30 December 2011

Fine Tuning Brain Ensembles with Glial Overseers

Glia cells, named for the Greek word for "glue," hold the brain's neurons together and protect the cells that determine our thoughts and behaviors, but scientists have long puzzled over their prominence in the activities of the brain dedicated to learning and memory. Now Tel Aviv University researchers say that glia cells are central to the brain's plasticity — how the brain adapts, learns, and stores information.

...Almost all neurodegenerative diseases are glia-related pathologies, Prof. Ben-Jacob notes. In epileptic seizures, for example, the neurons' activity at one brain location propagates and overtakes the normal activity at other locations. This can happen when the glia cells fail to properly regulate synaptic transmission. Alternatively, when brain activity is low, glia cells boost transmissions of information, keeping the connections between neurons "alive." _aftau.org

To understand the brain, one must conceptualise multiple levels of activity occurring simultaneously. The level where glial cells influence neurons and synaptic output is a relatively low to mid-level, but a crucial one. Neuroscience has barely begun to understand this basic interaction between cell types, and is forced -- as in this study -- to use neurocomputational models in an attempt to expand the comprehension of this complex give and take.
The brain is constituted of two main types of cells: neurons and glia. Neurons fire off signals that dictate how we think and behave, using synapses to pass along the message from one neuron to another, explains De Pittà. Scientists theorize that memory and learning are dictated by synaptic activity because they are "plastic," with the ability to adapt to different stimuli.

But Ben-Jacob and colleagues suspected that glia cells were even more central to how the brain works. Glia cells are abundant in the brain's hippocampus and the cortex, the two parts of the brain that have the most control over the brain's ability to process information, learn and memorize. In fact, for every neuron cell, there are two to five glia cells. Taking into account previous experimental data, the researchers were able to build a model that could resolve the puzzle.

The brain is like a social network, says Prof. Ben-Jacob. Messages may originate with the neurons, which use the synapses as their delivery system, but the glia serve as an overall moderator, regulating which messages are sent on and when. These cells can either prompt the transfer of information, or slow activity if the synapses are becoming overactive. This makes the glia cells the guardians of our learning and memory processes, he notes, orchestrating the transmission of information for optimal brain function. _aftau.org

PLoS CompBio
Looking at how synaptic connections change during learning and memory is a little bit like trying to understand what goes on inside an office building by studying a set of architectural blueprints and reviewing the utility bills. It provides a bare beginning, but it's a start.
Synaptic plasticity is the capacity of a preexisting connection between two neurons to change in strength as a function of neuronal activity. Because it admittedly underlies learning and memory, the elucidation of its constituting mechanisms is of crucial importance in many aspects of normal and pathological brain function. Short-term presynaptic plasticity refers to changes occurring over short time scales (milliseconds to seconds) that are mediated by frequency-dependent modifications of the amount of neurotransmitter released by presynaptic stimulation. Recent experiments have reported that glial cells, especially hippocampal astrocytes, can modulate short-term plasticity, but the mechanism of such modulation is poorly understood. Here, we explore a plausible form of modulation of short-term plasticity by astrocytes using a biophysically realistic computational model. Our analysis indicates that astrocytes could simultaneously affect synaptic release in two ways. First, they either decrease or increase the overall synaptic release of neurotransmitter. Second, for stimuli that are delivered as pairs within short intervals, they systematically increase or decrease the synaptic response to the second one. Hence, our model suggests that astrocytes could transiently trigger switches between paired-pulse depression and facilitation. This property explains several challenging experimental observations and has a deep impact on our understanding of synaptic information transfer. _PLoSCompBio

PLoS Comp Bio
By understanding how synaptic frequencies can be modulated by changes in the glial::neuronal interaction, scientists can begin to bridge upward to the next higher levels of cognition -- local and distant neuronal ensembles. No one said it would be easy.

Neuroscientists are forced to work with a variety of animal models, human brain imaging techniques, cell culture approaches, and computational models, in order to enlarge their understanding of the foundations of an incredibly complex, multi-layered, and time-dependent phenomenon -- consciousness. And at that, we are talking about the consciousness of lower animals.

PLoS article in full
Bonus link: Wim de Neys at U. Toulouse is attempting to clarify some of the insights that come from the work of Nobel Prize winner Daniel Kahneman. de Neys seems to want to place human intuition on a higher level than the one on which Kahneman's work suggests it belongs. Certainly humans are dependent upon their intuitions for most of the things they do and virtually all the choices they make. In the opinion of Al Fin cognitivists, such psychological research still suffers from the lack of a firm neuroscientific foundation.

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29 December 2011

"Sea Tree," A Seastead for Birds, Fish, and Bats

The Sea Tree would be a tiered structure moored underwater with a cable that serves as the frame for series of layers. The layers above and below water would, over time become their own ecosystems — much like a sunken ship does underwater. Like an oil rig, the structure would rise above water and be self sufficient, but serves nature only.

