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Wednesday, 9 December 2009

The power of Nature, 2009

-a wonderful gallery of stuff inside your body-

Today:

  1. Girl with half a brain retains full vision
  2. Ants more rational than humans Parasite causes zombie ants to die in an ideal spot
  3. Brain cells have natural resistance to HIV
  4. Parasite causes zombie ants to die in an ideal spot
  5. Scientists find that individuals in vegetative states can learn

This will be again a post without a lot of comments. Just enjoy the power of Nature. It is really amazing.

Girl with half a brain retains full vision

A 10-year old girl born with half of her cerebral cortex missing sees perfectly because of a massive reorganisation of the brain circuits involved in vision, a new study finds.

Doctors discovered that she was missing the right half at the age of three, after she began suffering from seizures.

However, the seizures proved treatable and the girl – known as AH – lives an otherwise normal life. The left side of her body is slightly weaker than the right, but this hasn't stopped her from bicycling or roller-skating.

But what's most amazing, Muckli says, is her ability to see out of the left and right visual fields. Patients who have half of their cortex removed to treat epilepsy invariably lose half of their visual field.

AH, on the other hand, has no right hemisphere to receive any signal from her left visual field. What's more, her right eye never developed, so she should get visual information only from one half of her left eye – that is, from just one nerve bundle.

Brain scans performed by Muckli's team explain why that's not the case. Her retinal nerves that should normally connect to the right half of her brain instead set up shop in two parts of the left brain: the thalamus and the visual cortex.

In some cases, the diverted nerves seemed to have followed the molecular cues that would have guided nerves from the right eye, were they not missing. But for the most part, the left visual field neurons carved out their own islands in the right brain, Muckli says.

This kind of organisation allows AH's brain to process the left and right fields of vision distinctly from one another, ensuring that she sees both halves of her world. source

Ants more rational than humans

July 24th, 2009
This is not the case of humans being "stupider" than . Humans and animals simply often make irrational choices when faced with very challenging decisions, note the study's architects Stephen Pratt and Susan Edwards.

"This paradoxical outcome is based on apparent constraint: most individual ants know of only a single option, and the colony's collective choice self-organizes from interactions among many poorly-informed ants," says Pratt, an assistant professor in the School of Life Sciences in ASU's College of Liberal Arts and Sciences.

The authors' insights arose from an examination of the process of nest selection in the ant, Temnothorax curvispinosus. These ant colonies live in small cavities, as small as an acorn, and are skillful in finding new places to roost. The challenge before the colony was to "choose" a nest, when offered two options with very similar advantages.

What the authors found is that in collective decision-making in ants, the lack of individual options translated into more accurate outcomes by minimizing the chances for individuals to make mistakes. A "wisdom of crowds" approach emerges, Pratt believes.

"Rationality in this case should be thought of as meaning that a decision-maker, who is trying to maximize something, should simply be consistent in its preferences." Pratt says.

"Typically we think having many individual options, strategies and approaches are beneficial," Pratt adds, "but irrational errors are more likely to arise when individuals make direct comparisons among options."

"It is hard to say. But it's at least worth entertaining the possibility that some strategic limitation on individual knowledge could improve the performance of a large and complex group that is trying to accomplish something collectively," Pratt says. source

My comment: Collective intelligence, everyone :) I'm quite a fan of this, even leaving Star Trek aside. It's amazing how well the ant society functions. Of course, we don't know if the ants are happy or sad about their situation or even if they have feelings at all, but still, I'm awed by the amplification that cooperative effects provide. I mean compare the feeling of listening to music on your own with going to a concert. It's a qualitatively different state of mind. And the only difference (apart from the noise level and the smelling bodies around) is in the number of people that share your experience. Ok, long subject, really, but there is so much to meditate upon in it.

Brain cells have natural resistance to HIV

Neurons can protect themselves against infection with HIV, new research has demonstrated. They owe their hardiness to a protein called FEZ-1, made uniquely by neurons, and which appears to lock out the virus.

The finding raises the possibility of new treatments to thwart HIV by using gene therapy or drugs to activate production of the same protein in cells other than neurons – especially the white blood cells most vulnerable to infection.

Mojgan Naghavi of University College Dublin, Ireland, along with her colleagues Juliane Haedicke and Craig Brown, established the protective effects of FEZ-1 by blocking production of the protein in human neurons.

