neurodudes

Neuroscientists often use mouse models to understand learning and neural disease. Much of our understanding of mammalian biology comes from these amazing animals. It is commonly said that highly inbred lab mice are unintelligent. But is it true for wild mice too? In a talk last week at Harvard, Karl Svoboda referred to this fascinating YouTube video showing a mouse trained to complete an obstacle course:

Other training videos from the same trainer are available along with an official website with interesting tips about mouse training. Perhaps highly inbred lab mice are unable to replicate such feats but it is amazing to see in what detail this trainer understands mouse behavior and development:

An absolute necessity for any pet training is to understand the animal’s needs and to know about its generic behaviour, since appropriate animal training is only based on certain natural habits. For mouse agility, this means e.g. their great spatial orientation abilities and spatial memory which is worth bringing to light by relevant trick training. In nature, mice always prefer the familiar (= safe) route to their feeding site, no matter if it’s a long way round. This is also the reason why mice are unbeatable in maze tests – and a mouse agility course is nothing else than a maze without walls!
But many owners forget that if you expect your pet to show some natural habits and abilities, first and foremost the husbandry has to be species-appropriate. If your mice have to live in a small ground level cage, their three-dimensional consciousness and orientation abilities will surely be stunted or never fully develop.

Brain, Machine and In-Between from Nature Opinion forum on Nature Network

Nature sent me a press release about this today and it seemed like it might be of interest to ND readers. There is also a related commentary in the journal this week.

Apparently, in a few years, we will be able to bring Neaderthals back to life with the complete Neaderthal genome [NYT]. Currently, there is good sequence data available over 63% of the genome. (I’m amazed that, given fragmented DNA from bone, Neanderthal sequence can be distinguished from human DNA contamination but perhaps this problem is solved by having high enough coverage/multiple fragments of the same region.)

Also, it looks like Neanderthals share the FOXP2 variant that humans have:

Archaeologists have long debated whether Neanderthals could speak, and they have eagerly awaited Dr. Pääbo’s analysis of the Neanderthal FOXP2, a gene essential for language. Modern humans have two changes in FOXP2 that are not found in chimpanzees, and that presumably evolved to make speech possible. Dr. Pääbo said Neanderthals had the same two changes in their version of the FOXP2 gene. But many other genes are involved in language, so it is too early to say whether Neanderthals could speak.

UPDATE: A few days ago, I heard Wolf Enard, one of Paabo’s postdocs, speak on a fascinating project, where human version of FOXP2 was knocked in to mice (replacing the endogenous mouse version). Although the phenotypic effects were subtle, the approach itself is quite revolutionary: Putting human versions of genes into model organisms to see how the subsequent evolution of the gene changes its function. I wonder what other genes might be amenable to this approach.

PNAS has some interesting articles that I came across today:

1. 3D PALM (open access): Using 2-photon and photoactivatable proteins, the authors image beyond the usual sub-wavelength TIRF limits. They image over multiple microns with 50nm resolution.
2. Neuroeconomics:  Low digit ratio (2d:4d) predicts financial success in traders. Okay, measure the length of your index and ring fingers. (Not sure if this analysis applies for the ladies; the authors only used men in the study.) Calculate the ratio (2d/4d); longer ring fingers signify greater fetal androgen exposure. The mean value is about 0.96. As the authors say,
   

   Digit ratios have been found to predict performance in competitive sports, such as soccer, rugby, basketball, and skiing, so 2D:4D may also predict the risk preferences and physical speed required for high-frequency trading.

   A strong correlation (r~0.5) was found between low digit ratios and profits in short-term trading. So, they take on more risk and make more money. What I want to know is how well the low 2d:4d ratio traders did over the last 6 months!

Nature is reporting on potential flaw in multiple imaging (fMRI) studies of social neuroscience. Ed Vul (a graduate student in my dept) and colleagues have a paper in press that says that many of the high correlations between brain regions and social behavior are implausible, given the inherent variability/noise in fMRI. Furthermore, based on a survey of methods from individual investigators, they created a list of papers that commit, in their view, a statistical mistake (non-independence). Naturally, the authors named in the paper aren’t happy and, according to the Nature article, several rebuttals are in the works. At the very least, to my non-expert eyes, this seems like an important discussion to have about data analysis and methodology.

