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Joelle Bernier, a researcher from Quebec (Canada), has conducted experiments that show how neurons are created in adult brains. Until a few years ago, neurons were thought to be created only at childhood. Then we observed neurons being created in a part of the brain.
Bernier's experiments show neurons being created in the amygdala of the adult brain. The amygdala is an important center for processing emotions, and in particular "fear".
Research on the origin and maintenance of biological diversity has led
biologists to discover that diversity of animal species and diversity of human languages go hand in hand, i.e.: cultural and biological diversity are lowest and highest in the same places.
In other words, areas with the most animal species also contain the greatest number of human languages.
Danish biologist Carsten Rahbek , in collaboration with
British biologists Andrew Balmford and Joslin Moore of Cambridge University,
has created a database on the distribution
of all African mammals, birds, snakes and amphibians, that lists about
By using this database, he can study patterns of species distribution and
their relationship with human activity. It turns out that areas inhabited by
many animal species are also the areas where humans speak many languages,
Of course, the relationship could be a mere coincidence. Other factors influence
biological diversity (i.e., the weather) and perhaps the same factors end up
influencing language diversity.
The Australian chemist Edith Sevick has conducted experiments that show it is possible
to break the second law of thermodynamics at the level of atoms and molecules.
The second law of thermodynamics is the one that introduced the popular concept
of entropy: entropy can never decrease in a closed system. In other words,
if the system is closed (i.e., it is not being operated upon by another system),
it drifts towards absolute chaos and no information. A very good example of
this law is that your house needs maintenance: problems don't fix themselves,
you have to fix them. A system spontaneously loses "order" and "information",
whereas order and information can be increased only by an external force.
An alternative way of expressing this concept is that
some energy is always lost when converting from one type of energy to another,
i.e. whenever the system "does" something.
The British physicist James Clerk Maxwell (famous for having unified electricity
and magnetism and opened the way for Einstein's special theory of relativity)
had already noted more than a century ago that the second law of thermodynamics
is a "statistical" truth, not a mathematical one. A system is made of many
particles. Properties due to the ensemble of particles are "statistical" because
they simply express the fact that a "majority" of particles exhibit those
properties (not necessarily every single particle does).
Therefore the second law of thermodynamics does not completely rule out the
possibility of decreasing entropy.
Denis Evans and Sevick has shown is that the second law of thermodynamics is continually
being violated at the level of microscopic particles (albeit only for very
short periods of time), although if you
consider the whole system the second law of thermodynamics is always confirmed
(see her paper).
Sevick's study could eventually introduce a new fundamental property of nature,
and a new fundamental limit. What her experiment shows is that, at some very
small scale, machines would stop working the way they work at the scale we
are used to. Thus, there would be a natural limit to miniaturization (machines
would literally start working backwards if you make them "too small").
And this would, obviously, have an impact on things such as computers.
- In the quest for an explanation of dark matter and dark energy,
the American physicist Paul Steinhardt and the British physicist Neil Turok
have proposed the
Cyclic Universe Theory,
according to which there is no "big bang" to begin with, and there will be no "big crunch"
to end with.
Space and time existed ever since and will exist forever. There is
no beginning or end. The evolution of the universe is due to
a series of "bangs" (explosive expansions) and "crunches"
(contractions). The big bang that we observe today with the most powerful
detectors of microwaves is simply one of the many expansions following
one of the many contractions. Each phase may last a trillion years, and
therefore be undetected by human instruments. The cyclic nature of the
universe would be due to "negative potential energy", a concept arising from
string theory, rather than General Relativity's spatial curvature.
In principle, this is the same idea advanced by
the QSSC (Quasi Steady State Cosmology)
of British physicist Geoffrey Burbidge
and his collaborators Fred Hoyle and Jayant Narlikar.
In fact, it is more orthodox than it may sound. Totally lacking is Burbidge criticism of black holes,
quasars and the cosmic radiation.
- The American neurologist
has been studying the different use of the brain by children and adults.
His theory is that the very same tasks are performed by children and adults
using different brain regions. As the human brain matures, some functions
are offloaded to other regions. Why this is happening and when it stops
happening is the mystery that Schlaggar is trying to solve.
It could be that some connections among brain regions are not mature enough
in the early years of life. But why some regions would be better than others
for performing some functions is still not clear. What is clear is that,
as we grow up, we change the way we use our own brain.
- "Ecological population genetics" is the study of why and how living beings
are the way they are within the environment that they inhabit.
