The following question was posted after my last blog. “In your book DEAD HEAD, I was fascinated by how you laid out the challenges the surgeon, Russell Lawton, faced in keeping the injured man's severed head alive and functioning. You made it seem totally plausible, even down to devising a way for the head to communicate with his fellow terrorists. Ethical issues aside, could you ever see a time where a brain could be transferred to a host body, or perhaps just the thoughts and memories, not the actual brain?”
Transplanting a brain is terrific fodder for science fiction, but it impossible at the present time. Why? Huge reasons. Let’s say Fictitious Person X has some illness that is destroying his body but leaving his brain perfectly intact and functioning at intellectual levels similar to Stephen Hawkings. So the decision is made to transplant X’s brain into a human body of a brain Dead Person Y. (Most likely, this would be a person shot through the head. Why? Because chances are they would be young, without other disease, so a healthy body.)
To actually remove the brain would be impossible. Why? Well, you would have to cut all the nerves that connect X’s brain to the eyes, nose, face, mouth, etc. Then you’d have to sever the spinal cord and blood vessels to and from the brain. You might be able to hook the blood vessels to Y’s body but then you’d be out of luck. There is no way you can reconnect all those nerves or the spinal cord. So you’re left with a living brain without any sensory input.
As described in DEAD HEAD, experiments were carried out years ago in transplanting heads from one animal to another. (For reasons I’ve never understood). These experiments failed because of tissue rejection issues that transplantation medicine has subsequently solved. But even if total head transplants could be done now, the result would be a person who was quadriplegic (because you would still not be able to hook up a functioning spinal cord).
Okay, so maybe total brain transplants are not feasible, but how about memory? Good question. And the issue of what is memory and where it is stored will be a future topic. Suffice it to say that memories considered to be “long term” (events that happened days ago) are probably stored in the brain cells chemically, perhaps even as proteins. So, theoretically it may be possible to eventually transfer memories from one person to another. But this is not something likely to happen in the near future.
The second part of the question is: “Ethical issues aside, could you ever see a time where a brain could be transferred to a host body, or perhaps just the thoughts and memories, not the actual brain?”
Here the discussion quickly changes from science to philosophy. First, defining (in physiologic terms) what a “thought” is, is in itself problematic. There is not “thought center. There are various brain regions that are essential for regulating wakefulness and sleep. If some of these areas are damaged, for example during head injury or stroke, the person may become non-responsive and stay in a coma. But do they have thoughts? Some may, others probably do not. We do, however, think during sleep. I’m sure all of us have had the phenomenon of awakening in the morning having solved a problem during sleep. But what brain areas are responsible for logic? That is something we don’t know for certain.
Thursday, January 28, 2010
Friday, January 22, 2010
1/22/2010
I was asked to explain some of the tests we use to evaluate the brain. This isn’t a topic easily covered in one installment, so it’ll be in segments.
The first attempt to look at the brain in a living human was the X-ray. But a standard front-to-back, side-to-side X-rays don’t give a picture of the brain at all. They show only the bones of the skull and the holes nerves pass through on their way to other structures (for example, the nerves that connect the eyes to the brain). It was the advent of small computers that advanced brain imaging.
For years before computers radiologists used the technique of tomograms for more detail than routine X-rays. A tomogram is a “slice” of a larger image. Imagine cutting a snapshot into slices. Arrange all those slices in order and you have a complete picture. Well, you can make slices of the head with X-rays too. Move an X-ray beam in an arc and there is one small point (focal point) through which all the beams pass. The further from that point, the more spread out (or out of focus) the beams are. Radiologists learned that this concept could be used to make very thin and focused X-ray “slices” of the brain. By moving an X-ray beam in an arc over the head the focal point will be in focus but the surrounding areas will be blurred. If you repeat this process at step-wise distances through the head, you would end up with “slices,” or images that are focued at varying distances through the skull. Tomograms of the skull were a huge advantage over regular skull films when looking for small changes in the bones caused by tumors.
Fast, reasonable sized, computers made it possible for these tomograms to be merged together to come up with 3D images. They also allowed X-ray to be taken and then displayed electronically without the use of film. As the speed of computers increased so did the number of slices that could be made in a reasonable period of time. More slices per picture resulted in improved detail. And as detail improved, so did the ability to show differences in brain matter instead of just bone detail. Because computers were used to merge tomograms, the technique is called computerized tomography, or CT scan. (Originally, the term computerized axial tomography, or CAT scan was used). Basically, CT scans are very sophisticated skull X-rays.
