There has been a few articlesrecently in the NYT about the neural mechanisms used by mosquito repellents. What a wonderful idea: Do some ephys recordings to find which neurons are sensitive to DEET (the current standard for mosquito repellents, which I can attest both doesn’t work very well and eats holes in synthetic clothing) and then build targeted compounds for those receptors/neurons/pathways. I always like this type of simple and practical neuroengineering.
Right now, it appears that there’s a bit of controversy in the field. Earlier this year, in Science, a group from Rockefeller found that DEET masked sensitivity to human odors by interfering with a particular odorant receptor. This impressive result was recently question by entomologists from UC-Davis in a PNAS paper claiming that DEET acts directly on a particular olfactory receptor neuron and does not attenuate the response to the same human-emitted odorant, as found in the earlier paper. Although the results appear to be conflicting, the studies use different techniques and thus it is likely that DEET’s action might be more complex than either paper claims. Still, the idea of identifying a target for chemical intervention by looking at electrophysiological responses to DEET is smart.
In related work, earlier this year a group from Colorado State University, as described in this PNAS overview, “conducted a rigorous search of a library of N-acylpiperidines, using an artificial neural network to identify strong candidates, and then tested them in the laboratory on human volunteers.” They found a candidate molecule that has a ~4X longer repellency effect than DEET. Here’s a photo from the experiments (DEET vs. untreated hand)… ouch!
It has just been brought to my attention that for the last few months (!) neurodudes has had some serious problems with allowing users to comment, ie. commenting was completely closed. I am very sorry for that. The problem should be fixed and now commenting should again be easy for anyone to use. As always, feel free to contact us at contactus^neurodudes^com (replacing ^ as appropriate) if you have any questions or concerns. - Neville
Data portability is already available. According to the video, users can download the raw data from the 580,000 SNP array and do whatever they want with it.
The SNP array is 580,000 SNPs! Wow. I assumed that the number of genetic features was on the order of 100-1000, giving a rough haplotype.
Sharing/Web 2.0 features: The real power is 23andwe, an effort to data mine and leverage the power of a large database with many people’s genetic information. The founders mention that they want to contribute back to science and healthcare by surveying their customers behaviors and medical issues to uncover further correlations with genes. Like Facebook, the service becomes more valuable and more informative as the network grows.
Description of the talk from Google:
The 23andMe Personal Genome Service offers customers a glimpse at their own DNA sequence, a 750-megabyte string that functions as the operating system for a human being. Common variations in this code can influence the structure and function of the associated wetware in predictable ways. Some of these variations and their effects on traits such as athletic talent, pain sensitivity and avoidance of errors will be discussed in reference to three well-documented examples.
Although the shift away from liberalism amongst faculty is interesting, this graphic caught my attention:
Should we take this to mean that there should be more faculty jobs as the avg age increases? (Or is this negated by the fact that people are living longer and working longer?)
Plants missing photosynthetic enzymes of their own that migrate directionally toward “victim” plants. This behavior has an uncanny resemblance to axon guidance. Make sure to view the time-lapse video in the NYT article. Here’s an image from the PSU website:
Plants capable of identifying kin and “being nice” to kin while going into a competitive mode of root growth with non-kin. Amazing.
It refreshing to see this kind of interesting behavior without any neurons involved. It makes me think (realize) that the idea of a neuron or a neural system has many components and there might not be any good reason to assume that a single cell must have all of those properties or none of them. Something like a neuron-like cell that’s not a neuron in the classical sense. Anyone know of other examples?
Evaluating different 3D fluorescence microscopy techniques
Saw this on the Confocal list… Several times in the last few years I and others in the lab have debated the advantages and disadvantages of different fluorescence microscopy techniques. As many of you know, fluorescence microscopy is becoming increasingly important for manycoolneurosciencetechniques. But equally important in knowing how to properly image fluorescence.
Fascinating. The first case of a person with virtually perfect autobiographic memory. In the interview, she says that she runs her entire life through her head every day. Perhaps the difference isn’t in memory capacity but rather the automatic (unconscious) practicing of all past sensory experience.
This report describes AJ, a woman whose remembering dominates her life. Her memory is “nonstop, uncontrollable, and automatic.” AJ spends an excessive amount of time recalling her personal past with considerable accuracy and reliability. If given a date, she can tell you what she was doing and what day of the week it fell on. She differs from other cases of superior memory who use practiced mnemonics to remember vast amounts of personally irrelevant information. We propose the name hyperthymestic syndrome, from the Greek word thymesis meaning remembering, and that AJ is the first reported case.
“SPECT scans are not sufficiently sensitive or specific to be useful in the diagnosis of A.D.,” neurologist Michael Greicius , who runs the Stanford University memory clinic, and has a special interest in the use of functional brain imaging in the diagnosis of A.D., tells me. “The PBS airing of Amen’s program provides a stamp of scientific validity to work which has no scientific validity.”
Continued pontification on neuroethics issues after the jump. Read on »
Here’s a neat new website. It’s a repository of quantitative information on biological things (eg. organisms, biomolecules, etc.) Some stuff I found while glancing through:
Number of mRNA/cell in E. coli: 138
Volume occupied by all RNA in E. coli: 6%
Average gene length in mammals: 16.6kb
Average gene length in nematode C. elegans: 4 kb
Mutation rate per genome per replication in humans: 0.16 mutation/genome/replication
Average time between blinks in humans: 2.8 sec
Amount of photons necessary to excite a cone in humans: 100
Amazing. It looks like TTX (tetrodotoxin, a potent voltage-gated sodium channel blocker well-known to electrophysiologists) is not made by the pufferfish (which I had always assumed), rather it is from the bacteria/food consumed by the fish.
Decades earlier, another Japanese scientist had identified fugu’s poison as tetrodotoxin, a neurotoxin that leaves victims mentally aware while they suffer paralysis and, in the worst cases, die of heart failure or suffocation. There is no known antidote.
Researchers surmised that fugu probably got the toxin by eating other animals that carried tetrodotoxin-laden bacteria, developing immunity over time — though scientists then did not rule out the possibility that fugu produced the toxin on its own.
By this year, Mr. Noguchi had tested more than 7,000 fugu in seven prefectures in Japan that had been given only feed free of the tetrodotoxin-laden bacteria. Not one was poisonous.
“When it wasn’t known where fugu’s poison came from, the mystery made for better conversation,” Mr. Noguchi said. “So, in effect, we took the romance out of fugu.”
Aside from the interesting science, it appears there is also a small Japanese “industry” (de-ttx? detox?) seriously affected by TTX-free fugu. More after the jump Read on »
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