Brain and Behavior
clock | August 16, 2006The 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…
ddobbs | August 15, 2006Among the many wonders of neuroscience -- and central to the discipline -- is the brain's plasticity, its ability to rework synapses and networks to respond to new challenges and experiences. In this dynamic lies the physical explanation of the fluid nature of experience, thought, and consciousness. This is why I find so fascinating the work of those who proposed and discovered the mechanisms underlying this plasticity, such as Ramon y Cajal, Donald Hebb, and Eric Kandel. These and other researchers showed the fundamentals of how changing synapses allow our brains to learn new lessons and…
clock | August 15, 2006
One of the assumptions in the study of circadian organization is that, at the level of molecules and cells, all vertebrate (and perhaps all animal) clocks work in roughly the same way. The diversity of circadian properties is understood to be a higher-level property of interacting multicelular and multi-organ circadian systems: how the clocks receive environmental information, how the multiple pacemakers communicate and synchronize with each other, how they convey the temporal information to the peripheral clocks in all the other cells in the body, and how perpheral clocks generate…
clock | August 15, 2006
One of the important questions in the study of circadian organization is the way multiple clocks in the body communicate with each other in order to produce unified rhythmic output.
In the case of mammals, the two pacemakers are the left and the right suprachiasmatic nucleus (SCN). The tow nuclei are anatomically close to each other and have direct nerve connections between them, so it is not difficult to imagine how the two clocks manage to remain continuously coupled (syncronized) to each other and, together, produce a single output, thus synchronizing all the rhythms in the body.
In the…
clock | August 14, 2006Going 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 | August 14, 2006
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)…
drorzel | August 13, 2006Well, it's as good a guess at a collective noun for "kerfuffle" as any other...
There have been three moderately heated bloggy controversies that I've been following over the past week, that I haven't commented on. Mostly because I don't really have that much to add to any of the arguments, or at least, not enough to merit a blog post.
I do want to note their existence, though, and maybe by combining them together, it won't feel so much like a pointless fluff post. So if you're dying to know my opinions on the crimes of fanfic, Oliver Stone's casting decisions, or Hooters, click on through to…
retrospectacle | August 10, 2006"New Zealand's indigenous Maori population reacted angrily on Wednesday to a researcher's findings that Maori have a high representation of a gene linked to aggression, as the nation faces a domestic violence crisis."
According to a Yahoo news story, genetic epidemiologist Rod Lea recently presented research in Australia that Maori men were twice as likely to carry monoamine oxidase than European men, describing it as "the warrior gene." This gene has apparently been tied to aggression and risk-taking behaviors such as smoking and gambling.
"I believe this gene has an influence on behavior of…
purepedantry | August 7, 2006The traditional Darwinian view of evolution holds that evolution occurs through the selection of the most successful members of a group. Each member of the group is stable over its lifetime. This view was later modified to include the idea that DNA is the stable carrier of this information throughout the lifetime of an organism. But cells do hold other forms of genetic information or so-called epigenetic modifications -- that generally take the form of modifications to DNA such as methylation which influence their transcription. There is some evidence that these modifications are…
purepedantry | August 7, 2006I was at a wedding this weekend, and I was getting in one of those conversations that drunk people get into at weddings: what are the gender differences in cognition?
OK, so maybe you don't get into conversations like this with people you don't know well, but I do.
Anyway, it got me thinking that I should post a summary of what is known. Much has been argued about the relevance of differences in cognition. Larry Summers lost his job over it. Ben Barres wrote a lovely editorial about it -- that we all talked about at length (my stuff is here, here, and here). The Economist has an…
clock | August 7, 2006A short post from April 17, 2005 that is a good starting reference for more detailed posts covering recent research in clock genetics (click on spider-clock icon to see the original).
As I have mentioned before, there was quite an angst in the field of chronobiology around 1960s about the lack of undestanding of circadian and other rhythms at cellular and subcellular levels. Experiment involved manipulation of the environment (e.g,. light cycles) and observing outputs (e.g., wheel-running rhythms), while treating the clock, even if its anatomical location was known, as a "black box".…
j7uy5 | August 5, 2006About 15 years ago, I was giving a lecture on psychiatric medication to
a group of MSW
students. One student asked a question that was intended to
be
provocative. She asked, "how can you justify giving
medication to
treat a problem that is obviously psychological in origin, like
posttraumatic stress disorder?"
What she was referring to, was a paradigm that was commonly held at the
time. Specifically, there was this notion that some problems
were
psychological, and others were biological, in origin. It was
thought, by some, that there was a clear distinction between the two
kinds of…
j7uy5 | August 2, 2006I just finished reading a news release pertaining to a finding in
psychiatric genetics. I was prepared to be irritated, but was
pleased instead.
href="http://www.med.umich.edu/opm/newspage/2006/ocd.htm">New
genetic findings add to understanding of obsessive-compulsive disorderKara Gavin
July 26, 2006
ANN ARBOR, MI – Obsessive-compulsive disorder tends to
run in families, causing members of several generations to experience
severe anxiety and disturbing thoughts that they ease by repeating
certain behaviors. In fact, close relatives of people with
rel="tag"
href="http://www.med.umich.…
oracknows | August 2, 2006I had seriously considered jumping all over this story when I first saw it early Monday morning. After all, look at the headline:
Jewish groups call for hate-crime probe on Mel Gibson
A more truly ominous thing to be calling for based on a drunken anti-Semitic tirade I have a hard time imagining. As you may remember from my previous discussions of, for example, the David Irving trial, I am very much against hate speech laws. What I don't recall if I've ever mentioned before is that I'm also very skeptical of hate crime laws. I can see using racial or religious bigotry as an aggravating…
loom | August 1, 2006Once again, I hear the siren song of Toxoplasma, the parasite that dwells in the brains of 50 million Americans.
Toxoplasma gondii is an extraordinary creature, whose exploits I've chronicled in previous posts , an article in the New York Times and my book Parasite Rex. This single-celled organism has a life cycle that takes it from cats to other mammals and birds and back to cats again. Studies have shown that the parasite can alter the behavior of rats, robbing them of their normal fear of cats--and presumably making it easier for the parasites to get into their next host.
Toxoplasma is…
clock | August 1, 2006It's been a while since I've written anything about one of my pet topics - the way the changes in the society are resulting in the change in attitudes towards sex and gender, and the change in the institution of marriage, and how it all relates to politics of the moment.
I've been playing it pretty carefully since my move here to SEED scienceblogs, not firing away with my biggest artillery yet. I want to get back there again, gradually, so this is going to be just a summary and an opportunity to get you to read some of my older stuff to see where I stand. It is a also a test balloon to see…
clock | July 31, 2006It has been known for decades that scheduled meals can entrain the circadian clock. In some species (e.g., in some birds), regular timing of feeding entrains the main circadian system of the body in the suprachiasmatic (SCN) area of the hypothalamus, the retina and the pineal. In other species (e.g., rodents), it appears that the food-entrainable oscillator is anatomically and functionally distinct from the main pacemaker in the SCN.
Researchers working on different species discovered different properties and different anatomical locations for the food-entrainable clock. Now, a study…
clock | July 31, 2006 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…
neurontic | July 30, 2006 While we're on the subject of brain size, I wanted to share another interesting Temple Grandin theory. In Animals in Translation, Grandin suggests that we humans may be suffering from a species superiority complex. While she agrees that domestication was responsible for a 10 percent reduction in brain size in dogs, she contends that the civilizing process cut both ways. Taming wolves had a profound effect on the evolution of the human brain, according to Grandin.
Recent scientific findings suggest that human-wolf cohabitation began as long as 100,000 years ago. If these findings are correct…
cortex | July 29, 2006Well, sort of. A well-timed insult by Materazzi also helped. But the WSJ reports today that several members of the Italian team used neurofeedback earlier this year to help hone their powers of concentration:
In February, months before the tournament started, some of Italy's best soccer players, including a handful who would later play in the Cup, began spending much of their practice time in a small room in Milan furnished with six luxury leather recliners facing a glass wall.
On the other side of the glass Bruno De Michelis, head of the sports science lab for AC Milan, one of the country's…