Magnetic Resonance Scans (MRI) make tomographic brain pictures from magnetic energy instead of X-rays. Remember the cartoon picture of an atom with electrons orbiting a nucleus. Because each electron is a negative charge, they try to stay away from each other like north poles of two magnets. If you place an atom in a very strong magnetic field the electrons are forced to align their orbits more than normally occurs. But the moment the magnetic field stops, the electrons fly back to their original orbits and in doing so, send off a small radio signal. Very sensitive radio receivers can pick up these signals. Because atoms from different elements (say, carbon and oxygen) have different numbers of electrons, the radio signals for different compounds are characteristic. Just like different radio stations transmit on their own frequency. Water has a different signal than protein or fat. These differences allow the MRI to give us very detailed pictures of the brain and allow us to see changes, such as tumors.
Although CT and MRI scans give detailed pictures of brain structure they tell us nothing about brain function. In contrast, PET Scans (positron emission tomography) provide us with information about brain activity, but without good structural detail of an MRI. PET scans are produced by injecting a chemical into the body called a radionucleotides, which are substances that emits activity that can be detected by Geiger-counter like sensors. Chemicals, such as glucose, can be made to emit positrons.
If a person does a task, for example move their right index finger, the brain region controlling that task works harder than other brain areas that remain idle, and the nerve cells producing the task require more glucose and oxygen. This change in glucose metabolism is what PET scans detect.
SPECT scans (single-photon emission computed tomography) are similar to PET scans but use less expensive equipment and a different technique. SPECT scans are primarily used to show blood flow through the brain and can be used, for example, to detect small strokes.
In summary, PET and SPECT scans give us information about blood flow and metabolism whereas CT and MRI show us brain structure. With very sophisticated computers, the pictures obtained from these different studies can be combined. For example, the information from an MRI and PET scan can be combined and the information used to help diagnose various brain problems.
The first attempt to look at the brain in a living human was the X-ray. But a standard front-to-back, side-to-side X-rays don’t give a picture of the brain at all. They show only the bones of the skull and the holes nerves pass through on their way to other structures (for example, the nerves that connect the eyes to the brain). It was the advent of small computers that advanced brain imaging.
For years before computers radiologists used the technique of tomograms for more detail than routine X-rays. A tomogram is a “slice” of a larger image. Imagine cutting a snapshot into slices. Arrange all those slices in order and you have a complete picture. Well, you can make slices of the head with X-rays too. Move an X-ray beam in an arc and there is one small point (focal point) through which all the beams pass. The further from that point, the more spread out (or out of focus) the beams are. Radiologists learned that this concept could be used to make very thin and focused X-ray “slices” of the brain. By moving an X-ray beam in an arc over the head the focal point will be in focus but the surrounding areas will be blurred. If you repeat this process at step-wise distances through the head, you would end up with “slices,” or images that are focued at varying distances through the skull. Tomograms of the skull were a huge advantage over regular skull films when looking for small changes in the bones caused by tumors.
Fast, reasonable sized, computers made it possible for these tomograms to be merged together to come up with 3D images. They also allowed X-ray to be taken and then displayed electronically without the use of film. As the speed of computers increased so did the number of slices that could be made in a reasonable period of time. More slices per picture resulted in improved detail. And as detail improved, so did the ability to show differences in brain matter instead of just bone detail. Because computers were used to merge tomograms, the technique is called computerized tomography, or CT scan. (Originally, the term computerized axial tomography, or CAT scan was used). Basically, CT scans are very sophisticated skull X-rays.
Magnetic Resonance Scans (MRI) make tomographic brain pictures from magnetic energy instead of X-rays. Remember the cartoon picture of an atom with electrons orbiting a nucleus. Because each electron is a negative charge, they try to stay away from each other like north poles of two magnets. If you place an atom in a very strong magnetic field the electrons are forced to align their orbits more than normally occurs. But the moment the magnetic field stops, the electrons fly back to their original orbits and in doing so, send off a small radio signal. Very sensitive radio receivers can pick up these signals. Because atoms from different elements (say, carbon and oxygen) have different numbers of electrons, the radio signals for different compounds are characteristic. Just like different radio stations transmit on their own frequency. Water has a different signal than protein or fat. These differences allow the MRI to give us very detailed pictures of the brain and allow us to see changes, such as tumors.
