For new brain cells, go to the wild

For a while, people thought that vertebrate brains did not get new neurons throughout life. Songbirds provided one of the first known counterexamples, when it was discovered that some birds generated new neurons, associated with song centers, every year. Later, mammals were discovered to generate new neurons in adulthood, most interestingly in the hippocampus.

The hippocampus is deeply involved in all manner of learning and memory, but particularly spatial learning and memory. The natural hypothesis is making new neurons might be related to learning.

Demonstrating what causes new neurons to form is tricky, though. For example, one standard spatial learning test, the Morris water maze, is set up so that animals (rats, actually) that learn the task move around less (swim, actually) than animals that don’t learn the task. Learning and the physical activity are inextricably linked, so you cannot easily say which caused new neural growth.

Researcher Lara LaDage and colleagues tried to address this problem by using a different animal and a different learning task. Chickadees are very good at spatial learning because they store food in little hiding spots, and come back for it later. Many birds are dramatically better at these kinds of spatial memory tasks than humans.

LaGade and company captured a group of young chickadees (Poecile gambeli) in the wild, and split them into three groups.

1. Banded, let loose to live free in the wild, and recaptured three months later.
2. Captured and kept in in captivity for three months, where they were allowed to cache food and do associative learning.
3. Captured and kept in in captivity for three months, where they were not allowed to cache food.

A lot of the difficulty in running an experiment like this is trying to make sure everything is the same except one variable. With the free-living chickadees, you just have to accept that you can’t control everything. The trick is in making everything the same for the two groups of lab animals, a key one being keeping the animals’ general activity levels the same. LaDage and colleagues measured the chickadees’ perching in the lab, and were able to show they moved about the same distance, eliminating the confound between activity and learning.

All of this was done to see the impact on the brain. LaDage and colleagues identified new neurons by labeling a protein called doublecortin. Doublecortin shows up fairly specifically in new neurons, so by using an antibody to it, they could look in various regions of the hippocampus to see how many new neurons had formed in roughly the last month.

All the birds grew new neurons, but the free range birds had more new hippocampal neurons – both in sheer raw numbers and proportionately – than the captive birds allowed to cache food. The captive birds that cached food had more new neurons than the captive birds that did not cache food. A simplistic summary might be that animals’ brains show greater capacity to change and adapt when they get to be animals in the environment that natural selection has shaped them for.

Reference

LaDage, L., Roth, T., Fox, R., & Pravosudov, V. (2010). Ecologically relevant spatial memory use modulates hippocampal neurogenesis Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2009.1769

Picture by user jerryoldenettel on Flickr, used under a Creative Commons license.

When I’n not tweeting, I’m blogging; when I’m not blogging...

I am a shameless self-promoter.

Make your own cloud here.

More reality science ideas

Quite a while ago (Sometimes I forget how long I’ve been blogging), I wrote an article about reality television shows for scientists.

A while back, Bitesize Bio took up the torch with a new list of science reality shows we should have, but don’t. I particularly liked:

Research project with the stars: B-list celebrities become first year graduate students and experience rotating through three labs, presenting their work to their department and trying to meet all of the expectations of any other PhD student. Watch them struggle with error bars and statistics, freak out at the MSDS for dihydrogen monoxide and laugh at their tantrums when the acetone destroys their manicures.

Of course, I like this idea in part because of the cheap help in the lab...

Life in the holodeck

I’ve written a bit about how evolutionary theory might help resolve Fermi’s paradox. A new article by Geoffrey Miller in Seed focuses on another part of the Drake equation, culture:

I think the aliens don’t blow themselves up; they just get addicted to computer games.

Of course, as is often the case, the article really isn’t about SETI, but our own culture.
Post title pinched from bfchirpy.

Let’s get personal

The Dr. Jekyll & Mrs. Hyde blog had a quite good post on writing personal statements.

