Category: Uncategorized
Infectious Emotions?
Biological systems, such as the circulatory, respiratory, and nervous systems, are groups of organs that function together to perform a common task. Some can also participate in crosstalk with other organ systems. The respiratory system, for example, brings in the oxygen that the circulatory system delivers to all the cells of the body, and maintains blood pH. The endocrine and nervous systems are signaling systems that facilitate communication between different parts of the body by use of hormones and neurotransmitters, respectively. These connections are numerous and complex, but it was previously thought that the immune system and the nervous systems were separate and largely autonomous.
In June 2010, Mauricio Vargas and colleagues from Stanford University School of Medicine reported research in Proceedings of the National Academy of Sciences showing that endogenous antibodies play an important role in repairing peripheral nervous system (PNS) damage. Antibodies are a principal part of the adaptive immune response to infection, but this research suggested that antibodies are also able to clear degenerating myelin which inhibits axon regeneration, akin to a homeostasis function. This repair was only present after PNS injury, whereas myelin debris remained in the central nervous system (CNS) white matter for years. The well known blood-brain barrier concurs with this separation in responses, as it is understood to be impermeable to large proteins such as antibodies.
Various new studies, howeve
r, have shown that behavior, mood, and memory can all be influenced by aspects of the immune system, suggesting that antibodies can somehow infiltrate the brain.
Sammy Maloney was a happy and outgoing 12-year-old boy. In 2002, however, his mother started to notice curious deviations in his personality. In six months, he underwent complete mental deterioration and was diagnosed with obsessive compulsive disorder and Tourette’s syndrome. Shortly afterwards, he was found to be harboring a streptococcal infection, although he exhibited no physical symptoms of one. Interestingly, when he started taking the prescribed antibiotics, his behavior markedly improved.
Madeline Cunningham at the University of Oklahoma has spent several years investigating various behavioral disorders associated with streptococcal infections. Cunningham has shown that antibodies against one group of streptococcal bacteria are able to bind to a site in the brain that controls movement, and consequently trigger the release of dopamine. This could explain the emotional disturbances associated with these types of disorders (1).
Studies also suggest that an activated immune system has other perceivable effects on the nervous system. For example, Jonathan Kipnis of the University of Virginia and his colleagues have shown that learning triggers a stress response in the brain, which causes CD4 cells, a type of T lymphocytes, to gather at the meninges and release interleukin-4. IL-4 switches off the stress response and causes a release of brain-derived neurotrophic factor, which facilitates memory formation. Interestingly, cancer p
atients treated with chemotherapy drugs often experience various cognitive defects and some memory loss. This is commonly called “chemobrain”, and these studies raise the possibility that it is a consequence of immunosuppression. Finally, an immune response against Mycobacterium vaccae has been shown to improve mood by causing neurons in the prefrontal cortex to release excess seratonin.
So it could be that the blood-brain barrier is kind of leaky after all. Understanding the connections between the immune system and the brain could lead to all sorts of ingenious treatments for various disorders. Perhaps those scientists at Stanford will utilize antibodies to develop a treatment for central nervous system repair. Perhaps we’ll one day be faced with immuno-emotive treatments for depression. Who knows? Anything is possible when a long-standing “truth” turns out not to be absolute – I’m optimistic since scientific advancement is often built on the refinement of prior knowledge.
Happiness is Catching – New Scientist
Endogenous Antibodies Promote Rapid Myelin Clearance and Effective Axon Regeneration after Nerve Injury – Proceedings of the National Academy of Sciences
Previous The Nerve Blog post About PNAS Article
Footnote:
(1) Antibodies raised against the Streptococcal M protein and human myocardial tissue, and Guillain-Barre syndrome in response to Campylobacter infection, are well studied examples of cross-reactivity between anti-pathogen antibodies with host tissues.
Smokescreen: Scanning the Addict's Brain
The neuroscience of addiction has been extensively studied, giving priceless insight into what is happening in the addict's brain and what keeps people hooked on drug-seeking behavior. Most of the research, though, has been all about the chemical changes in the brain, delving into the molecular level of receptors, neurotransmitters, and reward pathways, etc. But a new approach is being taken from research focusing on extended applications of neuroscience, such as linking neuroscience and "social research and communication studies." In this video, primary researcher Emily Falk explains the work that is being done at the University of Michigan to try to use the brain as a More
Untangling the Wires
Here's a great video summary from Nature on the recent advances in the field of connectomics by researchers at the Max Planck Institute in Germany and Harvard University:
And the original research, here.
My previous post on Connectomics.