Although CT and MRI scans give detailed pictures of brain structure they tell us nothing about brain function. In contrast, PET Scans (positron emission tomography) provide us with information about brain activity, but without good structural detail of an MRI. PET scans are produced by injecting a chemical into the body called a radionucleotides, which are substances that emits activity that can be detected by Geiger-counter like sensors. Chemicals, such as glucose, can be made to emit positrons.
If a person does a task, for example move their right index finger, the brain region controlling that task works harder than other brain areas that remain idle, and the nerve cells producing the task require more glucose and oxygen. This change in glucose metabolism is what PET scans detect.
SPECT scans (single-photon emission computed tomography) are similar to PET scans but use less expensive equipment and a different technique. SPECT scans are primarily used to show blood flow through the brain and can be used, for example, to detect small strokes.
In summary, PET and SPECT scans give us information about blood flow and metabolism whereas CT and MRI show us brain structure. With very sophisticated computers, the pictures obtained from these different studies can be combined. For example, the information from an MRI and PET scan can be combined and the information used to help diagnose various brain problems.
Wednesday, January 20, 2010
1/20/2010
On the Brian Williams 6:00 pm news last night was a segment on the deployment of medical services in Haiti by various relief organizations. Special emphasis was given to how quickly and effectively the Israeli military was able to set up a fully functional field hospital on the island. Unlike some of the first responders, the Israelis are equipped to photograph patients’ faces as the first step to starting an electronic medical record (EMR) on each victim. Very smart. Very efficient. This is how it should be done.
My first thriller, Deadly Errors, deals with the multiple advantages of EMRs over the traditional pen and paper charts most of us are used to seeing. In April 2004, President Bush issued executive order 13335, which established a new executive position charged with developing a strategic plan and incentives for adopting EMRs. In March of this year President Obama convened a health-care summit in Washington to identify programs that would improve quality and stop the growth of burgeoning costs. He stated that his policies would be based on rigorous scientific evidence of benefit. His leading proposal was the national adoption of electronic medical records -- a computer-based system that would contain every patient's clinical history, laboratory results, and treatments. In spite of all the press on the benefits of EMRs, it appears the transition from paper to printed circuits continues to be slower than it should be. One factor is the cost of this overhaul. It is expensive, and any real economic gain from doing it will be slow and difficult to measure. Yet the segment on NBC news showed some very clear benefits in a very specific situation.
My first thriller, Deadly Errors, deals with the multiple advantages of EMRs over the traditional pen and paper charts most of us are used to seeing. In April 2004, President Bush issued executive order 13335, which established a new executive position charged with developing a strategic plan and incentives for adopting EMRs. In March of this year President Obama convened a health-care summit in Washington to identify programs that would improve quality and stop the growth of burgeoning costs. He stated that his policies would be based on rigorous scientific evidence of benefit. His leading proposal was the national adoption of electronic medical records -- a computer-based system that would contain every patient's clinical history, laboratory results, and treatments. In spite of all the press on the benefits of EMRs, it appears the transition from paper to printed circuits continues to be slower than it should be. One factor is the cost of this overhaul. It is expensive, and any real economic gain from doing it will be slow and difficult to measure. Yet the segment on NBC news showed some very clear benefits in a very specific situation.
Sunday, January 17, 2010
January 17, 2010
The first questions sent to me was how often will I update this blog. Well, probably every week or so.
Two readers asked how the brain adapts to the loss of a limb or organ and/or how this change is perceived by the afflicted person. It’s an interesting question, one that has been the focus of much research. About 95% of amputees experience sensations in areas where the missing limb used to be. So if you lost, say your left leg, you might feel your left foot itching. This is called Phantom Limb Phenomenon. The perceived sensations vary from person to person ranging from vague feelings of warmth to shooting pain. The phenomenon may occur fairly soon after losing the limb and continue on through the person’s life. Interestingly, a researcher at McGill University, Ronald Melzack, discovered that phantom limb may occur in children born without legs.
Okay, so what causes these a person to feel these sensations in a body part that is no longer there?
Well, the neurologic basis for this isn’t known for certain and scientists debate whether it’s due to changes at the level of the spinal cord or higher in the nervous system - perhaps even on the surface of the brain, the cortex. (My money is on areas higher up than the spinal cord). Regardless, it’s likely due to changes in nerve cell behavior that result from the loss of connections. If you lose a leg, you lose the nerves that transmit sensations (such as pain, vibration, touch) from your muscles and skin to the spinal cord on up to the cortex. It is the processing of this information within the cortex that actually “makes sense” out of it.