There’s a tricky thing about personal statements: It’s almost impossible to find good and bad examples of them. Because personal statements are part of competitive applications for programs or positions, they’re confidential, and rightfully so. It’s almost impossible to see how other people do them.

Thus, people don’t have an easy way to learn that something that is highly important to them personally – like having seen a close relative struggle with illness – is not that unusual. It’s easy for a professor or administrator to joke about the “grandmother story” being a cliché, but someone trying to write a personal statement for the first time has no easy way of knowing that their story is common.

The moral, for someone trying to write a personal statement, is to find someone who reads them regularly and get feedback before you send it off to that big program you’re interested in.

Shell shock: Is the new way to dispatch a lobster a better way?

When you’re a crustacean neurobiologist, cooking a lobster is a topic you’d better be familiar with, because you will be asked about it. (See posts in February 2005; May 2003; maybe this subject needs to get its own label.)

The Daily Mail has an article on the latest effort to deal with concerns that boiling lobster alive is inhumane. The title claims it’s a way “to kill a lobster with kindness.” This potentially more humane alternative to boiling?

Electrocution.

And it’s electrocution with a cutesy name. The device is called “CrustaStun,” which I’ll wager is supposed to be pronounced “cru-stay-stun” so that it rhymes with “crustacean.”

I never would have thought of electrocution as a means of killing a lobster, because earlier this year, I read a pair of papers by Robert Elwood and Miriam Appel relating to electricity and crustaceans. They were studying hermit crabs rather than lobsters, but most decapod crustaceans have very similar nervous systems and broadly respond to the same kinds of stimuli.

These two papers from these authors are a matched pair. Indeed, the two should have been combined into one paper. Each is very slight, with one experiment that is a variation of the other. In both, they implanted wires into the shells hermit crabs live in, so they could deliver small electric shocks to the hermit crab’s abdomen. In one (Appel and Elwood), they varied the intensity of the electrical stimulus. In the other (Elwood and Appel), they kept the intensity of the electrical stimulus the same, but gave the animals options for new shells to enter should they leave the shells they had been shocked in.

Hermit crabs are unarmored and do not like being outside of their shells. In both studies, they found the electric shock significantly changed the behaviour of the hermit crabs. The crabs left the shells they normally inhabit, and the authors saw some strange behaviours, including some aggressive behaviour directed at the shell. In other words, after getting a shock form the shell, some crabs started treating its shell like an enemy.

Elwood and Appel argue that their results show evidence for electrical shock eliciting pain responses in the hermit crabs. In the context of cooking lobsters, there is more experimental evidence supporting the idea that electric shock is noxious to crustaceans than evidence that high temperatures are noxious.

Nevertheless, there may still be an advantage to the new method in the speed. The Daily Mail article claims that:

The machine can knock a large crustacean unconscious in less than 0.3 seconds and kill it in five to ten. Crabs take four to five minutes to die in boiling water, while lobsters take three minutes.

I can’t help but think of the guillotine, which also had the goal of a quick, humane death. The actual practice of using the guillotine was, I understand, not always so tidy, and I wonder about how consistently the machine will accomplish its task.

The article claims in passing that this device this may improve the taste. I can think of no particular reason that should be, but the flavour issue is something I will leave for others to decide. But I do find it sad that a question that is so often asked generates strong opinions more than well designed experiments.

Reference

Appel, M., & Elwood, R. (2009). Motivational trade-offs and potential pain experience in hermit crabs Applied Animal Behaviour Science, 119 (1-2), 120-124 DOI: 10.1016/j.applanim.2009.03.013

Elwood, R., & Appel, M. (2009). Pain experience in hermit crabs? Animal Behaviour, 77 (5), 1243-1246 DOI: 10.1016/j.anbehav.2009.01.028

Is a syllabus that hard?

Things you rarely read on RateMyProfessors.com:

“This professor had a great syllabus.”