The Sea Tree is a concept created by Amsterdam-based Waterstudio.nl. What is unique about this concept is that their plan was always to create the structure for nature only rather than retrofitting a green space into an urban structure or create a mixed use building. The idea was meant offset the trend of city sprawl and could be located in any water source — lakes, rivers or oceans. Wherever there is a need to bring some green back to the environment. _DVice
Humans have intentionally created artificial reefs for thousands of years for military purposes, and since the 17th century for purposes of increasing fish yields. Of course, humans have unintentionally created artificial reefs since the first ship sinkings and offshore garbage dumps.

Humans have also created island bird refuges for nesting birds, for some time.

This Dutch creation combines the artificial reef concept with the island bird refuge concept. To top it off, they have included an interior "bat cave" as a bat sanctuary and habitat.
A lush variety of plant life should provide abundant nesting areas for birds, as well as providing food for insects, which in turn provides food for birds, bats, and fish.
Once the multi-level animal seastead is placed off-limits to humans, it is apt to evolve its ecosystem in any number of directions. As an ecological experiment, it might hold more than a few surprises.

Just be sure to locate it away from any onshore or offshore wind farms, and keep feral cats far away. Maintenance would best be carried out by robotic telepresence. Monitoring should be done by webcam and UAV flyover. Keep tourists far away. Shoot to kill, if you must. ;-)

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Khan Academy to 4 Million Unique Monthly Visits

Forbes Video Network

Khan Academy is growing rapidly, thanks to economic backing from contributors such as Google and Bill Gates. Over 2600 videos are now offered, with more created every week.
Over the last month, Khan Academy saw 4 million unique users. That’s up from 1 million in the same period last year, and up from 3.5 million in October (asked by dbigthe)
The Khan Academy team is currently made up of 22 people, and they’re hiring ~1 more per month. (asked by dbigthe)
“I’d say that 90% [of the videos are shot] in 1 take. 99% are 2 takes.” (asked by johnsmcjohn)
“I will definitely do much more advanced mathematics in the next year than what we have now.” (This resulted in Michael Nielson, leading quantum computing expert and author of the standard text on the subject, to offer his assistance right in the thread) _TC
h/t Carpe Diem

Khan Academy is growing very rapidly -- adding topics, content, and better ways for teachers to use the content in the classroom. As more people get involved in the creative department, expect to see higher production values creeping into the routine.

As to whether KA will ever grow into an accredited provider of educational credentials, that depends a lot on where Salman Khan wants to go with the idea. At this point, he seems happy with the idea of creating a "log" of online activities as a type of student transcript. As the real world's attitudes toward education evolve, such informal proofs of mastery may be sufficient for many apprenticeships or jobs.

What seems more likely, is that an enterprising education entrepreneur will combine the best of Khan (mastery learning), Knewton (adaptive learning), and other e-learning methods into a low-cost, for-profit online institute for learning, from kindergarten to post-university and adult lifelong learning. The idea would include test prep, and a wide range of basic certifications, along with homeschool credentials at least through high school level.

College level accreditation for traditional degrees would likely require affiliation with established educational institutions. That would require deep pockets, given the mercenary nature of most university administrations. In today's economy, it might be best for such a startup to grab a profitable niche and expand from there, following a well-crafted long-term plan.

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Bringing Coral Reefs Rapidly Back From the Brink

"I was devastated. Basically, all the corals were dead. It was gravel and sand," Rani recalled.

But when German architect and marine scientist Wolf Hilbertz told her about a discovery he had made in the 1970s, the diver's ears pricked up. _Discovery


The story talks about how corals were killed by cyanide poisoning and dynamite fishing. The same kind of devastation of coral reefs occurs after severe storms. Fortunately, coral is incredibly prolific at spreading its seed far and wide across seas and oceans -- spreading over hundreds of miles from the parent reef.

Hilbertz had sought to "grow" construction materials in the sea, and had done so by submerging a metallic structure and connecting it to an electric current with a weak and thus harmless voltage.

...When he tested out his invention in Louisiana in the United States, Hilbertz saw that after a few months oysters progressively covered the whole structure, and colonized the collected limestone.

More experiments were carried out and the same phenomenon was confirmed for corals.

"Corals grow 2-6 times faster. We are able to grow back reefs in a few years," Thomas J. Goreau, a Jamaican marine biologist and biogeochemist, told AFP.

Goreau began working with Hilbertz in the mid-1980s to develop Biorock technology, and he has continued their work since Hilbertz's death four years ago.

When Rani saw the discovery, it gave her an idea for how she might save "her" bay.

She decided to expand the project to 22 structures using her own money with the help of Taman Sari, the holiday resort in front of the coral restoration project.