Each side of the brain has an organized map of sensation (called the homunculus) from the opposite side of the body. This map is laid down as the brain develops and is organized in pretty much the same way from person to person. It doesn’t change much during one’s life. So the leg area of the homunculus receives information from the nerves to the leg via the spinal cord and brain stem. If the nerves to the leg are cut off, as happens in an amputation, the nerves cells (neurons) in the cortex no longer receive any information from the leg.
Nerve cells communicate with each other through connections called synapses. If a neuron loses synapses it becomes hyperactive and may begin to produce signals to other neurons spontaneously. (Like the kid in school who threw spitballs when the teacher wasn’t looking.) This spontaneous activity from the brain areas that gave us conscious appreciation of the amputated body area is why phantom limb phenomenon happens. Because the brain area that used to make sense of the lost body part becomes spontaneously active, we perceive sensations for the missing part.
Two readers asked how the brain adapts to the loss of a limb or organ and/or how this change is perceived by the afflicted person. It’s an interesting question, one that has been the focus of much research. About 95% of amputees experience sensations in areas where the missing limb used to be. So if you lost, say your left leg, you might feel your left foot itching. This is called Phantom Limb Phenomenon. The perceived sensations vary from person to person ranging from vague feelings of warmth to shooting pain. The phenomenon may occur fairly soon after losing the limb and continue on through the person’s life. Interestingly, a researcher at McGill University, Ronald Melzack, discovered that phantom limb may occur in children born without legs.
Okay, so what causes these a person to feel these sensations in a body part that is no longer there?
Well, the neurologic basis for this isn’t known for certain and scientists debate whether it’s due to changes at the level of the spinal cord or higher in the nervous system - perhaps even on the surface of the brain, the cortex. (My money is on areas higher up than the spinal cord). Regardless, it’s likely due to changes in nerve cell behavior that result from the loss of connections. If you lose a leg, you lose the nerves that transmit sensations (such as pain, vibration, touch) from your muscles and skin to the spinal cord on up to the cortex. It is the processing of this information within the cortex that actually “makes sense” out of it.
Each side of the brain has an organized map of sensation (called the homunculus) from the opposite side of the body. This map is laid down as the brain develops and is organized in pretty much the same way from person to person. It doesn’t change much during one’s life. So the leg area of the homunculus receives information from the nerves to the leg via the spinal cord and brain stem. If the nerves to the leg are cut off, as happens in an amputation, the nerves cells (neurons) in the cortex no longer receive any information from the leg.
Nerve cells communicate with each other through connections called synapses. If a neuron loses synapses it becomes hyperactive and may begin to produce signals to other neurons spontaneously. (Like the kid in school who threw spitballs when the teacher wasn’t looking.) This spontaneous activity from the brain areas that gave us conscious appreciation of the amputated body area is why phantom limb phenomenon happens. Because the brain area that used to make sense of the lost body part becomes spontaneously active, we perceive sensations for the missing part.
Wednesday, January 13, 2010
January 13, 2010
If you’re looking for someone to blame, Vicki Hinze is your culprit. She talked me into starting this. So here goes. What will I be ruminating about, you ask? Well, a wide range of topics from issues I raised in my books DEADLY ERRORS and DEAD HEAD, to my views on stories in the popular press that deal with brain function. Most people are intrigued with how the brain works. I know I am. It was the most compelling reason I chose to specialize in neurosurgery.
First a bit of background for readers who don’t know me. I started out in “academic” neurosurgery with the goal of becoming a beloved gray haired professor renown for his idiosyncrasies. To me, research was a natural extension of my childhood curiosity that caused me to dismantle my toys within hours of getting my hands on them.
Throughout medical school I worked on a psychiatrist’s research team. Thomas Holmes was his name and he was fascinated by the relationship between the life stress and of illness. We all intuitively realize this phenomenon because we’ve seen the obvious: a colleague who ends up in the Coronary Care Unit of the local medical center after completing a very difficult project. The day after we solemnly gather around the coffee maker and say, “It’s no wonder he got sick, just look at the hours he put it.” Interestingly, stress-induced illness usually occurs after, rather than during stress.