At a meeting about faculty development last week, a few people brought up “How to write a syllabus” as a skill that new faculty could benefit in receiving some instruction. This surprised me, because I never found putting one together to be particularly challenging. The main thing that students care about how they’re going to be evaluated, and I do think it’s important to spell that out.

Most of the rest of a syllabus is legal fine print, which does prevents instructors from screwing over students. But the fine print has been getting longer over the years. There’s why I don’t think a syllabus matters that much, because it’s not mainly about teaching or learning, it’s about administrative butt-covering. I am reminded of the TED talk below that discusses the relentless emphasis on creating standards, in which Barry Schwartz says.

Scripts like these are insurance policies against disaster. And they prevent disaster. But what they assure in its place is mediocrity.

Similarly, Johnnie Moore writes:

It often seems to me that everytime we experience a crisis, the solution is to write more rules. ... (T)he practical effect is to engulf people in explicit, complicated systems and reduce their freedom - based on an unconscious assumption that everyone is not to be trusted.

Has anyone encountered a lengthy detailed syllabus anywhere outside of formal educational institutions?

Come on, let me hear you sing with tailfeathers

Hummingbirds are amazing animals, but one of their less appreciated talents is their vocal abilities. Hummingbirds are one of the few animals that engage in vocal learning, for instance, which puts them in a small group with humans and a few other bird groups. The males learn songs because, as in other species, the lady birds find a good song... sexy.

Authors Clarke and Feo had previously shown that during courtship, male hummingbirds in one genus, Calypte (Calypte costae shown above; Calypte anna below) make sounds with their tailfeathers that are similar to sounds they make when singing. This paper tries to figure out how this particular signal evolved. One of the strengths of this paper is that they have four hypotheses about how the tail sound might have originated, three of which generate different predictions. The song and feather sound could:

1. Be unrelated as far as the female is concerned; two entirely different cues. If so, there would be no reason for the sounds to be the same as each other in the same species, or to be the same in different species.
2. Both be exploiting a female preference. If so, there is strong reason for the sounds to be the same as each other in both a single species, and between different species.
3. Have evolved sequentially, with female preference for one sound shaping the other. If so, you would predict the sounds to be the same in one species, but to differ between the two species.

Strong inference all the way, baby!

This paper does several things. One, they nail down exactly which feathers are responsible for the sound by experimentally removing feathers, and artificially running blasts of air over them. In both species, the same feathers make the sound, suggesting that both birds inherited this feature from their common ancestor. Interestingly, while hummingbirds outside the genus dive the females, few sing, suggesting that the diving is more ancient than singing in this group.

They also show that the tailfeather sounds of each species most strongly resembles that of the song made the normal vocal way. Interestingly, a hybrid between the two species generates a sound intermediate to the other two.

That there is an “intermediate” tail sound made by a hybrid suggests where we’re going with the matching. The two species make rather different sounds with their feathers. The differences in song patterns are fairly complex, but as a for instance, the sounds made by C. costae are around the 7 kHz range, whereas the sounds made by C. anna tend to be lower-pitched.

All of which suggests that one of the two sounds the males make evolved as a sort of “enhancement” to the earlier evolved sound. Given that singing seems to be the more recent innovation in this particular group of hummingbirds, it looks like the males started to sing to enhance the sounds made by their tailfeathers, rather than the song having primacy, as we might intuitively expect.

Reference

Clark, C., & Feo, T. (2009). Why Do Hummingbirds “Sing” with Both Their Tail and Their Syrinx? An Apparent Example of Sexual Sensory Bias The American Naturalist DOI: 10.1086/648560

Picture of C. costae by users Lance and Erin on Flickr, used under a Creative Commons license.

Picture of C. anna by user wolfpix on Flickr, used under a Creative Commons license.

Tuesday Crustie: “I hate a Barnacle as no man has done before”

Today is the 150^th anniversary of the publication of On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life by Charles Darwin. Although I’ve already featured a crustacean that Darwin collected, it seems appropriate to feature a couple more Darwinian crustaceans.

