neurodudes

Doctors Struggle to Treat Mysterious and Unbearable Pain - New York Times

Hadn’t heard about this before:

[...] she felt a sudden pop in her hamstring. “It felt like a guitar string had been plucked and it had broken,” said Ms. Toussaint, who is now 45.

An intense burning sensation followed; it felt as if her leg had been doused in gasoline and set on fire, she said. The next day, the college athletics trainer determined that she had pulled her hamstring. But even years later, the pain would not subside. It migrated to her other leg, leaving her bedridden for nearly a decade, and overtook her vocal cords, leaving her temporarily mute.

All the while, doctors puzzled over and even doubted her mysterious condition.

Ms. Toussaint now knows that she is among an estimated one million Americans living with complex regional pain syndrome, a nerve disorder formerly known as reflex sympathetic dystrophy syndrome. For patients with the disorder, a trauma as mild as a fractured wrist or a twisted ankle can cause the nerves to misfire, so much so that intense pain messages are constantly sent to the brain.

Interestingly, neural stimulation only provides a short-term benefit with eventual adaptation. In some cases, ketamine administration (enough to put the patients in a temporary coma) has completely stopped the pain. Ketamine is an anesthetic (although it has been known to actually stimulate circulation at certain doses) with well-known psychedelic properties. It is also a non-competitive NMDA antagonist that is often used in conjunction with traditional opiods for an analgesic effect.

I wonder if this effect is simply due to the interaction with the NMDA receptor or is something more complex. (For example, the analgesic effects of ketamine when combined with a opiods seem unrelated.)

Here’s a link to the original paper in the journal Pain, which suggests that CRPS patients have suffered damage to small-diameter PNS nociceptive fibers.

Technology Review: Emerging Technologies and their Impact

I don’t know too much about Zach Lynch, other than that he has a blog and refers to his company as the “neurotechnology market authority”, but there are some interesting tidbits from the TR interview:

TR: Research suggests that antidepressants are effective partly because they stimulate neurogenesis. So companies such as BrainCells, based in San Diego, CA, are screening compounds that promote growth of neural stem cells in the brain. They say these drugs could bring new therapies for depression and, eventually, neurodegenerative diseases.

ZL: It’s an exciting area, and the investment community is certainly interested. But the jury is still out.

TR: We’re also starting to see a new kind of therapy for brain-related illnesses — electrical stimulation. Various types of stimulation devices are now on the market to treat epilepsy, depression, and Parkinson’s disease. What are some of the near- and far-term technologies we’ll see with this kind of device?

ZL: We’re seeing explosive growth in this area because scientists are overcoming many of the hurdles in this area. One example is longer battery life, so devices don’t have to be surgically implanted every five years. Researchers are also developing much smaller devices. Advanced Bionics, for example, has a next-generation stimulator in trials for migraines.

In the neurodevice space, the obesity market is coming on strong. Several companies are working on this, including Medtronics and Leptos Biomedical. In obesity, even a small benefit is a breakthrough, because gastric bypass surgery [one of the most common treatments for morbid obesity] is so invasive.

In the next 10 years, I think we’ll start to see a combination of technologies, like maybe a brain stimulator that releases L-dopa [a treatment for Parkinson's disease]. Whether that’s viable is a whole other question, but that possibility is there because of the microelectronics revolution.

The real breakthrough will come from work on new electrodes. This will transform neurostimulator applications. With these technologies, you can create noninvasive devices and target very specific parts of the brain. It’s like going from a Model T to a Ferrari. Those technologies will present the real competition for drugs.

Take 10 Years Off My Face, in 60 Seconds - New York Times

Relevant details:

The company says the freezing effect comes from two ingredients: gamma aminobutyric acid, a substance found in the human nervous system that can block signals between nerves and muscles, and gynostemma pentaphyllum extract, derived from an herb used in traditional Chinese medicine. The company contends that gamma aminobutyric acid, a molecule that stays on the skin’s surface, activates smaller gynostemma molecules and sends them through the skin, where they signal muscles to relax, according to Gene Beilis, a pharmacist who is the vice president for product development at Freeze 24/7.

But the company has no scientific evidence to back up its claim that its products actually affect facial muscles.