Insect colonies (and particularly ant colonies) are a favorite subject to study
because they tend to have the most complex social organization.
They are typically divided into different castes with different functions.
For a long time there has been a debate on how such castes arise.
One theory is that they are determined by the environment: there is nothing at
birth to differentiate a worker from a warrior, just like there is nothing
genetically different between a human being who works in a factory and a human
being who fights in a war. In this sense, society is basically "forced" upon
the colony: environmental pressures force living beings to get organized in
societies. Instead, Stanford Univ's biologists Deborah Gordon and Veronica Volny
have recently shown that there is a genetic determination of who does what.
While studying the caste system of the red harvester ant, they found out that
a queen mates with different males and the offspring belongs to a caste or
another depending on the male. The castes are a product of the sexual behavior
of the queen.
German anthropologist Svante Paabo
has found the first evidence of what causes the differences in behavior between
chimpanzees and humans (who share 99% of their genes).
In 1997 Paabo showed that the Neandertal man's DNA sequence falls outside the
normal variation of modern humans. In other words, Neandertals were not our ancestors.
Using a similar technique, biologists can show that the genes of
chimpanzees and humans are mostly identical. It is a mystery why humans behave
in such a different way. Their brains are amazingly similar.
Proving that "pattern" and not "topology" determines what goes on inside the
brain, Paabo's studies show that gene activity (i.e., production of protein)
in the cerebral cortex of humans is five times more intense than in chimps.
Human brains simply evolved five times faster than chimpanzee brains.
Christof Koch and his team have been investigating the portion of the
brain in charge of visual processing.
The idea is that visual processing is a function that generates consciousness
of something out of integrating so many different inputs, and therefore
is a good indication of how consciousness works.
Koch is looking for the "neural correlates" of conscious experience, i.e.
the neural activity related to the creation of a conscious experience.
Koch's articles basically detail his quest for the area in the brain where
(see for example,
The problem is that every year there seems a new area that is also involved...
- The South-African anthropologist
has moved back the birthdate of thinking by about 40,000 years.
Humans have existed for a very long time, but there is scant evidence that they were
"thinking" until very recently. The cave paintings have been the strongest evidence yet
for some kind of symbolic thinking (I paint something that refers to something else).
In a Southafrican cave, Henshilwood discovered two pieces of ochre with geometric
patterns, which could be symbolic artwork that would predate the oldest known
cave paintings by more than 40,000 years.
Some anthropologists and psychologists argue that the faculty of thinking developed
suddenly, in a relatively short and intense burst of creativity, whereas others
think that it developed gradually and slowly over many thousand years. If you believe that
our evolutionary history parallels our developmental story (i.e., how we turn from
children to adults) you tend to side with the former theory. If you believe that
thinking followed the general patterns of anatomical evolution, you may side with
the latter theory. The further back art objects go, the higher it is that the
latter theory is right.
An article on this finding
In the 1950s, the Russian psycho-physicist Yarbus realized that
human beings do not scan a scene in a raster-like fashion. On the contrary, we jump
from one point to the next one, in an apparently random manner. We only fixated for a
very short period on each point.
A "saccade" is a rapid eye movement that occurs while we are awake. Saccades occur
several times a second. Basically, our eyes continuously scan the environment.
In order to do this, our eyes need to continuously "refocus".
"Saccadic eye movements" are opposed to the
"pursuit eye movements", the slow, smooth eye movements that follow a steadily moving
Saccadic eye movements
are interesting because it may tell us a lot about how our brain works and, in particular,
about the other "rapid eye movement", the one that occurs while we are sleeping
(see this introduction
to eye movements,
see this introduction
to saccadic movements,
see this seminar,
and, for example, this paper).
The mystery, of course, is how can we perceive a stable world when our eyes are continuously
changing target (a phenomenon known as "visual stability").
We should be perceiving a rather messy and frantic world.
The German neurologist Alex Thiele is studying neuronal
activity related to saccadic eye movement. His findings prove that the brain regulates
the saccadic eye movement and "suppresses" some of the information in order to present
a world as stable as possible.
Saccades have been found to be shortcuts to relevant information in the environment.
Since we cannot store the entire world in our brain, we simply store pointers to what
is truly important in the environment. When we need to retrieve information, we use
saccades. Basically, we retrieve information as we need it, instead of storing it
permanently in our brain.
Yarbus already knew that, while apparently random, the pattern of saccadic eye movements
depends on the cognitive task to be performed (on what information we need to retrieve).
For example, when we need to identify someone, the saccadic eye movements focus mostly on
the eyes and the mouth.
These are the regions that we mostly rely on for face recognition.
Saccadic eye movement is not a random sampling of the environment, but a highly specific
indexing of relevant information in the environment.
- The American neuroscientist
Matthew Wilson from the Centre for Learning and Memory at the MIT
is studying the way experience is represented and stored in the brain of rats.
The idea is that one can examine the patterns of neural activity in the brain
and relate those patterns to something that happened to the individual (rat) and
that is being processed in the brain.
The same studies can be applied to dreams.
Dreams are widely believed to be a means to consolidate memories acquired during
the day, by playing them against the genetic repertory and moving them from
short-term memory to long-term memory.
For example, patterns of neural activity in the hippocampus
that occurred during the day will reoccur during sleep periods.
By observing which neural patterns arise (and by correlating them to previous
neural activity), one can actually guess what the rat is dreaming of.
- The American psychiatrist Gregory Berns (of Emory University)
is studying the brain circuits that are responsible for impulsive behavior such as playing the stock market, gambling, rooting for a soccer team. It turns out these are the same brain circuits that
evolved to help us cope with survival issues (food, sex, danger). Those brain
circuits are largely outside the sphere of influence of your "conscious"
experience. We react by "instict" to those survival issues.
Our brain seems to be built in such a way as to avoid "thinking" about issues
that are a matter of life and death. As we acquire data from our surroundings,
some of them are first processed by the
and are "perceived" only after a response has already been programmed.
The fact that trivial chores, such as investing in the stock market or rooting
for a soccer team, also fall outside "conscious experience" lends credence to
the theory that "most" of our cognitive life is unconscious. Several cognitive
scientists believe that we "think" only after we have already acted, and our
self-awareness is a mere illusion. I pretend that I have been writing these
lines because I wanted to, but in reality I wrote them under some kind of
unconscious impulse and only afterwards do I realize that I wrote them.
It all goes back to the circuits in the brain that pilot our behavior in the
face of rewards.
The circuits that assess "rewards" are driven by a chemical called dopamine,
and are therefore referred to as the "dopamine system".
In 1997 Swiss neuroscientist Wolfram Schultz
developed a theory of how the dopamine system affects learning through the
concept of "reward".
Dopamine neurons respond to rewards. A good reward increases the activity
of dopamine neurons, a mediocre reward has no effect on them and a
disappointment (the opposite of a reward) depresses their activity.
Basically, the dopamine system is an alarm bell. If the dopamine system is
stable, the brain does not have to look into what has happened: the world
is under control. If the dopamine system is subject to a change, then the
brain has to look into what happened and "learn" something new: the reward
signals that the action was a useful one, the disappointment signals that the
action was a bad one. Whenever the dopamine system gets excited or depressed,
some kind of learning occurs in the brain.
While depevoled for survival purposes, the same dopamine system is vulnerable
to "rewarding" signals from, say, the stock market and gambling.
The American anthropologist Michael Alvard
has advanced the theory that the social behavior of humans arose with the
adoption of carnivorous habits. Hunting is a cooperative process that may have
fostered the evolution of cognitive skills such as altruism and language, and
even politics and economy.
The transition from solitarty foraging to group hunting changed the environmenal
pressure that early hominids were subject to.
Alvard also points out that the distribution of meat had to be "fair" in order
to motivate individuals to cooperate (each individual had to "gain" something
proportional to his contribution to the hunt). In other words, hunters needed
relatively complex behavior, compared with solitary foragers.
- While studying the brain of monkeys, Ryohei Hasegawa of Kyoto University
and National Eye Institute
has discovered that neurons reflect past and predicted performance
much more than they reflect current performance.
(See their paper)
Basically, the brain does not store current activity, but immediately computes
future behavior in the face of a similar situation plus a "summary" of past
events. Neurons are basically machines to predict the future.
(See the debate on this experiment).
- Chris Goodnow of the John Curtin School (Canberra, Australia, (His home page)
and his student Stephen Martin (His home page)
are studying immunological memory, or how the immune system remembers.
Since we have learned of so many analogies between the immune system and the
brain, this research could lead to a better understanding of brain memory
as well. There is a kind of cell that provides a sort of barrier to
future infections. Martin is trying to understand this kind of cell.
An abstract of their work).
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