Archive for the 'CNS Diseases and Disorders' category

Bulimia and the Vaso-Vagal Reflex

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This is another post in Sci's investigation into the current studies being performed on eating disorders, particularly binge eating and bulimia. Usually I try to focus on the dysregulation of reward-related systems in these disorders, but this paper will be a little different. Faris et al. "De-Stabilization of the Positive Vago-Vagal Reflex in Bulimia Nervosa" Physiology and Behavior, 2008.
It's kind of in the nature of an eating disorder that there aren't any really funny pictures or something that Sci can put in here.
So before we go forward, here's a kitten.

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A Follow up: Depression, p21, CREB, and more

Everyone once in a while, someone sends Sci email. Often it's silly. This one, however, was very good in that it asked for some clarification on a series of posts that I've been working on looking at clinical depression and possible causes and treatments, including neurogenesis in the hippocampus, cell cycle controls, and CREB.
And luckily, the guy who sent it gave Sci permission to repost, which is good, because it allows me to clarify some stuff. Here goes:

Hi Sci: I read your blog about how antidepressants stimulate neurogenesis in the hippocampus. Since the CREB deficient mice had robust neurogenesis and normal serotonin I wasn't sure why they were anxious. Apparently they did benefit from antidepressants right away on the tail suspension and forced swim tests so the neurogenesis hypothesis took a bit of a whack. To add to the complexities I just read about MIF (macrophage migration inhibitory factor). Apparently reducing the amount of MIF in the rat hippocampus dramatically reduces neurogenesis and increases anxiety. Do you understand how CREB and MIF are related? I'm trying to get a handle on this whole complex area. Thanks.

All right, I'm going to try this before my first cup of coffee and we'll see how it goes:

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The Neurogenesis theory of depression and a little guy called CREB

Sci wishes she could begin this post with something clever. But she has a cold. Suffice it to say that this paper is cool and interesting. And also, as Sci has a cold, I expect all of you to read this post out loud to yourselves in suitably stuffy, gluey Sci-voices.

(*sniff*) Gur et al. "cAMP Response Element-Binding Protein Deficiency Allows for Increased Neurogenesis and a Rapid Onset of Antidepressant Response" The Journal of Neuroscience, 2007.
(Yeah, yeah, the title is long and scary. Worry not, Sci will 'splain.)
And this paper is especially good because it allows Sci to write a post on a topic she's been meaning to get to even since she did a depression series way back when: the neurogenesis theory of antidepressant responses.
So here we go. And a new neuron is born.

(From Bumpy Brains. Sci thinks the rendition of diapers as glia is hilarious.)

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7 responses so far

SFN Neuroblogging: Got Type 2 Diabetes on the Brain

Oct 26 2009 Published by under Academia, CNS Diseases and Disorders, Neuroscience

As some of my readers from WAY back (all two of you, hi guys!) may know, diabetes is one of Sci's favorite things. It's one of those things that, if she could start her entire little sciency life over, would be something she would heavily consider as a focus. Heck, there's always another post-doc, right?
Anyway, you might think that diabetes would not be one of the things generally discussed at Society for Neuroscience meetings. But you would be wrong. The symptoms of diabetes, type I or II, stem from not enough insulin, whether that is because you don't produce any (type I) or you don't have enough and aren't sensitive enough to what you have (type II). Insulin isn't just limited to the gut, pancreas, and muscles, however. It's also important in the brain. Normally, your brain is pretty responsive to blood levels of glucose, no matter what, because you want your brain to be the last thing to go when your blood sugar levels drop. But insulin still plays an important role, and insensitivity to insulin, like that seen with type II diabetes extends to the brain as well.
This study taught Sci a lot of things that she didn't necessarily know. First, it taught her that insulin sensitivity is affected by free fatty acid levels. And it taught her that both of these together could have major effects on cognitive impairment. Suddenly the major increases in type II diabetes are looking a little more scary.
V. E. COTERO, E. C. MCNAY "Effect of intrahippocampal FAs with varied saturations on spatial memory in adult Sprague-Dawley rats"
Doesn't sound like anything to do with type II diabetes, does it? You would be surprised. 🙂

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Best. Modelling Paper. Ever.

