It’s been a long time since my last post, so I figured that my loyal readers (are you out there?) deserve some kind of explanation. As I may have mentioned before, I am about to apply to a bunch of Medical Scientist Training Programs (MSTP) in the hopes of earning both an MD and a PhD in neuroscience. Unfortunately, that means that every moment of free time that used to go here now goes toward the behemoth that is the MCAT. Now I’m one month away from Test Day, and I look forward to resuming my normal posting schedule after this is all over. In the meantime…
…Wish me luck.
If you haven’t seen the preview for Hollywood’s latest horror flick Awake, they are worth checking out on YouTube. The movie is about a man undergoing heart surgery who experiences “anesthetic awareness,” a phenomenon wherein the patient is paralyzed but partly or fully conscious of the surgical procedures and conversations taking place.
The condition is most likely to occur when patients are given drugs that block signaling at the body’s neuromuscular junctions, leading to paralysis. These drugs are given during delicate surgeries in which the patient cannot be allowed to move. Normally neuromuscular blockers are given in combination with an analgesic that blunts sensation, but insufficient administration of the analgesic can bring about awareness even though the patient still appears to be knocked out to the naked eye. In real-life, doctors prevent this from happening by using EEG to monitor the patients’ brain activity levels.
Anesthetic awareness makes for a great plot device, but unsurprisingly the movie inflates the risk factor. While the trailer claims that 1 in 700 patients experience this seemingly horrifying condition, this article in Slate takes a closer look at the numbers and finds the real incidence to be 1 in 14,000.
My heart tells me that I should be in San Diego for the annual Society for Neuroscience conference, but unfortunately I’m here holding down the fort while nearly all the other members of my lab are gone. I’m crossing my fingers that I will get to join the fun next year. In the meantime, I have been keeping up with the goings on in San Diego thanks to a few intrepid live-bloggers. You can keep a tab on the year’s finest neuroscience research by heading to these sites:
The Times Online has a nice little article on the neuroscience of free will and the place of scientific findings in the courtroom. It’s similar to the fantastic article that the New York Times ran a couple months back.
My inclination is to agree with the first commenter on the Times Online article. The main insight provided by neuroscience should be that guilt, personal responsibility, and punishment are outdated concepts. Because we can no longer distinguish between the person and the body, we have to start doling out prison sentences as practical measures, not a moral ones. The role of the courts and prison system should be rehabilitative and deterrent, not punitive. Well that’s my two cents at least.
Yes, that’s the headline we’ve all been waiting for.
Scientific American reports on a recent study from the Journal of Neuroscience in which researchers fed rats on low (2.5%) or high (5%) ethanol diets and then tested their performance on two memory tasks. The first involved novel object recognition, in which the rats are first exposed to a pair of identical objects and then exposed to one of the familiar objects and one novel object. The percentage of time spent investigating the novel object is considered an index of memory, not entirely unlike looking the looking time tasks that are used with human infants. The second task involved training the rats with a footshock in one of two compartments and then testing the degree to which they avoided this compartment in subsequent testing.
On both tasks, rats consuming the 2.5% ethanol diet performed better. Rats consuming the 5% ethanol diet maintained superior performance on the fear conditioning experiment but performed worse on novel object recognition.
The researchers also tested rats with a dysfunctional copy of the NR1 subunit of the NMDA receptor. In contrast to wild type animals, the mutants did not exhibit increased memory function in in response to moderate ethanol consumption. This suggests that alcohol’s beneficial effects are mediated through NMDA receptors, akin to the beneficial effects of fasting.
The authors stress that 5% ethanol had neurotoxic effects on the rats that consumed it, including reduced neurogenesis and NR1 expression. They propose an inverted U function for alcohol’s facilitatory effects on cognition, as diagrammed below:
So, like I always say when a study like this comes out, everything is good in moderation.
Today is Yom Kippur, the Jewish Day of Atonement. As is customary, I am observing the holiday by fasting for 24 hours. Supposedly, this self-denial will bring me closer to God and help me earn forgiveness for my sins. Needless to say, it’s pretty uncomfortable and most other days I eat to my heart’s content.
However, some people choose to fast for reasons other than eternal salvation. Caloric Restriction (CR) is a recent trend in which dieters limit their total calorie intake in order to improve their lifespan. Studies show that low calorie diets and intermittent fasting can significantly increase the lifespan of some animals and prevent the progression of neurodegenerative diseases like Alzheimer’s. CR has many critics, some of whom compare the practice to anorexia.
A new paper in the Journal of Neuroscience suggests that caloric restriction also improves baseline brain function. Fontan-Lozano et al. fed one group of mice ad libitum and another group of mice only on alternate days. They found that the mice subjected to intermittent fasting performed better on behavioral and electrophysiological measures of learning. This improvement was associated with upregulation of the NMDA receptor subunit NR2B and was reversed by application of a NR2B antagonist.
It is tempting to speculate about the evolutionary significance of fasting-induced cognitive enhancement. If food is rare in a given environment, then remembering how to access these limited resources would be an extremely adaptive trait.
It remains to be seen whether similar cognitive enhancement is observed in humans. If so, I may start observing Yom Kippur more frequently.