And further down:

Mr. Beilis agreed that gamma aminobutyric acid is a powdery substance that coagulates when it dries, gripping the skin in place. Another ingredient in the product, eugenol, a clove derivative used in dentistry as an analgesic, “gives you a cool, numbing, tingling sensation,” he said.

Platelet-Derived Serotonin Mediates Liver Regeneration — Lesurtel et al. 312 (5770): 104 — Science

Although it is not suggested by this paper (which was brought to my attention by F1000 biology), I’d like to suggest this as a very, very naive hypothesis: That some part of the anti-depressant effect of SSRIs could be mediated by their ability to promote liver regeneration, as the above Science article suggests. The paper itself details how 5HT-2A and 2B receptors are upregulated during regeneration and how 2A & 2B antagonists slow regeneration.

There is some evidence for a connection between liver disease and depression. (Also, traditional chinese medicine views depression as a disease of the liver.) Without a doubt, the liver plays a well-established role in general detoxification.

Although I have no evidence to suspect it, I think it would be interesting to see if the SSRIs were leading to increased liver serotonin, resulting in liver regeneration and hence less depression.

Does Eating Salmon Lower the Murder Rate? - New York Times

Neat stuff on the role nutrition can play in brain function… it surprises me that the effect can be so large.

Most prisons are notorious for the quality of their cuisine (pretty poor) and the behavior of their residents (pretty violent). They are therefore ideal locations to test a novel hypothesis: that violent aggression is largely a product of poor nutrition. Toward that end, researchers are studying whether inmates become less violent when put on a diet rich in vitamins and in the fatty acids found in seafood.

Shannon Moffett, author of The Three Pound Enigma [book website; Amazon], was kind enough to send us a copy of her book to review. To be honest, when I first took a look at the book, I was pretty sure that — while it might be a great, general-neuroscience-interest book for the public — it would certainly not appeal or be informative for the specialist in our Neurodudes audience. Now, after reading her wonderful book, I realize how wrong I was.

Full review is after the jump.
(more…)

This article in the latest issue of the Journal of Neuroscience is interesting in the sense that they are do human brain stimulation of the hypothalamus, for the treatment of cluster headaches - but they then do positron emission tomography (PET) to examine the downstream neural circuits responsible for the abolition of the perception of headache.

Hypothalamic Deep Brain Stimulation in Positron Emission Tomography

This moves the field of brain stimulation from simple stimulate-and-see-what-happens, towards more of a study of human neural circuitry and how stimulation drives activity in connected locations. It’s possible this will lead, in the future, to better and more focal stimulation protocols, as people figure out what the “circuit-level” phenomena are that correct particular aspects of neural dysfunction. Perhaps someday we will have a map of the “hot spots” where stimulation of a small chunk of matter can modulate a wide degree of neural circuitry for the better.

(Last year, Helen Mayberg and colleagues’ deep-brain-stimulation-and-depression paper got at this issue as well, in which they stimulate the cingulate and (perhaps surprisingly) sent depressed patients into remission, and furthermore changed the activity of frontal structures from the abnormal state, back to a more normal pattern of activity.)

These studies are perhaps setting a good precedent for brain-stimulating neuroclinicians to follow.

— Ed

Artificial limbs that walk naturally

Not too much info about the device, but basically, without any active electronics, the foot has a natural enough gait that people do not notice it is a prosthesis. Pretty cool.

Nerve Stimulation and Revenue Growth - New York Times

Some interesting tidbits about the backroom financial manueverings of some vagus nerve stimulator startups. Hadn’t heard of Advanced Neuromodulation Systems before.

The Pablo Picasso Alzheimer’s Therapy - New York Times

Interesting connection: Art appreciation seems to ease Alzheimer’s symptoms. Less memory loss. Less repetition.

Super interesting… there’s a lot to say here. There are of course many documented cases of particular brain lesions causing marked changes in personality or hobbies. But this appears to be something different. There is both an interest change (ie. people are more interested in art) but the neurological disease itself is somehow lessened (temporarily) by the interest itself.

The article mentions that there is very little research in the area. Does anyone know of any studies? It’s fascinating to think that such a simple, non-invasive therapy could be so powerful.

Either that, or it just means that art critics (”It’s like he’s trying to tell a story using words that don’t exist” — critic or patient?) have something in common with those with neurodegenerative disease.