The field of medicine that studies with the effect of life change on illness onset is termed psychosomatic medicine. (Many people erroneously interpret the term psychosomatic as something entirely different.) However, in the example above other life events may have contributed more to producing the heart attack than just hard work and long hours in at his desk. The death of a pet, a daughter leaving for school, a balloon payment due. In fact, Holmes and Rahe developed a scale that rated the relative seriousness of numerous life events (http://en.wikipedia.org/wiki/Holmes_and_Rahe_stress_scale).
What interested Holmes greatly was the ways in which different personalities channel the deleterious effects of stress. By this, I mean that given the same amount of stress, why does one person end up ulcers and another person have a heart attack? Well, it has to do with how our individual bodies adapt and deal with change. And that is a effected by our psychological make up.
The idea that change, good or bad, is a stress to our bodies not new. Holmes was influenced by work started in the 40s. This concept has also been generalized from the individual to groups. In 1970 sociologist and futurist Alvin Tofler wrote, FUTURE SHOCK, (http://en.wikipedia.org/wiki/Future_Shock)
a bestseller that dealt with the effects of change on society. Toffler's shortest definition of future shock is a personal perception of "too much change in too short a period of time."
So what does this have to do with any of my novels? Well, DEAD HEAD is a story about a head kept alive without an attached body. When writing this story I often wondered what would happen to a person’s mind if the body were physically detached. I don’t know the answer. What about people who survive neck injuries as quadriplegics? Although they may not have use of their limbs, most of them still have nerves that supply information to the brain, such as the Vagus nerve, from various internal organs. And it is sensations from these nerves that help give our emotions “depth.” The study of psychosomatic medicine teaches us that the mind has huge effects on our body, but sometimes we forget that the body also huge effects on our minds.
I encourage readers to email me with questions about the brain that could result in some short, interesting posts.
First a bit of background for readers who don’t know me. I started out in “academic” neurosurgery with the goal of becoming a beloved gray haired professor renown for his idiosyncrasies. To me, research was a natural extension of my childhood curiosity that caused me to dismantle my toys within hours of getting my hands on them.
Throughout medical school I worked on a psychiatrist’s research team. Thomas Holmes was his name and he was fascinated by the relationship between the life stress and of illness. We all intuitively realize this phenomenon because we’ve seen the obvious: a colleague who ends up in the Coronary Care Unit of the local medical center after completing a very difficult project. The day after we solemnly gather around the coffee maker and say, “It’s no wonder he got sick, just look at the hours he put it.” Interestingly, stress-induced illness usually occurs after, rather than during stress.
The field of medicine that studies with the effect of life change on illness onset is termed psychosomatic medicine. (Many people erroneously interpret the term psychosomatic as something entirely different.) However, in the example above other life events may have contributed more to producing the heart attack than just hard work and long hours in at his desk. The death of a pet, a daughter leaving for school, a balloon payment due. In fact, Holmes and Rahe developed a scale that rated the relative seriousness of numerous life events (http://en.wikipedia.org/wiki/Holmes_and_Rahe_stress_scale).
What interested Holmes greatly was the ways in which different personalities channel the deleterious effects of stress. By this, I mean that given the same amount of stress, why does one person end up ulcers and another person have a heart attack? Well, it has to do with how our individual bodies adapt and deal with change. And that is a effected by our psychological make up.
The idea that change, good or bad, is a stress to our bodies not new. Holmes was influenced by work started in the 40s. This concept has also been generalized from the individual to groups. In 1970 sociologist and futurist Alvin Tofler wrote, FUTURE SHOCK, (http://en.wikipedia.org/wiki/Future_Shock)
a bestseller that dealt with the effects of change on society. Toffler's shortest definition of future shock is a personal perception of "too much change in too short a period of time."
So what does this have to do with any of my novels? Well, DEAD HEAD is a story about a head kept alive without an attached body. When writing this story I often wondered what would happen to a person’s mind if the body were physically detached. I don’t know the answer. What about people who survive neck injuries as quadriplegics? Although they may not have use of their limbs, most of them still have nerves that supply information to the brain, such as the Vagus nerve, from various internal organs. And it is sensations from these nerves that help give our emotions “depth.” The study of psychosomatic medicine teaches us that the mind has huge effects on our body, but sometimes we forget that the body also huge effects on our minds.
I encourage readers to email me with questions about the brain that could result in some short, interesting posts.
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