then arise from attention; perception is a key to the kingdom of the mind. Though attention and perception enable us to be sensitive to our environment, they don’t enable us to be conscious of it, unless we also have a template to which new perceptions can be compared. Thus, memory is an integral part of consciousness. The final and most ineffable element of consciousness is awareness; this can be understood as one part of the brain monitoring another part, watching it work. Thus, we propose that consciousness arises only when a subject shows a combination of attention, perception, memory, and awareness.

But what is the function of consciousness? Is consciousness even necessary? Would we be recognizably human without it? Is consciousness a precondition for the adaptations that set us apart from other organisms? Is language or social adaptation even possible without consciousness? Or is consciousness needed only if language and sociality evolve to the level of sophistication seen in humans? Could we make do and be human with less consciousness? Or is consciousness the minimal qualification for the human condition? In our struggle to understand consciousness, we must confront the possibility that the brain may be unable to understand the mind and that we may always be a bit mystified by our own abilities and capacities.

From "The Evolving Brain," Chapter 9

The Placebo Effect and the Brain

The placebo effect is the tendency for people to respond actively to an inactive medication, to gain a benefit from treatment merely because they expect the treatment to work. In essence, the placebo effect is a state of willed wellness and active anticipation. There is a compelling link between pain and placebo, as it is widely known that “sugar pills” can reduce the perception of pain. One study of placebo for post-operative pain found that placebo was 56% as effective as morphine, even though morphine is considered to be a highly potent analgesic. This simple observation makes it clear that placebo cannot be defined as an “inactive” medication: if dulling pain is the desired result, then pain-killing placebo is active.

Is it possible that placebo is simply the medical name that we give to hope? This concept would explain a great deal about the placebo effect. Any patient who undertakes therapy in a state of hopeful expectancy is apparently primed to show a placebo effect. An expectation of benefit from medical treatment is much like an expectation of reward from any other behavior, and the placebo effect seems to engage the “reward circuitry” of the brain. This circuitry probably evolved to motivate survival-enhancing behaviors like eating or mating. The placebo effect thus appears to be hardwired in the human brain, as it depends upon primordial and quite powerful brain circuitry crucial to our survival.

It would be incorrect to dismiss the placebo effect as being “all in your head,” as if that made it somehow less than real. The placebo effect is not imaginary; the physiological events that are induced by a placebo are often similar to the physiological events that are caused by the drug that the placebo replaces. Placebo given instead of morphine can cause respiratory depression, just like real morphine; placebo given instead of L-dopa can moderate tremor in Parkinsonian patients, just like real L-dopa; placebo given instead of cyclophosphamide can cause suppression of the immune system, just like real chemotherapy; and placebo given instead of analgesia can reduce heart rate in a person experiencing pain, just like a real painkiller.

Embryonic Stem Cells and Brain Disease





A Personal View of Evolution

I am both a believing Christian and a practicing scientist. I believe that the Bible provides insight into the most difficult questions that face humanity, that it treads fearlessly where science will forever be reticent, that it is a product of thousands of years of thinking by some of the best minds in theology. Yet I am also a biologist and an advocate of evolution. I think that evolution has extraordinary power to explain seemingly-unrelated observations, that it may be the finest and strongest and best example of what science strives to be, that it is the product of more than a century of thinking by some of the best minds in science.

Evolution is a gradual process of change; to a biologist this change relies on simple precepts:

1) Variation exists. Any large gathering of people will include some who are old and some who are young, some who are weak and some who are strong. It could be argued that most such variation is meaningless in an evolutionary sense, and this may well be true. But variation exists in all organisms of all species in all places.

2) Some variants are more successful than others. Imagine a herd of antelope, in which some are old and some are young, some are weak and some are strong. Clearly, if a lion were stalking that herd, the old or the weak would be more likely to suffer predation. Predation is not random; lions risk injury every time they hunt, so they seek the weakest prey. Even then, lions are not always successful; sometimes they are unable to kill their prey. Nevertheless, there is a stronger selection pressure against the weak than against the strong.

3) Variation is heritable. Everything we know about our own families convinces us that certain traits are likely to run in families; tall parents tend to have tall children, just as near-sighted parents tend to have near-sighted children. Everything we know about genetics concurs that certain traits are passed down to offspring, often with a high degree of fidelity.

4) Successful variants tend to become more abundant over time. Because certain individuals are more likely to survive long enough to reproduce, and because those individuals are able to pass specific traits on to their offspring, those traits are well-represented in future generations. In contrast, other individuals may have traits that lead to premature death, so these traits are less likely to be passed along. Over time, successful traits will tend to increase in a population, whereas unsuccessful traits will gradually be lost.

The “inventiveness” of evolution emerges from a combination of processes that would seem to be polar opposites; a random process of change or mutation, and a non-random process of assessing that change, in the harshest possible fashion. Though mutation is indeed a random process, mutations are subject to natural selection, which is far from a random process.

Mutation generates few changes that are ultimately successful, just as a blind watchmaker would rarely be able to alter a watch to make it more accurate. We would not accept repairs by a blind watchmaker without testing whether the watch still works. Similarly, random changes to an antelope are subjected to the stringent selection pressure of a hungry lion. Thus, the process of natural selection removes unsuccessful mutations from the gene pool in the most unforgiving way imaginable. The lame, the halt, the weak, and the poorly-adapted; all are killed with an egalitarianism that is inexorable. Evolution is not a random process at all.

Among scientists, the details of evolution are subject to argument, but it is not controversial in any larger sense. It is essentially impossible to be a biologist without accepting the tenets of evolution, just as it is impossible to be an astronomer without accepting gravity. It is not that evolution is a belief system; evolution is an incredibly elegant, simple, powerful, direct, testable, and compelling set of ideas. Evolution is a “theory” in the same sense that gravitation is a “theory”; there are aspects of gravitation that are still not well understood, but we won’t fly off into space while we argue the details.

Understanding the Brain / Knowing the Mind

Can the brain ever truly understand itself? Is there a distinction between understanding the brain and knowing the mind? Are those traits that we perceive to be uniquely human, traits such as creativity or altruism or spirituality, dependent upon attributes unique to the human brain? Is it consciousness that makes us fully human, or do we share consciousness with many other creatures? How is it possible that the human brain, probably the most complex and sophisticated object in the universe, could have arisen in a world so often characterized by chaos? Has the human brain changed over time and will it continue to change? Did the brain evolve or was it necessarily created in its final form? Are the mechanisms of mutation and natural selection adequate to explain the human brain, or do they fall woefully short? How can we explain what we are?

From "The Evolving Brain," Preface

The Anthill of the Brain

A brain is like an anthill. Tiny neurons are the ants, performing their circumscribed tasks in a manner determined by the role they were born to serve. They look no farther than their nearest neighbors, they understand nothing of the larger structure that results from their persistent action. Although there are an enormous variety of tasks to perform, each neuron, like each ant, can do a limited number of tasks, each in a limited way. And yet complexity emerges, in an anthill as in a brain, in ways that cannot be predicted.

From "The Evolving Brain," Chaper 1

The "Intelligent Design" Fallacy

If we entered a deserted Rome, knowing nothing whatsoever of its history, what would we make of it? Would we see St. Peter’s Basilica and conclude that it is so beautiful that only God could have built it? As naïve as this seems, this is exactly what believers in intelligent design do when they argue that evolution cannot have built the human brain.

From "The Evolving Brain," Afterword