Brain and Behavior
clock | July 16, 2009This post (click on the icon) was originally written on May 07, 2005, introducing the topic of neuroendocrine control of seasonal changes in physiology and behavior.
So far, I have directed all my attention to daily - circadian - rhythms, and pretty much ignored other rhythms that correspond to other cycles in nature. Another obvious cycle in nature is the procession of seasons during a year.
Just as an environment during the day is different from the same environment during the night and thus requires different adaptations for survival, so the winter environment and the summer environment…
razib | July 13, 2009Update: See Ed Yong.
Randall Parker points me to a new paper from Joshua Greene which describes the neurological responses of individuals when do, or don't, lie, when lying might be in their self-interest. From EurekaAlert:
The research was designed to test two theories about the nature of honesty - the "Will" theory, in which honesty results from the active resistance of temptation, and the "Grace" theory in which honesty is a product of lack of temptation. The results of this study suggest that the "Grace" theory is true, because the honest participants did not show any additional neural…
clock | July 12, 2009The third post in the series on entrainment, first written on April 10, 2005, starts slowly to get into the meat of things...As always, clicking on the spider-clock icon will take you to the site of the original post.
In the previous post, I introduced the concept of entrainment of circadian rhythms to environmental cycles. As I stated there, I will focus on non-parametric effects of light (i.e., the timing of onsets and offsets of light) on the phase and period of the clock.
Entrainment is a mechanism that forces the internal period (&tau - tau) of the biological clock to assume the…
oracknows | July 10, 2009While I'm away communing with fellow skeptics at TAM7, I'm reposting some classic insolence from the month of July in years past. For today, there was really no other choice for what bit of Classic Insolence to repost, except that, today, there's no insolence whatsoever. The reason is that today is a very sad day. It is the one year anniversary of the death of our beloved dog Echo. In 2008, about about three weeks before the day for which this is the one year anniversary, we noticed that Echo was favoring her hind leg. When I looked her over, I noticed a lump, which, thanks to the power of…
clock | July 10, 2009
A January 20, 2006 post placing a cool physiological/behavioral study into an evolutionary context.
There are two main hypotheses - not mutually exclusive - for the adaptive value of having a circadian clock. One is the Internal Synchronization hypothesis, stating that the circadian clock serves to synchronize biochemical and physiological processes within the body. The second is the External Synchronization hypothesis, stating that the circadian clock serves to syncronize the physiology and behavior to the natural environment.
The prediction from the Internal Hypothesis is that circadian…
neurophilosophy | July 10, 2009IN the 1860s, the French physician Paul Broca treated two patients who had lost the ability to speak after suffering strokes. When they died, he examined their brains, and noticed that both had damage to the same region of the left frontal lobe. About a decade later, neuropsychiatrist Carl Wernicke described a stroke patient who was unable to understand written words or what was said to him, and later found in this patient's brain a lesion towards the back of the left temporal lobe.
Thus was established the classical neurological model, in which language is localized to two specific areas…
emjohnson | July 10, 2009
The "Revelation" as described by St. John, though likely inspired through the
use of hallucinogens (see The Mystery of Manna).
The title for this post comes from a terrific book by the neuroscientist Antonio Damasio, but I think it's appropriate for a discussion on faith, feeling and reason. Francis Collins' nomination as Director of the National Institutes of Health has effectively gotten people talking about religion, science and what, if anything, each should have to do with the other. I recently brought up Sam Harris' critique of the editor's at Nature for their praise of Collins' book…
cortex | July 10, 2009Over at The Big Money, Mark Gimein has a fascinating article on Swoopo.com. Gimein calls Swoopo "the crack cocaine of auction sites" and says it's "the evil bastard child of game theory and behavioral economics." The site works like this:
Consider the MacBook Pro that Swoopo sold on Sunday for that $35.86. Swoopo lists its suggested retail price at $1,799; judging by the specs, you can actually get a similar one online from Apple (AAPL) for $1,349, but let's not quibble. Either way, it's a heck of a discount. But now look at what the bidding fee does. For each "bid" the price of the computer…
clock | July 10, 2009Going into more and more detail, here is a February 11, 2005 post about the current knowledge about the circadian organization in my favourite animal - the Japanese quail.
Japanese quail (Coturnix coturnix japonica), also known as the Asian Migratory Quail, are gallinaceous birds from the family Phasianidae, until 1960s thought to be a subspecies of European migratory quail (Coturnix coturnix coturnix), but now considered to be a separate species, designated as Coturnix japonica. The breeding range of the wild population encompasses Siberia, Mongolia, northeastern China and Japan, while the…
clock | July 9, 2009This is an appropriate time of year for this post (February 05, 2006)...
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So, why do I say that it is not surprising the exposure to bright light alleviates both seasonal depression and other kinds of depression, and that different mechanisms may be involved?
In mammals, apart from visual photoreception (that is, image formation), there is also non-visual photoreception. The receptors of the former are the rods and cones that you all learned about in middle school. The receptors for the latter are a couple of thousand Retinal Ganglion…
clock | July 9, 2009 This post was originally written on February 11, 2005. Moving from relatively simple mammalian model to more complex systems.
I have previously described the basic properties of the circadian organization in mammals. Non-mammalian vertebrates (fish, amphibians, reptiles and birds) have more complex circadian systems than mammals. While the suprachiasmatic area remains a site of circadian pacemakers, it is, unlike in mammals, not the only such site.
The pineal organ, which in mammals is a purely secretory organ, is directly photosensitive in other vertebrates (with the exception of snakes)…
clock | July 7, 2009
If you really read this blog 'for the articles', you know some of my recurrent themes, e.g., that almost every biological function exhibits cycles and that almost every cell in every organism contains a more-or-less functioning clock. Here is a new paper that combines both of those themes very nicely, but I'll start with a little bit of background first.
Daily Rhythms in Sensory Sensitivity
If almost every biochemical, physiological and behavioral function exhibits daily cycles, it is no surprise that such rhythms have been discovered in sensory sensitivity of many sensory modalities -…
ddobbs | July 7, 2009Scientific American has a good story by Edmund S. Higgins suggesting that might be the case. As the story notes, the evidence for such a toll is still preliminary. But the story's opening, which tells of a parent seemingly overeager to medicate a child who didn't need it, gives an idea of why the question is more important than we might like.:
At the time of this visit, the boy was off the medication, and I conducted a series of cognitive and behavioral tests on him. He performed wonderfully. I also noticed that off the medication he was friendly and playful. On a previous casual encounter,…
emjohnson | July 6, 2009Scientia Pro Publica #7 is now up at Greg Laden's Blog. This is the crème brûlée of science carnivals and includes the best writing from the past two months. Greg was kind enough to include my recent post The Struggle for Coexistence. There are some excellent posts in this edition, so click on over and check them out. Some of the ones I found particularly interesting in this edition include:
A Primate of Modern Aspect looks at the evolution of a malaria resistance gene in wild primates, a paper co-authored by my former professor Susan Alberts:
This is an important step forward in the…
clock | July 5, 2009 I wrote this post back on January 23, 2005. It explains how clock biologists think and how they design their experiments:
So, are you ready to do chronobiological research? If so, here are some of the tips - the thought process that goes into starting one's research in chronobiology.
First, you need to pick a question. Are you interested in doing science out of sheer curiosity to discover stuff that nobody knew before (a very noble, but hard-to-fund pursuit)? Or would you prefer your work to be applicable to human medicine or health policy, veterinary medicine, conservation biology, or…
clock | July 4, 2009Just trying to catch up with the publicartions in various PLoS Journals this past week. Here are some interesting titles.
As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Mendeley, Connotea, Stumbleupon, Facebook and Digg) with just one click. Here are my own picks for the week - you go and look for your own favourites:
What a Plant Sounds Like: The Statistics of Vegetation Echoes as Received by Echolocating Bats:
More than 800 species of bats…
clock | June 30, 2009
This is the second in the series of posts designed to provide the basics of the field of Chronobiology. See the first part: ClockTutorial #1 - What Is Chronobiology and check out the rest of them here - they will all, over time, get moved to this blog.
Here is a brief overview of the concepts and terms used in the field of chronobiology. I will write much more detailed accounts of various aspects of it in the future.
Seasons of the year, phases of the moon, high and low tides, and alternation between night and day are examples of cyclic changes in the environment. Each presents a different…
clock | June 29, 2009Considering I've been writing textbook-like tutorials on chronobiology for quite a while now, trying always to write as simply and clearly as possible, and even wrote a Basic Concepts And Terms post, I am surprised that I never actually defined the term "biological clock" itself before, despite using it all the time.
Since the science bloggers started writing the 'basic concepts and terms' posts recently, I've been thinking about the best way to define 'biological clock' and it is not easy! Let me try, under the fold:
A biological clock is a structure that times regular re-occurence of…
palmd | June 28, 2009(NB: as is usual with my more "science-y" posts, oversimplification is the rule. --PalMD)
It's been a very long while since I've updated my series on cancer. I keep meaning to, but you know how things go. Lately, though, I've been curious about radiation oncology, the use of ionizing radiation to treat cancers. What set me off was a recent Times article about some pretty crappy practices. Radiation oncology requires a very thorough education in physics and medicine and the field attracts some of the best minds, but no field is immune to unethical behavior (which in this case I feel is…
pharyngula | June 26, 2009Yesterday morning, I was in a discussion on UK Christian talk radio on the topic of "Is Christian faith at odds with science?", with Denis Alexander of the Faraday Institute for Science and Religion. It's going to be available as a podcast at sometime in the next day, but I may not be able to link to it right away — tomorrow I fly away to Germany for a week, so my schedule is going to be a bit chaotic for a while.
Don't expect fireworks. It was the usual feeble accommodationist claptrap, but I had my nice man hat on and actually tried to get across some basic ideas. To no avail, of course,…