On his famed trip around the world on the H.M.S. Beagle, Darwin collected many crustaceans. When he returned, the collection was scattered and partly lost. But here is just one crab collected by Darwin himself, one of many from Oxford collection of Darwin’s crustaceans:

Darwin’s crab collection recently went on tour to Australia.

Crustaceans are mentioned in the Origin:

(E)ven the illustrious Cuvier did not perceive that a barnacle was, as it certainly is, a crustacean; but a glance at the larva shows this to be the case in an unmistakeable manner.

It is no accident to find reference to barnacles, since Darwin had some years earlier published major monographs on barnacles, a plate from which is the second Tuesday Crustie, which shows some of the larvae that showed that barnacles were crustaceans:

Description of the plate is here. For comparison, here’s a live one, taken from here:

Darwin spent years trying to sort out the barnacles. Jonathan Weiner argues in The Beak of The Finch barnacles forced Darwin to confront the problem of variation, and the difficulties of determining what is a species and what is merely a “variety.” And it was not an easy task, as indicated in the title of this post, which was taken from a letter Darwin wrote to W.D. Fox.

fMRI in the courtroom

From ScienceInsider:

fMRI scans of brain activity have been used as evidence in the sentencing phase of a murder trial.

I’m guessing we’re only a few years out from a trial that will rule on whether fMRI passes precedents for routine use in American courts.

Hat tip: mocost

Is it time to beg yet?

The nomination deadline for The Open Laboratory anthology, the annual compilation of the best science writing on blogs, has only one week to go. If there’s a post from this blog that you liked, please consider nominating it for the anthology. Posts from 1 December 2008 to 30 November 2009 are eligible.

Here are some suggestions, in roughly chronological order. If there are other posts you like, by all means, submit those.

• Muscle innervation is not a connectome
• Do male crickets shorten the lives of female crickets?
• Is the mimic octopus misnamed?
• Island girls: Why Hawaiian female crickets aren’t very choosy
• Jellyfish nervous system myth busted
• The small brain of the biggest fish in the world
• Fence lizards versus fire ants: Evolutionary fail?
• Evolution back and forth, from snakes to molecules
• Face it: Being a scientist can really suck
• The birth of dragons
• The princess and the perfume, a hermit crab fairy tale
• I want to be Carl Sagan, but can’t

Click here to submit an entry. A Blog Around the Clock regularly updates the list of entries; here’s a recent one (probably out of date by the time you read this).

In case you’re wondering why I don’t just nominate myself, because it feels gauche to nominate a bunch of your own stuff.

Dear students, about this coming holiday

Dear students,

I know that the university is closed on Thursday and Friday this week. I’m told it’s some kind of American holiday thing.

Should you happen to ask me if we are having classes on Wednesday, please forgive me if I reply with a little more sharpness in my voice than is really necessary. Please forgive me if I narrow my eyes, close them for a second, or even roll them.

You and I both know full well that the university is not closed on Wednesday. Wednesday is a regularly scheduled class day. It would be unprofessional of me not to have classes Wednesday. I’m sure you value learning (you paid to take this class with me, after all), and I would hate for you to feel you did not get full value for your dollar because I just canceled classes at random. On a whim. Because, you know, I just didn’t feel like coming in, or it would be inconvenient to me.

I know you don’t intend to impugn my professionalism, but that’s how it feels to me when you ask if I’m having class on a day the university is open. And because I have professional pride, I sometimes tend to overreact a little to questions like that.

Additional: See here.

Texas textbooks toast?

I’ve frequently had reason to talk about Texas science standards here, thanks to the dubious actions of the Texas State Board of Education. It’s often been noted by commentators around the nation is that because Texas is such a huge textbook market, textbook publishers make their books conform to the Texas standards. So when Texas adopts bad standards, the rest of the United States tends to feel the effects.

The Fort Worth Star-Telegram reports that the state is seriously considering moving to online materials, and it could be very quickly – maybe less than a year. The Texas Tribune has a longer article detailing the same subject.

I think this is probably good news in many ways (some of my thoughts on textbooks are here). People in other states will probably have less fear of bad decisions bleeding over into their jurisdictions.

That said, I am worried that this might reduce the spotlight on the Texas State Board of Education off the hook. Their decisions might be subjected to less scrutiny and criticism nationally, creating the possibility that they might do more damage, albeit to fewer people.

Who doesn’t love a good Venn diagram?

That said, this only covers the main science portion of the blog, not the various other concerns addressed here.

Taming the backchannel beast

Over at Speaking About Presenting, Olivia Mitchell has written a free ebook about working with Twitter and similar online tools during presentations. It’s a great snapshot of a fairly fast-moving aspect of presentations, and has many good, practical ideas. And it documents some of the harshtag horror shows that have been happening in the last few months.

Extinction through fornication

Normally, we think of extinction happening because organisms fail to reproduce. In the case of Canadian sticklebacks, some incipient species are going extinct because they are reproducing all too well.

Three-spined stickleback have many populations around the world. The main population lives in marine systems most of their lives. But over and over, small pockets of animals have been caught in freshwater lakes, and started to go off on their own evolutionary trajectory, separating from their marine ancestors.

Within the individual lakes, the sticklebacks can continue to branch off further from each other. Some specialize in lake bottoms; some on the surfaces. In my old stomping grounds of Vancouver Island, this has been going on in Enos Lake. Back in the early 1990s, the bottom- and surface dwellers were said to be separate species, as they were very morphologically distinct and didn’t interbreed with each other. That said, they were never formally described as separate species and given new species names, as far as I can tell.

This may turn out to be a good thing, because when Behm and colleagues sampled the stickleback populations in 2005, the two distinct groups were gone. To be clear, there were still stickleback – but instead of two clearly distinct clusters with no interbreeding, there was one cluster with lots of interbreeding.

Previously, the two different body shapes had different diets, as measured both by direct observation of the prey types in stomach, and by carbon isotopes found in the fish. You’ll forgive me, I hope, if I skip the details of how lake food webs influence the ration of different carbon types the fish ingest. In any case, that difference between body shape and food type had also vanished.

It’s possible that there are a lot of intermediate shaped fish, but maybe they’re not doing so well. Turns out that as of right now, there’s no evidence of that. The intermediates don’t seem to be small, seem to be growing fine, and so on.

All of this raises the question: What the heck has suddenly caused these two distinct groups to start merging back together?

The authors’ surprising suggestion is that it’s because of crayfish. Signal crayfish (Pacifastacus leniusculus) were introduced into Enos Lake around 1990. Behm and company don’t have a clear reason why having crayfish in the lake should have this dramatic impact on the stickleback populations, but the timing of the two events is mighty suspicious. There’s clearly some interesting ecology to track down in this system.

In the last few decades, we’ve really come to appreciate how dynamic and quick evolutionary processes, like speciation, can be. This research shows that speciation, at least in the early stages, can also be a fairly fragile thing, easily falling apart for reasons that are not entirely clear at first glance.

Reference

Behm, J., Ives, A., & Boughman, J. (2009). Breakdown in Postmating Isolation and the Collapse of a Species Pair through Hybridization The American Naturalist DOI: 10.1086/648559

Stickleback picture by user SuperIDR on Flickr, and used under a Creative Commons license.

Overqualified

Sincere question, not rhetorical.

How and when and, for goodness’ sake, why did “overqualified” become a reason to turn someone away from employment?

This is starting to bother me a lot. I mean, I help run a Masters program, and am advisor on a major grant to create graduate opportunities for Hispanics, am the lead on one undergraduate research program and participate in another.

But I have my doubts. Reading things like this or this... don’t help.

The concept of “overqualified” just gnaws away at the whole reason for those programs. Not just ours, but nationally. Internationally.

How are you going to create a technically skilled work force in a society when there’s a threat that that very training can be held against them?

I understand that when there are too many applications too read, you’ve got to cut something somewhere. But it seems to me that, “Oh, they’ll just leave when the economy is better” is short-sighted. This is a fantastic opportunity to get amazingly smart people in your company. Imagine the energy and talent a hiring business could recruit today if it said, “nobody is overqualified.” Even if they do leave, you’ll probably have a better company at the end than when you started.

Somehow, I can’t help but think that what’s really leading to the concept of “overqualified” is that an employer doesn’t want an employee smarter than they are. Too likely to upset delicate workplace power relationships. Or something.

I clearly don’t get it.

The Zen of Presentations, Part 29: The shirt on your back

Steve Jobs is good at presentations. Garr Reynolds has written about this a lot over on his Presentation Zen blog. Now, a whole new book has been written about him. This slideshow says:

Steve Jobs can wear a black mock turtleneck, blue jeans, and running shoes because, quite simply, he has earned the right to dress anyway he wants. For most communicators, it’s best to dress a little better than everyone in your audience.

I can’t help but find the rationalization funny. Author Carmine Gallo spends the book looking at what makes one person a great speaker, but shies away from the possibility that maybe he is great partly because of how he dresses, not in spite of how he dresses.

Maybe people are responding to seeing someone they can relate to. Maybe people are responding to someone who is not relying on artifice. Maybe people are responding to seeing someone who is genuine.

Audiences crave authenticity. It’s a driver behind the success of so-called “reality” shows or YouTube videos: people are looking for the unscripted, the immediate.

With too many presenters, you can tell their dress for their presentation is an act. A total put on. A sham. It’s not real, it’s not who they are, and they’re not comfortable.

Soon after, I spotted this post by Kathy Reiffenstein on what to wear during a presentation. This also struck me as greatly over-stressing formality and business wear, but I appreciated Chris Atherton’s response to it:

Love how much of this is really about attention (yours and audience's).

Right. Be worried not so much about how you look as whether that look will distract you or the audience.

I spelled out my own take over on dressing for presentations on Better Posters.

Tuesday Crustie: Termite of the sea

 

This squat lobster, Munida andamanica, has been in the news recently for its peculiar ability to eat wood. Picture from here.

Additional:  For more on the science behind the discovery of this animal’s diet, see this post on Deep-Sea News.

For your consideration

I am not too proud to beg.

The nomination deadline for The Open Laboratory anthology, the annual compilation of the best science writing on blogs, is in two weeks. If there’s a post from this blog that you liked, please consider nominating it for the anthology. Posts from 1 December 2008 to 30 November 2009 are eligible.

Here are some suggestions, in roughly chronological order. If there are other posts you like, by all means, submit those.

• Muscle innervation is not a connectome
• Do male crickets shorten the lives of female crickets?
• Vestigial icons
• I’m trying here
• Explanation and evangelism
• Science publishers are agents
• Is the mimic octopus misnamed?
• Island girls: Why Hawaiian female crickets aren’t very choosy
• Jellyfish nervous system myth busted
• Truth for the hard of thinking
• The small brain of the biggest fish in the world
• Fence lizards versus fire ants: Evolutionary fail?
• Evolution back and forth, from snakes to molecules
• Face it: Being a scientist can really suck
• The birth of dragons
• The princess and the perfume, a hermit crab fairy tale
• I want to be Carl Sagan, but can’t

Click here to submit an entry. A Blog Around the Clock regularly updates the list of entries; here’s a recent one (probably out of date by the time you read this).

In case you’re wondering why I don’t just nominate myself, I think it’s better for readers to decide what’s good than writers. And because it feels gauche to nominate a bunch of your own stuff.