Aug 17 2009 Published by under CNS Diseases and Disorders

The abstract says it all:

Zombies are a popular figure in pop culture/entertainment and they are usually portrayed as being brought about through an outbreak or epidemic. Consequently, we model a zombie attack, using biological assumptions based on popular zombie movies. We introduce a basic model for zombie infection, determine equilibria and their stability, and illustrate the outcome with numerical solutions. We then refine the model to introduce a latent period of zombification, whereby humans are infected, but not infectious, before becoming undead. We then modify the model to include the effects of possible quarantine or a cure. Finally, we examine the impact of regular, impulsive reductions in the number of zombies and derive conditions under which eradication can occur. We show that only quick, aggressive attacks can stave off the doomsday scenario: the collapse of society as zombies overtake us all.

They use the mathematical models applied to outbreaks of infectious diseases to show that -- absent a cure or concerted eradication of large proportions of zombies simultaneously -- we are well and truly screwed. This realization should in no way detract from the observation that MATH IS COOL. It will be a damn shame when the zombies eat it out of our brains.
Hat-tip: Marginal Revolution

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Key paper in depression genetics disputed

Jun 24 2009 Published by under CNS Diseases and Disorders

I wanted to draw attention to a new paper in JAMA recently because it reveals a lot about how conditional most of the statements we make in behavioral genetics are. Every time you hear a news article that says, "Gene for depression found," I want you to think about this case.

Risch et al. performed a meta-analysis on 14 studies that were looking at Serotonin Transporter (5-HTTLPR) genotype and number of stressful life events. These two factors were related to the subsequent risk for developing clinical depression. Their analysis found -- contrary to a very well known study, Caspi et al. -- that there was no association between genotype for this gene and depression risk and no significant interaction between genotype and number of stressful life events.

I think this case is a good example of why we should be skeptical of behavioral genetics studies reported in the news until they have been replicated repeatedly.

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Evil Genes: Why Rome Fell, Hitler Rose, Enron Failed, and my My Sister Stole My Mother's Boyfriend

Dec 04 2008 Published by under CNS Diseases and Disorders

When I was asked to review Evil Genes: Why Rome Fell, Hitler Rose, Enron Failed, and my My Sister Stole My Mother's Boyfriend, by Barbara Oakley, I was pretty certain that my life as a Science Blogger had reached its peak. I mean, blogging about science AND FREE BOOKS?! You're not serious. When I got the book in the mail I did a little happy dance of joy. It's the little things in life, you know.
And then, of course, I realized I would have to review it. Luckily, for this particular book, it turned out to be a very easy task. For another, excellent review, check out Gene Expression's coverage.

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Complete speculation on the health of John McCain

Some people have been noticing erratic behavior from republican nominee John McCain lately. His most recent seems to be slight, but rather odd. Specifically, he appears to have developed ptosis--- a drooping eyelid--- which could of course be related to any number of causes, from an autoimmune attack on cholinergic receptors such as that seen in myasthenia gravis, to diabetes.
Ptosis can also be the result of a brain tumor that affects the oculomotor nerve (cranial nerve III). Sudden development of the condition at old age following multiple bouts of melanoma (which has a penchant for metastasizing to the brain) would seem to be cause for concern, so I wonder if any neurologists would like to weigh in?
McCain also seems to be hiring a very expensive makeup artist who may be assisting in the coverup of the condition. I really, really wish he'd release his medical records in full so that people can stop speculating about the ramifications of a chronically ill president with a potentially untreatable brain tumor, and his vice president with all the foreign policy experience and political saavy of a Hun.

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