Discussion Preview: Culture-Bound Syndromes with BU Mind and Brain Society
Today, the concept of a 'culture-bound syndrome' seems almost mundane. Surely we already know that particular genes and environmental influences can predispose a population to certain diseases. For example, Ashkenazi Jews are at a much higher risk for developing the genetic defect associated with Tay-Sachs disease than other populations, and one is much more likely to contract malaria in tropical and subtropical regions than in, say, Massachusetts. However, these types of disease have biological causes. What is interesting about the phenomena of culture-bound syndromes is that they have no physical mechanism and arise only from the emerging characteristics of one's culture. More
Middle World
A little self-education goes a long way. Let Richard Dawkins enlighten you (and if you've seen this already, it's never a bad idea to brush up on the basics of life):
Neural Feedback: Smiling
In Justin Bieber’s 2010 smash hit ‘U Smile’ he addresses the idea that when “You smile I smile”, obviously deriving his inspiration from recent work by V.S. Ramachandran on the human mirror neuron system. Over 50 years before Justin Bieber's efforts to bring Ramachandran’s research to the forefront of the media, Dale Carnegie noted in his 1936 masterpiece, How To Win Friends And Influence People, the undeniable positive effects of smiling on the people around you. Carnegie goes on to explain how smiling can actually have a positive affect on the smiler as well. He notes a passage written by the great psychologist William James: More
Moral Code
Why is it wrong to kill babies? Why is it wrong to take advantage of mentally retarded people? To lie with the intention of cheating someone? To steal, especially from poor people? Is it possible that Medieval European society was wrong to burn women suspected of witchcraft? Or did they save mankind from impending doom by doing so? Is it wrong to kick rocks when you’re in a bad mood?
Questions of right and wrong, such as these, have for millenia been answered by religious authorities who refer to the Bible for guidance. While the vast majority of people still turn to Abrahamic religious texts for moral guidance, there are some other options for developing a moral code. Bibles aside, we can use our “natural” sense of what’s right and wrong to guide our actions; a code based on the natural sense would come from empirical studies on what most people consider to be right or wrong. Ignoring the logistics of creating such as code, we should note that the rules in this code would not have any reasoning behind them other than “we should do this because this is what comes naturally.” How does that sound? Pretty stupid.
The other option is to develop a moral code based on some subjective metaphysical ideas, with a heavy backing of empirical facts. “Subjective” means these ideas won’t have an undeniability to them; they are what they are and that’s it. Take as an example the rule such as “we should not kill babies.” There is no objective, scientific reason why we shouldn’t kill babies. Wait!, you say, killing babies is wrong because it harms the proliferation of our species and inflicts pain on the mothers and the babies themselves! But why should we care about the proliferation of our species? About hurting some mother or her baby? While no one will deny that we should care about these, there is nothing scientific that will explain why. Science may give us a neurological reason why we care about species proliferation (it will go something like, “there is a brain region that makes us care about proliferation of our species.”), but why should we be limited to what our brains tend to make us think or do?
Subjective rules like these must therefore be agreed upon with the understanding that they are subject to change. Interestingly, some argue that science can answer moral questions because it can show us what “well-being” is, how we can get it, etc. But the scientific reason why we should care about well-being is nowhere to be found. The result is that we can use science to answer moral questions, but we have to first agree (subjectively) that we want well-being. Science by itself cannot answer moral questions because it shows us what is rather than what ought to be. (Actually, Sam Harris is the only one to argue that science can be an authority on moral issues; his technical faux-pas is an embarrassment to those who advocate “reason” in conduct).
But more on the idea of metaphysically constructed moral codes. What properties should this code have, and how should we go about synthesizing it? Having one fixed/rigid source as an authority for moral guidance is dangerous. Make no mistake: there must be some authority on moral questions, but it must be flexible, and adaptable; it must be able to stand the test of time on the one hand, but to be able to adjust to novel conditions on the other. This sounds a lot like the constitution of the U.S. But even with such a document as The Constitution, which has provided unity and civil progress since the country’s founding, there are some who take its words literally and allow no further interpretation; if it’s not written in the constitution, it can’t be in the law, they argue (see Strict Constructionism versus Judicial Activism). These folks also tend to be rather religious (read: they spend a lot of time listening to stories from the Bible; not to be confused with “spiritual” or of religions other than the Abrahamic ones). So while we must have a moral code, it must be flexible (i.e. change with time) and we must seek a balance between literal and imaginative interpretations, just as we do with the US Constitution.
Why and how is a rigid moral authority dangerous? Our authority must change with time because new developments in our understanding of the world must update how we interact with others. For example, if science finds tomorrow that most animals have a brain part that allows them to feel emotional pain in the same way that humans do, we will have to treat them with more empathy; research on dolphin cognition has recently produced an effort by scientists to have dolphins be considered and treated as nonhuman persons. Furthermore, if we don’t explain why we do certain things, we won’t understand why we do them and therefore won’t know why violating them is bad. This unquestionability aspect of God as moral authority or the Strict Constructionists as law-makers is what makes them particularly dangerous and leads to prejudice and ignorance. Our moral code must therefore be based on empirical research, with every rule being subject to intense scrutiny (think of two-year-olds who keep asking, “but why?”).