...Today there are around sixty of these "cages" in Pemuteran bay, across a surface of two hectares, and the reef has not only been saved from near-death, it is flourishing better than ever before.

"Now we've got a better coral garden than we used to have," said Rani.

Biorock not only revives the corals but it makes them more resistant... _Discovery
Of course, cyanide and dynamite -- not to mention storms and trophy-taking tourists -- are quite hard on a reef. How wonderful to find such an easy remedy for such an unsightly problem.

For reporters to claim that the fluctuating ocean temperatures are killing reefs -- reefs which evolved to survive in a wide range of temperatures and dissolved CO2 levels -- is pure dishonesty and political activism.

It is past time for science reporters to come clean, and to report science news honestly and in a balanced fashion. The current crop of science journalists too often come across as just plain biased and incompetent.

First published at Al Fin Potpourri


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America by Population Group

Images below are via Radical Cartography (h/t Foseti) Similar US maps available for percent Native American and percent Pacific Islander
A higher percent European population is generally seen in lower crime and higher income regions.
A higher percentage of persons of African descent is generally seen in high crime, low income regions. Blacks tend to concentrate in cities.
The "hispanic" category is misleading and confused. For US populations, "hispanic" typically refers to a range of mestizo populations from Mexico and Central America. It can also refer to Cuban immigrants, Puerto Rican immigrants, Europeans with Spanish names or to blacks with Spanish sounding names.

As one would expect with such a confused category, crime and poverty rates associated with a high "hispanic" percentage are mixed.
As with the hispanic category, the "Asian" category can refer to a wide range of population groups, from East Asians to South Asians to Southeast Asians, etc. In general, areas with higher "Asian" population percentages tend to have less crime and higher income.
Murder Rate per 100,000 in Large Cities

Trulia Crime Maps
The above map has a link to the Trulia.com crime map website, which will provide you with an incredible amount of "neighborhood-level" detail for crime in whichever city you select. Very useful for planning activities, and neighborhoods to avoid.

Crime rates in the US tend to be higher in cities -- particularly in cities with high black populations and high mestizo populations, with low European and Asian populations.
This map of Chicago gives an idea of the level of segregation one can find within US cities, over 40 years after affirmative action and desegregation policies were put in place. In high black percentage areas and neighborhoods within cities, crime and poverty rates tend to be significantly higher than in areas where black population percentages are lower. That simple fact goes a long way toward explaining the voluntary segregation one finds -- those who can move away from the crime and poverty tend to do so.

If black crime were eliminated from US crime statistics, violent crime rates in the US would be comparable to those in the most peaceful of European states.

More information, taken from official US government crime statistics, on racial disparities in US crime:
  • Blacks are seven times more likely than people of other races to commit murder, and eight times more likely to commit robbery.
  • When blacks commit crimes of violence, they are nearly three times more likely than non-blacks to use a gun, and more than twice as likely to use a knife.
  • Hispanics commit violent crimes at roughly three times the white rate, and Asians commit violent crimes at about one quarter the white rate.
  • The single best indicator of violent crime levels in an area is the percentage of the population that is black and Hispanic.
_Color of Crime
Download full PDF report: Color of Crime

America is a complex mix of peoples, varying widely by geography and by sub-regions within particular regions and cities. Rates of poverty, crime, corruption etc. vary widely across the regions of the US. Some of these differences can be associated with differences in racial and cultural compositions of these different regions and sub-regions.

If you are planning a visit to the US, please take these differences into account in your planning, for your own safety. If you are planning to re-locate to the US, or are re-locating from one area within to the US to another, please consider the issues presented here, for your own and your families' sakes.

Of course, it could be a lot worse. We could be talking about South Africa:
With 50 murders and 40 ‘culpible homicides’ a day, South Africa has the world’s highest daily violent-death rates.

By comparison, the United States’ city of New Orleans, which holds the dubious distinction of being the ‘murder capitol of the USA,’ records 80 murders A YEAR. _Source
More: The global crime rate map (Economist via Mises Institute) and Wikipedia crime rate table below, may provide a foundation for understanding patterns of crime within different populations within the US:

 El Salvador[7][8]66
 Saint Kitts and Nevis[7]38
 Trinidad and Tobago[12][13]37
 South Africa[14]32
 Dominican Republic[7]25
 Saint Lucia[7]25
 Saint Vincent and the Grenadines[7]22
 Costa Rica[7][8]11
 Antigua and Barbuda[7]6.8
 United States[19]4.8
The Wikipedia table above lists intentional homicides per 100,000 population. It is hampered by the fact that many of the third world nations of the world are unable to maintain accurate statistics of this nature, and tend to understate their own murder and homicide rates as an inadvertent routine. Leave it as an exercise to guess which nations that should be listed prominently near the top, are not.

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