Sunday, March 16, 2014

Hyperbaric oxygen treatment decreases inflammation and mechanical hypersensitivity in an animal model of inflammatory pain RSD

Wilson HD, Wilson JR, Fuchs PN Brain Res vol. 1098126 - 1282006



Hyperbaric treatment was initially developed to combat the adverse effects of deep sea diving. In recent years, hyperbaric oxygen treatment has been used to treat a broad spectrum of ailments, including delayed-onset muscle soreness, fibromyalgia, and complex regional pain syndrome (CRPS). However, limited data are available on the effect of hyperbaric oxygen treatment on inflammatory pain. The effect of hyperbaric oxygen treatment on carrageenan-induced inflammation and pain in rats was investigated. It was hypothesized that treatment with hyperbaric oxygen would decrease paw edema and hyperalgesia in an acute inflammatory pain model as compared with that of a sham-treated control group.


The experiment was conducted on 44 male Sprague-Dawley rats each between 300 and 350 g. The inflammatory pain condition was induced by subcutaneous injection of 1% carrageenan suspended in saline in the left hind paw. Paw volume was assessed via water displacement with a plethysmometer, and percentage differences were calculated on the basis of posttreatment measures compared with pretreatment measures. Hyperalgesia was assessed using the up/down method of mechanical paw withdrawal thresholds. Hyperbaric oxygen treatment involved exposing animals to 100% oxygen at a pressure of 2.4 atmospheres absolute (ATA) for 90 minutes in a hyperbaric chamber. A control group was placed in the hyperbaric chamber but did not receive treatment.

Results: A 1-way analysis of variance revealed no significant preinjec-tion group differences. An overall mixed-design analysis with 2 group levels (treatment, sham) and 7 levels of time revealed a significant main effect for group, a main effect for time, and a group by time interaction. In the hyperbaric oxygen treatment group, paw edema remained at pretreatment levels immediately after treatment and continued to decrease slightly until 2 hours posttreatment, at which time it began to decrease. However, antinociceptive effects were apparent immediately after treatment and continued to increase up to 5 hours after treatment, suggesting that distinct mechanisms might be involved in the anti-inflammatory and antinociceptive properties of Hyperbaric Oxygen Treatment

.Conclusions: Hyperbaric oxygen treatment significantly reduced inflammation and pain after carrageenan injection in this rat model of inflammatory pain. Hyperbaric oxygen may be used in patients for whom nonsteroidal anti-inflammatory drugs are contraindicated or for those with persistent inflammation. www, 909.477.4545


Wednesday, March 5, 2014

Bradley VoytekBradley Voytek
Ph.D. neuroscience, UCSD Asst. Professor Cognit... (more) 
247 Votes by Paul King (Computational Neuroscientist, Redwood Center fo...), Aaron Kucyi (PhD Student in Neuroscience), Shan Kothari, and 244 more.
Before explaining this, I want you to try a quick experiment for me: hold your hand in front of you, fingers straight and pointing upward. Now, flex your index finger and justyour index finger. Did your middle finger flex, too? Maybe your ring finger even twitched a little? Try flexing just your ring finger. Unless you're a piano or string instrument player, it's unlikely that you were very successful at doing so.

The reason why that happens is closely related to why you can't control your individual toes. Stick with me.

This sexy beast is the motor homunculus:

He's built to reflect the relative area in the motor cortex that is devoted to controlling specific muscle groups. Notice how overrepresented the hands, lips, and eyes are and how underrepresented the arms, legs, and feet are?

Here's the motor cortex in the brain:

Basically, the more motor cortical area devoted to a region, the greater and finer the voluntary control over those muscles groups that we have.

Originally this map was created by Canadian neurosurgeon Wilder Penfield in 1937. Penfield pioneered brain surgery on awake patients. He  would use a small electrical stimulator to map out different parts of the brain, which is still done by neurosurgeons to this day. The logic was simple: stimulate a part of the motor cortex and watch which parts of the body twitched. This gives a mapping between brain and body, and what he found was a clear topography in the motor cortex.

Journalist and science writer Mo Costandi wrote an amazing history of Penfield here that's well worth reading, by the way:

As I said in my answer to:

Are all the wrinkles on a brain's cortex the same across people?

...neurosurgeons will perform electrical stimulation mapping of awake people if they have to remove any brain tissue near what they call "eloquent cortex"... [because] [t]he only way even an experienced surgeon can be sure that specific brain area in a specific person is motor, or speech, or sensory, is via this mapping technique... This is because, although gross neuroanatomical features are generally conserved across people, there can be a huge range of variation.

Penfield used a highly invasive means to map out the motor homunculus. But it turns out we have some pretty cool modern technology with which we study the motor cortex non-invasively: Transcranial Magnetic Stimulation (TMS).

TMS induces an electrical current using a rapidly changing magnetic field