As the first presidential debate nears, there’s a lot of excitement (and worry) regarding the election. Today, Salon had an interesting piece on voter behavior and irrational attachment to ideologies and candidates. Recounting a recent psychology paper’s punchline:

The article’s conclusion should be posted as a caveat under every political speech of those seeking office. And it should serve as the epitaph for the Bush administration: “People who lack the knowledge or wisdom to perform well are often unaware of this fact. That is, the same incompetence that leads them to make wrong choices also deprives them of the savvy necessary to recognize competence, be it their own or anyone else’s.”

Slate had a story (“Why is every neuropundit such a raging liberal?“) about how neuroscience and neuromarketing are changing political consulting (also here’s a link to a similar story in NYT last week):

According to a study of political psychology published last Thursday in Science, conservatives tend to be the jumpier lot.

The researchers called 46 political partisans into their laboratory at the University of Nebraska, affixed electrodes to their fingertips and eyelids, and measured sweat output and eye blinks in response to a series of startling stimuli. (Subjects were forced to endure images of bloody faces and maggot-infested wounds, as well as sudden blasts of white noise.) The results: Social conservatives—those who supported the death penalty, the Patriot Act, prayer in school, and the like—sweated more, and blinked more intensely, than the liberals.

The Slate and NYT articles in particular suggest something that I have long believed to be true. The Republican “story” is, from a neuroscience perspective, simply better because it tends to view the world in clear-cut terms with no middle ground and, thus, is more effective at rallying emotional processing areas of the brain (eg. limbic system). It is well-known in neuroscience that emotionally salient events that activate these limbic structures are better remembered than less charged memories. The Democratic “story” tends to be more complicated with shades of gray and therefore requires higher-level processing (eg. cortical areas involved in conflict resolution). Clearly, I’m oversimplifying things here a bit (see, I’m designing this post to appeal to your limbic system!) but I think that this hypothesis might have some legs.

Of course, if it’s true, why doesn’t everyone vote Republican if that story is the neurally more rewarding one? Or perhaps the more relevant question: Is it even possible for the Democrats to tap into the similar evolutionarily older limbic structures that seem to dominate the Republican story?

Also, although I prefer Neurodudes to stick with the science over any partisan politics, I must say I found this statistic interesting (from the Slate article):

in 2002, Daniel Klein and Andrew Western tallied the political affiliations of professors at Berkeley and Stanford and found that even in the hard sciences, Democrats outnumbered Republicans by a factor of almost 8 to 1. Among professors of neurology and neuroscience, Klein and Western counted 68 registered Democrats against just six Republicans.

Plants Found to Show Preferences for Their Relatives – NYTimes.com

Two amazing things here:

1. 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:
   
   
2. 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?

Nytimes article.

Summary after the break.

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The concept that the brain holds maps of the surface of the body in the primary sensory and motor cortex is a fascinating but well known fact to the field of neuroscience since the early work of Wilder Penfield. What is less broadly appreciated is the concept of “peripersonal space”. A new book by Sandra and Matthew Blakeslee describes peripersonal space in the following way:

The maps that encode your physical body are connected directly, immediately, personally to a map of every point in that space and also map out your potential to perform actions in that space. Your self does not end where your flesh ends, but suffuses and blends with the world, including other beings. [...] Your brain also faithfully maps the space beyond your body when you enter it using tools. Take hold of a long stick and tap it on the ground. As far as your brain is concerned, your hand now extends to the tip of that stick. [...] Moreover, this annexed peripersonal space is not static, like an aura. It is elastic. [...] It morphs every time you put on or take off clothes, wear skis or scuba gear, or wield any tool. [...] When you eat with a knife and fork, your peripersonal space grows to envelop them. Brain cells that normally represent space no farther out than your fingertips expand their fields of awareness outward, along the length of each utensil, making them part of you.

What I appreciate about this, besides the stretchy comic book characters that it makes me think about, is that it provides a powerful perspective to begin piecing together a mass of disparate neuroscience data, which the Blakeslee’s capitalize on.

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In the new issue of PNAS, a totally awesome discovery about an infrared inter-species signalling system:

Ground squirrels not only heat up their tails to deter snake attacks — but they also seem to use the strategy selectively against infrared-sensitive snakes — leading us to the ultimate conclusion that when the bees are gone, the squirrels will inherit the earth…

You can check out an infrared-eye-view of squirrel/snake battles here because I don’t know how to post movies on the internet yet

–Davie