LONDON – Scientists have discovered a new source for the generation of nerve cells in the brain.

Professor Magdalena Gotz of Helmholtz Zentrum Munchen and Ludwig-Maximilians-Universitat (LMU) Munich and colleagues have discovered progenitor cells, which can form new glutamatergic neurons following injury to the cerebral cortex.

Particularly in Alzheimer’s disease, nerve cell degeneration plays a crucial role. In the future, new therapeutic options may possibly be derived from steering the generation and/or migration mechanism, according to the researchers.

Until only a few years ago, neurogenesis – the process of nerve cell development – was considered to be impossible in the adult brain.

Then researchers discovered regions in the forebrain in humans in which new nerve cells can be generated throughout life. These so-called GABAergic cells use gamma-aminobutyric acid (GABA), a neurotransmitter of the central nervous system.

Now, the research team, led by Gotz, has taken a closer look at this brain region in the mouse model. They found that even in the forebrain, there are other nerve cells that are regularly generated – the so-called glutamatergic nerve cells, which use glutamate as neurotransmitter.

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They say you can’t teach an old dog new tricks, but scientific findings seem to indicate otherwise. Research shows that our brains literally rewire in response to new stimulation. And when it comes to computer use, Internet activity may stimulate and possibly improve brain function, according to scientists at UCLA.

“Technology may be changing our minds and changing the way we think,” said Dr. Gary Small, a neuroscientist speaking last month at the UCLA Technology & Aging Conference at the Skirball Cultural Center.

Small, director of the UCLA Center on Aging, described results of research he and colleagues performed with volunteers between the ages of 55 and 76. Half of the participants were familiar with how to search the Internet, and the other half were new to it. The participants engaged in Internet searching while simultaneously undergoing functional magnetic resonance imaging (MRI).

The MRI images clearly showed activity in the areas of the brain that control decision-making and complex reasoning — but only in the Web-savvy group. The inexperienced group showed no such activity.

However, after just five one-hour sessions of practice, the Web newbies showed activation in the same areas of the brain as the savvy group.

“Five hours on the Internet and the naive subjects had already rewired their brains,” said Small, writing about the findings in “iBrain: Surviving the Technological Alteration of the Modern Mind” (HarperCollins). “Recent studies demonstrate that older brains do remain malleable and plastic throughout life. Even areas of the brain that were reserved for specialized tasks can be recruited and retrained.”

In other words, “use it or lose it” applies to the brain. Indeed, Small notes, “Several studies have shown that exercising the brain with mental aerobics not only can improve cognitive performance scores but also may delay brain degeneration.”

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The ability of humans to learn, remember, and adapt is directly related to the changeableness (plasticity) of the human brain. Whenever we learn new information, the connections between nerve cells in the brain are modified. The activity of some connections (called synapses) increases, while the activity of other synapses decreases. The initial changes involve local chemical alterations in the way synapses transmit and receive information from other neurons. These initial chemical changes eventually lead to structural changes in the brain; that is, more connections and more complex connections form. The longer lasting of these changes require the turning on and turning off of specific genes; therefore, learning involves gene expression. Changes in synaptic connections represent a major way by which memories are formed. But some memories fade, and it is likely that the newly formed connections must be reinforced by ongoing brain activity in order for these connections to survive. The important points to remember are that learning alters the actual structure of the brain and that genes are involved in learning.

Neurogenesis

Neurogenesis (the formation of new nerve cells in the adult brain) is really part of the larger story about brain plasticity. Neurogenesis reflects the amazing resilience and plasticity of our brains. Expanding upon observations initially made years ago about birds, it has become clear that certain parts of the human brain are capable of generating new neurons throughout life, even during old age.  Not all regions of the brain appear to have this ability to grow new nerve cells, but two regions, the dentate gyrus of the hippocampus and the areas near the lateral ventricles in the olfactory system (which is involved in the sense of smell), are really good at it. The dentate gyrus plays a key role in the function of the hippocampus, the region that is so critical for memory processing. A thousand or more new neurons are born in this region each day and can be incorporated into the circuitry of the hippocampus where they help enhance certain types of learning. These new neurons may be particularly important for processing new information.

To make memories, new neurons must erase older ones

Short-term memory may depend in a surprising way on the ability of newly formed neurons to erase older connections. That’s the conclusion of a report in the November 13th issue of the journal Cell, a Cell Press publication, that provides some of the first evidence in mice and rats that new neurons sprouted in the hippocampus cause the decay of short-term fear memories in that brain region, without an overall memory loss.

The researchers led by Kaoru Inokuchi of The University of Toyama in Japan say the discovery shows a more important role than many would have anticipated for the erasure of memories. They propose that the birth of new neurons promotes the gradual loss of memory traces from the hippocampus as those memories are transferred elsewhere in the brain for permanent storage. Although they examined this process only in the context of fear memory, Inokuchi says he “thinks all memories that are initially stored in the hippocampus are influenced by this process.”

In effect, the new results suggest that failure of neurogenesis will lead to problems because the brain’s short-term memory is literally full. In Inokuchi’s words, we may perhaps experience difficulties in acquiring new information because the storage capacity of the hippocampus is “occupied by un-erased old memories.”

Of course, Inokuchi added, “our finding does not necessary deny the important role of neurogenesis in memory acquisition.” Hippocampal neurogenesis could have a dual role, he says, in both erasing old memories and acquiring new ones.

Earlier studies had shown a crucial role for the hippocampus in memorizing new facts. Studies in people with impaired and normal memories and in animals also showed that information recall initially depends on the hippocampus. That dependence progressively decays over time as memories are transferred to other regions, such as the neocortex. Scientists have also observed a similar decay in the strength of connections between neurons of the hippocampus, a phenomenon known as long-term potentiation (LTP) that is considered the cellular basis for learning and memory.