When they did this, the neurons became vulnerable to infection. Likewise, they successfully blocked the usual infections in other types of brain cells, such as microglia, by engineering them to manufacture FEZ-1.

Next, the researchers hope to see if they can block HIV infection in white blood cells by genetically engineering them to produce FEZ-1. They also hope to find out more about how The only other established source of natural protection against infection is in people who can't make CCR5, a surface protein that HIV uses to gain entry to cells.

Drugs already exist to block CCR5, and other teams are testing gene therapies to restock patients' blood with cells engineered to not produce CCR5. source

Parasite causes zombie ants to die in an ideal spot

August 11th, 2009

A study in the September issue of The American Naturalist describes new details about a fungal parasite that coerces ants into dying in just the right spot -- one that is ideal for the fungus to grow and reproduce.

When a carpenter ant is infected by a fungus known as Ophiocordyceps unilateralis, the victim remains alive for a short time. The fungus, however, is firmly in the driver's seat. It compels the ant to climb from its nest high in the forest canopy down into small plants and saplings in the understory vegetation. The ant then climbs out onto the underside of a low-hanging leaf where it clamps down with its mandibles just before it dies. There it remains, stuck fast for weeks.

After the ant dies, the fungus continues to grow inside the body. After a few days, a stroma—the fungus's fruiting body—sprouts from the back of the ant's head. After a week or two, the stroma starts raining down spores to the forest floor below. Each spore has the potential to infect another unfortunate passerby.

At a field site in a Thai forest, Hughes's team found that the infected carpenter ants are almost invariably found clamped onto the undersides of leaves that are 25 centimeters (about 10 inches) from the ground below. What's more, most of the dead ants were found on leaves sprouting from the northwest side of the plant. Interestingly, the researchers found that temperature, humidity and sunlight in these spots are apparently optimal for the fungus to grow and reproduce. When the researchers placed leaves with infected ants at higher locations, or on the forest floor, the parasite failed to develop properly.

"The fungus accurately manipulates the infected ants into dying where the parasite prefers to be, by making the ants travel a long way during the last hours of their lives," Hughes said.

As the fungus spreads within a dead ant's body, it converts the ant's innards into sugars which are used to help the fungus grow. But it leaves the muscles controlling the mandibles intact to make sure the ant keeps its death grip on the leaf. The fungus also preserves the ant's outer shell, growing into cracks and crevices to reinforce weak spots. In doing this, the fungus fashions a protective coating that keeps microbes and other fungi out. At that point, it can safely get down to the business of claiming new victims.

Carpenter ants apparently have few defenses against the fungus. The most important way they avoid infection seems to be staying as far away from victims as possible. That may be part of the reason why these ants make their nests in the forest canopy, high above fungal breeding zones. Carpenter ants also seem to avoid blazing their foraging trails under infected areas.

The mechanisms and cues the uses to control an ant's behavior remain unknown. source

My comment: Oh, that is so awesome! I mean seriously - a fungus that knows precisely what it's doing! It's even somewhat scary! They make the ant go precisely where they want it, they eat only specific tissues ...Come on. This sounds so intelligent. If we have then on our Planet, just imagine what we can find on other planets.

Scientists find that individuals in vegetative states can learn

September 20th, 2009

Scientists have found that some individuals in the vegetative and minimally conscious states, despite lacking the means of reporting awareness themselves, can learn and thereby demonstrate at least a partial consciousness.

It is the first time that scientists have tested whether patients in vegetative and minimally conscious states can learn. By establishing that they can, it is believed that this simple test will enable practitioners to assess the patient's consciousness without the need of imaging.

By using classical Pavlonian conditioning, the researchers played a tone immediately prior to blowing air into a patient's eye. After some time training, the patients would start to blink when the tone played but before the air puff to the eye.

This learning requires conscious awareness of the relation between stimuli - the tone precedes and predicts the puff of air to the eye. This type of learning was not seen in the control subjects, volunteers who had been under .

The researchers believe that the fact that these patients can learn associations shows that they can form memories and that they may benefit from rehabilitation.

Additionally, this research suggests that if the patient shows learning, then they are likely to recover to some degree."

In 2006, the Cambridge Impaired Group at the Wolfson Brain Imaging Unit showed, using functional imaging, showed that patients in vegetative states (as defined by behavioural assessment in the clinic) can in fact be conscious despite being unable to show consistent voluntary movements. source

My comment: (read the comments for more). As for me, it really proves just a capability of stimuli connections but still, it's very interesting.

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