As reported in a paper published online today in the journal Nature, Caltech biologist David J. Anderson and his colleagues have genetically identified neurons that control aggressive behavior in the mouse hypothalamus, a structure that lies deep in the brain (orange circle in the image). Researchers have long known that innate social behaviors like mating and aggression are closely related, but the specific neurons in the brain that control these behaviors had not been identified until now.
The interdisciplinary team of graduate students and postdocs, led by Caltech senior research fellow Hyosang Lee, found that if these neurons are strongly activated by pulses of light, using a method called optogenetics, a male mouse will attack another male or even a female. However, weaker activation of the same neurons will trigger sniffing and mounting: mating behaviors. In fact, the researchers could switch the behavior of a single animal from mounting to attack by gradually increasing the strength of neuronal stimulation during a social encounter (inhibiting the neurons, in contrast, stops these behaviors dead in their tracks).
These results suggest that the level of activity within the population of neurons may control the decision between mating and fighting.
The neurons initially were identified because they express a protein receptor for the hormone estrogen, reinforcing the view that estrogen plays an important role in the control of male aggression, contrary to popular opinion. Because the human brain contains a hypothalamus that is structurally similar to that in the mouse, these results may be relevant to human behavior as well.
Even if there was no God, even if human beings had no soul, it would still be true that evolution had created a remarkable animal — the human animal — during its millions of years of labor. So very like our closest biological relatives, the chimpanzees, yet so different. For our study of the chimpanzees had helped to pinpoint not only the similarities between them and us, but also those ways in which we are most different. Admittedly, we are not the only beings with personalities, reasoning powers, altruism, and emotions like joy and sorrow; nor are we the only beings capable of mental as well as physical suffering. But our intellect has grown mighty in complexity since the first true men branched off from the ape-man stock some two million years ago. And we, and only we, have developed a sophisticated spoken language. For the first time in evolution, a species evolved that was able to teach its young about objects and events not present, to pass on wisdom gleaned from the successes — and the mistakes — of the past, to make plans for the distant future, to discuss ideas so that they could grow, sometimes out of all recognition, through the combined wisdom of the group.
What a totally normal thing to do!
… what …
We use CT scanning in trauma care so much that we tend to take it (and its safety) for granted. I’ve written quite a bit about thoughtful use of radiographic studies to achieve a reasonable patient exposure to xrays. But another thing to think about is the use of IV contrast.
IV contrast is a…
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University of Miami researchers develop a method to visualize protein interactions in a living organism’s brain
There are more than a trillion cells called neurons that form a labyrinth of connections in our brains. Each of these neurons contains millions of proteins that perform different…
Flatulent cows cause methane explosion on German farm
Yes, you read that right.
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