Scientists also knew that new neurons continue to form in the hippocampuses of adults, even into old age. But it wasn’t really clear what those newborn brain cells actually do. Inokuchi’s team suspected that the integration of new neurons was required to maintain neural connections, but they realized it might also go the other way. The incorporation of new neurons into pre-existing neural circuits might also disturb the structure of pre-existing information, and indeed that is what their new findings now show.

The researchers found that irradiation of rat’s brains, which drastically reduces the formation of new neurons, maintains the strength of neural connections in the hippocampus. Likewise, studies of mice in which hippocampal neurogenesis was suppressed by either physical or genetic means showed a prolonged dependence of fear memories on that brain region.

On the other hand, voluntary exercise, which causes a rise in the birth of new neurons, sped up the decay rate of hippocampus-dependency of memory, without any memory loss.

“Enhanced neurogenesis caused by exercise may accelerate memory decay from the hippocampus and at the same time it may facilitate memory transfer to neocortex,” Inokuchi said. “Hippocampal capacity of memory storage is limited, but in this way exercise could increase the [brain's overall] capacity.”

The study sets the stage for further examination of the connections between neurogenesis and learning capacity, the researchers say. They also plan to examine how the gradual decay of memory dependence on the hippocampus relates to the transformation of memory over time from a detailed and contextually-rich form to a more generic one.

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Drinking eight cups of tea daily might sound a bit too much for some people, but health experts say the intake can help fight heart disease, improve brain power and also boost longevity.

Independent Dietician, Dr. Carrie Ruxton’s research on caffeine at King’s College, London, saw her review 47 published studies to reach the conclusion that caffeinated drinks such as tea, coffee and cocoa have positive effects on mental function, increasing alertness, feelings of well-being and short-term memory.

Previous studies have already linked the drink’s healthy antioxidant properties and high flavonoid content to preventing heart disease and cutting the risk of some cancers.

Ruxton has supported earlier reports by claiming that an optimal intake of 400mg of caffeine a day leads to “key benefits in terms of mental function and heart health”.

She assessed three studies, accounting for almost 90,000 patients, to find that drinking four cups of tea or coffee a day reduced chances of cardiovascular disease.

She referred to another study of 26,500 middle-aged smokers, which hinted that men who ingested more than two cups of tea a day pulled down the probability of getting a stroke by 20 percent.

Ruxton insisted that she aimed to “debunk” false beliefs surrounding caffeine.

Moreover, she asserted that people who avoid drinking team might be doing more harm than good.

“People who cut out caffeinated drinks may miss out on the potential health benefits of the compounds they contain,” the Daily Express quoted her as saying.

She further suggested that there was “no need” for parents to stop children from drinking tea and coffee. In fact, she claimed it was better than juice in some regards.

Also, Dr Catherine Hood, of the Tea Advisory Panel, agreed to Ruxton’s claims.

She said, “Caffeinated drinks have been unfairly demonized. Black tea, in particular, contains polyphenols, which are natural plant antioxidants.”

“These have beneficial effects on many biochemical processes in the body because they protect cells against harmful free radicals.” she said.

“Flavonoids are thought to be especially useful, with a number of studies reporting a link between them and lower risk of heart attack.” she added.

Another way to improve your brain is push your brain in novel ways by playing Myfitbrain.

By Catherine E. Myers, Ph.D.

By Laura Sanders, Science News

CHICAGO — A toned, buff bod isn’t the only thing a workout is good for. Exercise protects special brain cells in monkeys’ brains and improves motor function, a new study finds. The data, presented at a news briefing October 18 in Chicago at the Society for Neuroscience’s annual meeting, adds to a growing body of evidence that shows exercise is good for the brain, too.

“This is sort of a quiet revolution that’s been occurring in neuroscience,” says Carl Cotman, a brain aging expert at the University of California, Irvine, “to realize that physical activity at a certain level impacts the brain in a really profound way.”

In the new study, researchers led by Judy Cameron of the University of Pittsburgh trained six adult female rhesus monkeys to run on treadmills built for humans. Over a period of three months, monkeys either ran, jogged or sat on a treadmill for five hours each week. Monkeys that ran got their heart rates to about 80 percent of maximum, comparable to a human training program that would increase cardiovascular fitness. The jogging monkeys’ heart rates reached about 60 percent of maximum.

After this training period, the researchers hit the right side of the monkeys’ brains with a neurotoxin called MPTP, designed to selectively kill neurons that produce the signaling chemical dopamine. These neurons, and the dopamine they produce, regulate movement, and are the very same ones that die in people with Parkinson’s disease.

Sedentary monkeys showed the expected decrease in these dopamine neurons on the right side of the brain after the neurotoxin was applied. But in the brains of monkeys that had run for the past three months, the neurotoxin had almost no effect. In the runners, dopamine neurons were just as plentiful on the right side of the brain as on the left.

Jogging also had a protective effect, although slightly weaker than running’s, Cameron says. “This is really good news. It means that any little bit more activity you can do is positive for your brain,” says Cameron. “Your brain seems very sensitive to exercise.”

When the researchers continued the experiment for another six weeks, the results held. A brain scan revealed that “the animals that were exercising had virtually no loss of dopamine in those neurons,” Cameron says. “We think that exercise is very neuroprotective.”

Next, the researchers assessed the monkeys’ ability to use the hand affected by the neurotoxin. Monkeys had to retrieve a Lifesaver candy from a thin wire, an experiment designed to test motor coordination. Sedentary monkeys could not use their left, affected hand at all, while the runners showed no difference between their left and right hands, the researchers found.

The new study highlights the importance of exercise for maintaining a healthy brain. Other studies presented at the meeting have found that exercise has a wide range of brain-protective roles in mice, monkeys and humans.

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