I’ve been swamped with work, so I haven’t had time to write original pieces for the blog. This will come soon enough, in the meantime, here’s some sciency stuff you might like.
In case of a spider apocalypse, wear red
Webvision reports on a fascinating study in Science on the use of defocus as a cue for depth in jumping spiders. Jumping spiders have two layers in their retina that are sensitive to visible light, but only the deepest one receives focused images. The defocus information could be used as a cue for depth, and this is confirmed by messing with the spider’s depth perception by varying the spectral content of light from green to red. Read the post, then the original article.
In this month’s Nature Neuroscience, Anikeeva et al. report on the optetrode, a tetrode supported by an optic fiber that can be used to record electrophysiological signals while simultaneously stimulating the underlying area with light. This optogenetic solution is small enough to be implanted and used in freely moving animals, and perhaps best of all, it can be built for a few hundred dollars in an afternoon. Also in this month’s Nature Neuroscience, Greg DeAngelis and Dora Angelaki write about Bayesian fusion of sensory signals in neurons sensitive for both optic flow and vestibular signals in area MST.
Equacy versus ecstasy
David Nutt is psychiatrist and researcher at Imperial College London. He worked for a while in an independent committee set up by the British government to evaluate drug policy. At one point he wrote an article in Psychopharmacology evaluating the relative danger of ectasy (MDMA) and equacy (horse-riding), finding that all else being equal legal activities like horse-riding frequently have dangers similar or greater than the consumption of a class A drug like ecstasy. He also wrote two famous articles in The Lancet about rational drug policy. He was fired from this job after giving a lecture on the absurdity of UK drug policy. Among the really interesting and convincing findings he shows are the fact that drugs are subject to economic pressures like anything else; in the brief interval that it was legal in the UK, mephedrone displaced cocaine as a stimulant of choice with positive consequences, until it was made illegal after tabloid scares.
Going NUTS for STAN
Andrew Gelman has unveiled NUTS, the no U-turn sampler which is (as I understand it) a variant of Hamiltonian Monte Carlo (HMC) that doesn’t require tuning. It’s incorporated into the STAN software. Here’s some critiques of this work from Radford Neal.
And on a completely different note
Here’s a video of flying fish: