Category Archives: Neuroscience

Encephalon #82

Welcome to the 81st 82nd edition of Encephalon, neuroscience blog carnival that keeps dying and getting resurrected over and over again. Let’s hope it keeps going for a long time again, as it collects some of the best writing about the brain, mind and behavior on science blogs. Including this month’s edition – a great collection of entries, if I may say so myself! Without further ado, instead of wasting your time on long introductions, I will let you dig in and enjoy:

Let’s start with Stress: Does Gender Matter? by Allison Goldstein from The Wiley Life Sciences Blog.

Taylor Burns of Student Voices wrote If You’re Reading This, You’re Probably Weird.

Mo Costandi at Neurophilosophy penned this delicious post: Neurocriminology in prohibition-era New York

Mark Robinson emerged from the Somatosphere to contribute The Privatization of Neuroscience: The University, The State and the Moral Aims of Science.

Zen Faulkes of NeuroDojo sent in three posts this month: It’s nothing personal, it’s just that my brain is bigger than yours and Are big brains better for long trips in bats? and Neither me nor thee: the fish in the mirror

Janet Kwasniak has thoughts on thoughts including thoughts on A step towards correlates of consciousness.

The Neurocritic of the eponymous The Neurocritic is neurocritical: Seizures Triggered by Strawberry Syrup.

Sandeep Gautam who has fallen into The Mouse Trap sent out a message – Personality and Motivation looks at a paper linking Big Five personality traits (FFM) with their underlying motivational reaction norms.

Dr.Romeo Vitelli of Providentia contributes two posts: The Opium Eater on one of the first “psychenauts” and a literary giant, to boot, and Born to be Wild – One of the more recent genetics= violence controversies to be hashed out in the media.

LivingwithN24 from DSPS, a sleep disorder is doing some self-study in Charting the course of N24.

Jesse Bering of Bering in Mind walked accros the Bering Straight to ask us: Not so fast… What’s so premature about premature ejaculation?

From Vaughan Bell of Mind Hacks comes It only exists if I can see colours on a brain scan. My brain must have lit up when I was reading that post…or otherwise it does not exist!

Maria Schamis Turner of The Brain Detectives was not asleep when she wrote Homicidal somnambulism.

Allison Brager of Dormivigilia wrote What the Airlines Neglect to Tell You: Jet Lag Elicitation of a Proinflammatory Response, which is only applicable if you managed to pass through the TSA security checkpoint in the first place.

Neuroskeptic is skeptical – The Limits of Neuroplasticity.


Jeremy Dean of PsyBlog has a whole series of posts on persuasion, includin Caffeine Makes Us Easier to Persuade.

Virginia Hughes over at SFari blog wonders about Negative feedback – Can your brain be trained to make better brain waves?

Christian Jarrett at the BPS Research Digest Blog is asking: Moving the eyes but not looking – why do we do it?

Princess Ojiaku from Science with Moxie has a two-parter: The Genes of a Rocker and AVPR1A: Music in your Genes?

I picked two Scicurious posts from Neurotic Physiology, one serious, one…also serious: Friday Weird Science: Does Your Aunt Only Visit at the Dark of the Moon? and New Possibilities for Depression: A MAP Kinase regulator.

Eric Michael Johnson who usually blogs at The Primate Diaries wrote a guest-post on the Guest Blog at Scientific American – A primatologist discovers the social factors responsible for maternal infanticide

And we’ll finish with Jason Goldman of The Thoughtful Animal and Social Cognition in a Non-Social Reptile? Gaze-Following in Red-Footed Tortoises.

And this is it for this month. If I missed your entry, let me know ASAP.

Next month, the carnival will be hosted by Dr. Romeo Vitelli at Providentia. Watch the Encephalon homepage for updates and instructions.

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Encephalon, the neuroscience blog carnival, is coming back!

Yes, it has risen again!

You can still find the old archives from the first run in 2006/2007 here (click on “past carnivals” tab), and the second run in 2008/2009 here, but the new archives will be built fresh, starting this month, with Encephalon #81 on Cephalove.

I will host the next one, #82, on November 29th 2010. Send your entries by midnight before that date to: Coturnix AT gmail DOT com

Evolutionary and Developmental Precursors for the Human Mathematical Mind

Now that summer is starting to fade, here is something else to look forward to: The 2010-2011 American Scientist Pizza Lunch speaker series returns next month.

Join us at noon, Tuesday, Sept. 21 here at Sigma Xi to hear Duke University cognitive psychologist Elizabeth Brannon give a talk entitled: “Evolutionary and Developmental Precursors for the Human Mathematical Mind.” In other words, Brannon studies what we all take for granted: our ability to do the numbers. She does it, in part, with studies of human babies and other primates.

Thanks to a grant from the N.C. Biotechnology Center, American Scientist Pizza Lunch is free and open to science journalists and science communicators of all stripes. Feel free to forward this message to anyone who might want to attend. RSVPs are required (for the slice count) to cclabby@amsci.org

Directions to Sigma Xi, the Scientific Research Society in RTP, are here: http://www.sigmaxi.org/about/center/directions.shtml

Seven Questions….with Yours Truly

Last week, my SciBling Jason Goldman interviewed me for his blog. The questions were not so much about blogging, journalism, Open Access and PLoS (except a little bit at the end) but more about science – how I got into it, what are my grad school experiences, what I think about doing research on animals, and such stuff. Jason posted the interview here, on his blog, on Friday, and he also let me repost it here on my blog as well, under the fold:

Continue reading

Are Zombies nocturnal?

day of the dead.jpgBlame ‘Night of the Living Dead’ for this, but many people mistakenly think that zombies are nocturnal, going around their business of walking around town with stilted gaits, looking for people whose brains they can eat, only at night.
You think you are safe during the day? You are dangerously wrong!
Zombies are on the prowl at all times of day and night! They are not nocturnal, they are arrhythmic! And insomniac. They never sleep!
Remember how one becomes a zombie in the first place? Through death, or Intercision, or, since this is a science blog and we need to explain this scientifically, through the effects of tetrodotoxin. In any case, the process incurs some permanent brain damage.
One of the brain centers that is thus permanently damaged is the circadian clock. But importantly, it is not just not ticking any more, it is in a permanent “day” state. What does that mean practically?
When the clock is in its “day” phase, it is very difficult to fall asleep. Thus insomnia.
When the clock is in its “day” phase, metabolism is high (higher than at night), thus zombies require a lot of energy all the time and quickly burn through all of it. Thus constant hunger for high-calory foods, like brains.
Insomnia, in turn, affects some hormones, like ghrelin and leptin, which control appetite. If you have a sleepless night or chronic insomnia, you also tend to eat more at night.
But at night the digestive function is high. As zombies’ clock is in the day state, their digestion is not as efficient. They have huge appetite, they eat a lot, but they do not digest it well, and what they digest they immediately burn. Which explains why they tend not to get fat, while living humans with insomnia do.
Finally, they have problems with wounds, you may have noticed. Healing of wounds requires growth hormone. But growth hormone is secreted only during sleep (actually, during slow sleep phases) and is likewise affected by ghrelin.
In short, a lot of the zombies’ physiology and behavior can be traced back to their loss of circadian function and having their clock being in a permanent “day” state.
But the real take-home message of this is…. don’t let your guard down during the day!
sbzombies_blogaroundtheclock.png
Picture of me as a Zombie (as well as of all my Sciblings – go around the blogs today to see them) drawn by Joseph Hewitt of Ataraxia Theatre whose latest project, GearHead RPG, is a sci-fi rogue-like game with giant robots and a random story generator – check it out.

Revenge of the Zombifying Wasp (repost)

Revenge of the Zombifying WaspAs this is a Zombie Day on scienceblogs.com, here is a re-post of one of my old post about one of the coolest parasites ever (from February 04, 2006):
a1%20ampulex_compressa.jpgI am quite surprised that Carl Zimmer, in research for his book Parasite Rex, did not encounter the fascinating case of the Ampulex compressa (Emerald Cockroach Wasp) and its prey/host the American Cockroach (Periplaneta americana, see also comments on Aetiology and Ocellated).
In 1999, I went to Oxford, UK, to the inaugural Gordon Conference in Neuroethology and one of the many exciting speakers I was looking forward to seeing was Fred Libersat. The talk was half-hot half-cold. To be precise, the first half was hot and the second half was not.
In the first half, he not just introduced the whole behavior, he also showed us a longish movie, showing in high magnification and high resolution all steps of this complex behavior (you can see a cool picture of the wasp’s head here).
a2%20wasp-cockroach.jpgFirst, the wasp gives the roach a quick hit-and-run stab with its stinger into the body (thorax) and flies away. After a while, the roach starts grooming itself furiously for some time, followed by complete stillness. Once the roach becomes still, the wasp comes back, positions itself quite carefully on top of the raoch and injects its venom very precisely into the subesophageal ganglion in the head of the roach. The venom is a cocktail of dopamine and protein toxins so the effect is behavioral modification instead of paralysis.
Apparently, the wasp’s stinger has receptors that guide it to its precise target:

“To investigate what guides the sting, Ram Gal and Frederic Libersat of Ben-Gurion University in Beer-Sheva, Israel, first introduced the wasp to roaches whose brains had been removed. Normally, it takes about a minute for the wasp to find its target, sting, and fly off. But in the brainless roaches, the wasps searched the empty head cavity for an average of 10 minutes. A radioactive tracer injected into the wasps revealed that when they finally did sting, they used about 1/6 the usual amount of venom. The wasps knew something was amiss.”

The wasp then saws off the tips of the roach’s antennae and drinks the hemolymph from them. It builds a nest – just a little funnel made of soil and pebbles and leads the roach, by pulling at its anteanna as if it was a dog-leash, into the funnel. It then lays an egg onto the leg of the roach, closes off the antrance to the funnel with a rock and leaves. The roach remains alive, but completely still in the nest for quite some time (around five weeks). The venom, apart from eliminating all defence behaviors of the roach, also slows the metabolism of the cockroach, allowing it to live longer without food and water. After a while, the wasp egg hatches, eats its way into the body of the roach, eats the internal organs of the roach, then pupates and hatches. What comes out of the (now dead) cockroach is not a larva (as usually happens with insect parasitoids) but an adult wasp, ready to mate and deposit eggs on new cockroaches.
Why was the second half of the talk a disappointment? I know for a fact I was not the only one there who expected a deeper look into evolutionary aspects of this highly complex set of behaviors. However, the talk went into a different direction – interesting in itself, for sure, but not as much as an evolutionary story would have been. Libersat described in nitty-gritty detail experiments that uncovered, one by one, secrets of the neuroanatomy, neurophysiology and neurochemistry of the cockroach escape behavior – the one supressed by toxin – as well as the chemistry of the toxin cocktail. Ganglion after ganglion, neuron after neuron, neurotransmitter after neurotransmitter, the whole behavior was charted for us on the screen. An impressive feat, but disappointing when we were all salivating at a prospect of a cool evolutionary story.
He did not say, for instance, what is the geographic overlap between the two species. I had to look it up myself afterwards. American cockroach can be found pretty much everywhere in the world. The wasp also has a broad geographical range from Africa to New Caledonia (located almost directly between Australia and Fiji) and, since 1941, Hawaii (another example of a non-native species wreacking havoc on the islands), but not everywhere in the world, especially not outside the tropics – there are most definitely parts of the planet where there are roaches but no Ampulex compressa.
In most cases in which one species is suspectible to the venom or toxin of another species, the populations which share the geography are also engaged in an evolutionary arms-race. The victim of the venom evolves both behavioral defenses against the attack of the other species and biochemical resistance to the venom. In turn, the venom evolves to be more and more potent and the animal more and more sneaky or camouflaged or fast in order to bypass behavioral defenses.
There are many examples of such evolutionary arms-races in which one of the species is venomous/toxic and the other one evolves resistance. For instance, garter snakes on the West Coast like to eat rough-side newts. But these newts secrete tetrodotoxin in their skins. The predator is not venomous, but it has to deal with dangerous prey. Thus, in sympatry (in places where the two species co-exist) snakes have evolved a different version of a sodium channel. This version makes the channel less susceptible to tetrodotoxin, but there is a downside – the snake is slower and more lethargic overall. In the same region, the salamanders appear to be evolving ever more potent skin toxin coctails.
Similar examples are those of desert ground squirrels and rattlesnakes (both behavioral and biochemical innovations in squirrels), desert mice (Southwest USA) and scorpions (again it is the prey which is venomous), and honeybees and Death’s-Head sphinx-moths (moths come into the hives and steal honey and get stung by bees after a while).
But Libersat never wondered if cockroaches in sympatry with Emerald wasps evolved any type of resistance, either behavioral or physiological. Perhaps the overwhelming number of roaches in comparison with the wasps makes any selective pressure too weak for evolution of defenses. But that needs to be tested. He also never stated if the attack by the wasp happens during the day or during the night. Roaches are nocturnal and shy away from light. The movie he showed was from the lab under full illumination. Is it more difficult for the wasp to find and attack the roach at night? Is it more difficult for the roach to run away or defend itself during the day? Those questions need to be asked.
Another piece of information that is missing is a survey of parasitizing behaviors of species of wasps most closely related to Ampulex compressa. Can we identify, or at least speculate about, the steps in the evolution of this complex set of behaviors (and the venom itself)? What is the precursor of this behavior: laying eggs on found roach carcasses, killing roaches before laying eggs on their carcasses, laying eggs on other hosts? We do not know. I hope someone is working on those questions as we speak and will soon surprise us with a publication.
But let me finish with a witty comment on Zimmer’s blog, by a commenter who, for this occasion, identified as “Kafka”:

“I had a dream that I was a cockroach, and that wasp Ann Coulter stuck me with her stinger, zombified my brain, led me by pulling my antenna into her nest at Fox News, and laid her Neocon eggs on me. Soon a fresh baby College Republican hatched out, burrowed into my body, and devoured me from the inside. Ann Coulter’s designs may be intelligent, but she’s one cruel god.”

Update: That post on The Loom attracted tons of comments. Unfortunately, most of them had nothing to do with the cockroaches and wasps – Carl’s blog, naturally, attracts a lot of Creationists so much of the thread is a debate over IDC. However, Carl is happy to report that a grad student who actually worked on this wasp/cockroach pair, appeared in the thread and left a comment that, among else, answers several of the behavioral and evolutionary questions that I asked in this post.
Update 2: You can watch some movies linked here and here.

The Primal Power of Play (video)