But why should we have a moral code in the first place? Perhaps if everyone followed a moral code of some sort, the world would have fewer injustices and atrocities. Getting people to follow a moral code of any kind is a completely different issue.
Nonhuman Personhood for Dolphins
The Science Behind Appetite
“We were hardwired to eat and eat—and particularly to eat fatty foods because we didn’t get them often,” says Sharman Russell, author of Hunger: An Unnatural History. So if you’re among the 200 million Americans who have surpassed their target weight, don’t feel so bad. Somewhere in your brain, there is a circuit for food.
While eating is vital to life, it’s a voluntary action. But nature has made eating irresistible. So what is the science behind this irresistibility? Over the course of a year, the average adult male consumes about 900,000 calories, yet his weight doesn’t fluctuate by more than a pound. It takes a lot of effort from your internal systems to keep this balance, and an important substance behind this is a hormone called ghrelin.
Ghrelin, identified in 1999, is produced in the gut in response to meal schedules. Its purpose is to give the empty feeling we know as the need to eat. When ghrelin hits the brain, it affects three specific areas: the hindbrain, the hypothalamus, and the mesolimbic reward center. The hindbrain controls the body’s automatic and unconscious processes. It is responsible for the sensation of hunger. For the purposes of eating and digesting, the hypothalamus governs the rates of metabolism. And at the center of the midbrain lies the mesolimbic reward center, where the feelings of pleasure and satisfaction are processed. This is what motivates us to eat and keep eating.
Of course, other substances in our body govern our appetite as well as ghrelin. Even as ghrelin continues to arouse our appetite, other systems are standing by to slow down the process. The most basic such step occurs in the stomach and intestines. Distension sends a signal to the brain to stop eating. That message is then reinforced by a peptide called cholecystokinin (CCK) and two hormones called PYY and GLP-1. They all send complex chemical messages that literally tell the brain to stop eating. And, in the case that food consumption continues, the body has a last resort appetite-supressing hormone called leptin. Discovered in 1994, leptin affects the hypothalamus where it inhibits a pair of neuropeptides known to stimulate appetite.
So with all these measures in place to stop the body from eating, why do we overeat? Studies have shown that ghrelin hits the mesolimbic reward region very powerfully. It has been shown that this part of obese people’s brains activate very similarly to how the brains of drug addicts activate when exposed to their preferred substance. While the causes of over eating are very obvious, the real question is: how can we control it? Diet and exercise are often the recommendations (and should be followed), but the minds who discovered leptin, ghrelin, and all the other appetite-related peptides and hormones are also looking for ways to harness the power so we can take better control of it on our own.
Hunger: An Unnatural History - Sharman Russell
Beefing Up Your Brain
"Dude, my action potentials are on fire right now."
- Are you aging and senile?
- Do you find yourself frequently forgetting facts and misplacing objects?
- Are you simply dissatisfied with your cognitive strength?
The Posit Science Brain Fitness Program might be right for you!
As we age, our brains age with us, slowly deteriorating over time. For the fast-paced lives we now lead however, having mediocre cognitive abilities just doesn’t cut it. Famed neuroscientist, brain-plasticity connoisseur, and new businessman Michael Merzenich has engineered a series of “brain fitness” activities that are claimed to help individuals keep their minds in tip-top shape.
Merzenich’s Posit Science program is based on neuroplasticity, the ability of the brain to reorganize itself. While cortical reorganization is a remarkable asset of the brain to adapt to change, it may also be detrimental when the brain is not utilized to its full potential. Dr. Merzenich asserts that in order to maintain neurological skill throughout adulthood, individuals must continue to train the various cognitive-sensory facets of the mind.
The clinically supported Posit Science program offers a multi-modal, total brain training package composed of both an auditory skill and a visual skill program. This training includes a series of six computer-based programs specifically designed to improve the brain’s auditory-visual processing and perceptive abilities.
Currently, Posit Science is looking to broaden the applicability of its products by venturing into the world of social networking. The company has recently developed and launched a networking site called “Brain Odyssey,” through which individuals can work together to solve mysteries and virtually explore cities throughout the world, all while collaborating on cognitive training tasks.
But Wait...!
In addition to offering a mental fitness program, the company website also features several brain games as well as a few “brain tests” as an informal way of testing one’s cognitive prowess, free of charge.
Click here to get your cognitive fitness on today!
A "better brains" collective launches to improve cognition of the masses - Scientific American
