Whistler Blackcomb, here I come…
Please excuse the interruption while I have the most fun of my young life. Normal posting schedule should resume after New Year’s.
Willem Dafoe, Will Ferrell and Andy Richter star in this comedic gem. Enjoy:
Yaawwwn. According to conventional wisdom, we get sleepy after Thanksgiving dinner because of the high tryptophan content in turkey. Tryptophan is an essential amino acid that serves as a chemical precursor for serotonin, a vital neurotransmitter involved in mood and wakefulness.
There are many studies demonstrating serotonin’s sedative effects, but I want to take a minute to highlight a paper that implicates serotonin in social cognition.
Wood et al. measured social behavior using a monetary prisoner’s dilemma game in which subjects thought they were playing against other people (in fact they were playing against a computer that utilized a standardized tit-for-tat strategy against each subject). If subjects were kept on a diet low in tryptophan, they demonstrated less cooperativity in their decision making. When subjects were given a drink with high tryptophan content before playing the prisoner’s game, they were more likely to cooperate with their automated partners.
It’s exciting to think that that something as mundane as diet can significantly modulate economic decision making. Maybe it will inspire CEOs to start dosing the the water cooler with tryptophan before attempting to broker a delicate merger. However, such scenarios are not entirely analagous to the study at hand because Wood et al. deprived subjects of tryptophan prior to behavioral testing, whereas most adults are unlikely to enter an important business meeting on an empty stomach.
The title of this post is also misleading because there’s not much evidence that eating turkey increases the concentration of tryptophan in your brain. Zack Lynch of Brain Waves does a nice job of busting this myth, so I’ll just direct you there instead of re-hashing the argument.
When news sources first picked up a bizarre story about a plastic bag containing a brain found near an apartment complex, nobody knew if the specimen came from a human or an animal. Now, the medical examiner’s office in Richmond, VA has reported that the brain does not come from a human. But this begs the question, how do you know what species a brain comes from?
Size, for one thing. The average human brain weighs in at about 1.35 kg. Despite the fact that humans have the highest brain size:body weight ratio (also known as the encephalization quotient, or EQ), we don’t actually have the largest brains. For instance, a sperm whale’s brain weighs in at a hefty 7.8 kg. That having been said, the only animals with brains that could be confused with a human’s are the dolphin and walrus, whose noggins weigh in at 1.55 and 1.07 kg respectively.
However, unpreserved brains tend to shrink in size, and general morphology may no longer serve as a useful indicator of the species of origin. In this case, biochemical methods can provide more accurate information. These assays have been especially useful in the food industry, where it is important to know which animals’ tissue are present in the final product.
While protein content can provide important clues regarding the identity of the species in question, DNA analysis is preferable. Specifically, the rapidly evolving mitochondrial genome (mtDNA) differs widely between species. In 1989, Kocher et al. showed that universal primers could be used to amplify mtDNA coding for the cytochrome b protein from a variety of animals. Treating these segments with restriction enzymes yields fragments of characteristic lengths that can be used to deduce the species to which the tissue belongs. While the fragments are meaningless by themselves, they can be compared to reference samples from different species in order to find a match.
So the next time a brain turns up on your doorstep, you’ll know how to find out if it’s human.
It is not uncommon for men to feel embarrased about their stamina in the sack. The question, “How short is too short?” lacks an objective answer, but it is generally agreed that an intravaginal ejaculation latency time (IELT; a great acronym, though not the greatest) of less than 2 minutes leaves something to be desired. Unfortunately, Alfred Kinsey’s research in the 1950s showed that most men fail to meet this relatively generous benchmark.
Over the years, numerous therapies have been devleoped for premature ejaculation (PE). Some of these involve behavioral modification, such as the traditional Stop Start Technique. Others involve a local anesthetic like Benzocaine, though condoms containing this compound receive mixed reviews.
Though the ejaculatory reflex is mediated by neurons in the spinal cord, it is also amenable to cognitive control by brain regions such as the nucleus paragigantocellularis. A new generation of psychoactive PE medications is inspired by anti-depressants that inhibit reuptake of serotonin (SSRIs). Inibiting reuptake increases the concentration of serotonin at the synapse, which is thought to be critical for ejaculatory control.
Unlike anti-depressants, it is desireable for PE medications to be fast-acting and have a short half life. Science Daily reports on a clinical trial of dapoxetine, an SSRI with these properties. Giuliano et al. show that dapoxetine, taken only a couple hours prior to intercourse, increases mean IELT by several minutes. It’s no miracle cure, but it helps.
On the other hand, some people are proud of their..ehem..efficiency. Dave Chapelle appears to be one of them (note: adult language).
If you want your child to become a brilliant scientist, you might name him or her after someone famous like Einstein or Newton.
Or you could be less subtle about it. One of the authors on this paper is named “Just Genius.”