Friday, 16 November 2012

Brainy beverage: Study reveals how green tea boosts brain power

It has long been believed that drinking green tea is good for the memory. Now researchers have discovered how the chemical properties of China's favorite drink affect the generation of brain cells, providing benefits for memory and spatial learning.

The research is published in Molecular Nutrition & Food Research.

"Green tea is a popular beverage across the world," said Professor Yun Bai from the Third Military Medical University, Chongqing, China. "There has been plenty of scientific attention on its use in helping prevent cardiovascular diseases, but now there is emerging evidence that its chemical properties may impact cellular mechanisms in the brain."

Professor Bai's team focused on the organic chemical EGCG, (epigallocatechin-3 gallate) a key property of green tea. While EGCG is a known anti-oxidant, the team believed it can also have a beneficial effect against age-related degenerative diseases.

"We proposed that EGCG can improve cognitive function by impacting the generation of neuron cells, a process known as neurogenesis," said Bai. "We focused our research on the hippocampus, the part of the brain which processes information from short-term to long-term memory."

"We have shown that the organic chemical EGCG acts directly to increase the production of neural progenitor cells, both in glass tests and in mice," concluded Bai. "This helps us to understand the potential for EGCG, and green tea which contains it, to help combat degenerative diseases and memory loss."

This paper is published as part of a collection of articles bringing together high quality research on the theme of food science and technology with particular relevance to China. Browse free articles from Wiley's food science and technology publications including the Journal of Food Science, Journal of the Science of Food and Agriculture and Molecular Nutrition & Food Research.

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Journal Reference:
Yanyan Wang, Maoquan Li, Xueqing Xu, Min Song, Huansheng Tao, Yun Bai. Green tea epigallocatechin-3-gallate (EGCG) promotes neural progenitor cell proliferation and sonic hedgehog pathway activation during adult hippocampal neurogenesis. Molecular Nutrition & Food Research, 2012; 56 (8): 1292 DOI: 10.1002/mnfr.201200035
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Monday, 12 November 2012

New Findings reveal brain mechanisms at work during sleep

New findings presented today report the important role sleep plays, and the brain mechanisms at work as sleep shapes memory, learning, and behavior. The findings were presented at Neuroscience 2012, the annual meeting of the Society for Neuroscience and the world's largest source of emerging news about brain science and health.

One in five American adults show signs of chronic sleep deprivation, making the condition a widespread public health problem. Sleeplessness is related to health issues such as obesity, cardiovascular problems, and memory problems.



Today's findings show that:
Sleepiness disrupts the coordinated activity of an important network of brain regions; the impaired function of this network is also implicated in Alzheimer's disease (Andrew Ward, abstract 909.05).Sleeplessness plays havoc with communication between the hippocampus, which is vital for memory, and the brain's "default mode network;" the changes may weaken event recollection (Hengyi Rao, PhD, abstract 626.08).In a mouse model, fearful memories can be intentionally weakened during sleep, indicating new possibilities for treatment of post-traumatic stress disorder (Asya Rolls, abstract 807.06).Loss of less than half a night's sleep can impair memory and alter the normal behavior of brain cells (Ted Abel, PhD, abstract 807.13).

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The above story is reprinted from materials provided by Society for Neuroscience.

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Friday, 9 November 2012

Learning requires rhythmical activity

The hippocampus represents an important brain structure for learning. Scientists at the Max Planck Institute of Psychiatry in Munich discovered how it filters electrical neuronal signals through an input and output control, thus regulating learning and memory processes.

Accordingly, effective signal transmission needs so-called theta-frequency impulses of the cerebral cortex. With a frequency of three to eight hertz, these impulses generate waves of electrical activity that propagate through the hippocampus. Impulses of a different frequency evoke no transmission, or only a much weaker one. Moreover, signal transmission in other areas of the brain through long-term potentiation (LTP), which is essential for learning, occurs only when the activity waves take place for a certain while. The scientists even have an explanation for why we are mentally more productive after drinking a cup of coffee or in an acute stress situation: in their experiments, caffeine and the stress hormone corticosterone boosted the activity flow.

When we learn and recall something, we have to concentrate on the relevant information and experience it again and again. Electrophysiological experiments in mice now show why this is the case. Scientists belonging to Matthias Eder´s Research Group measured the transmission of electrical impulses between neurons in the mouse hippocampus. Under the fluorescence microscope, they were able to observe in real time how the neurons forward signals.

Jens Stepan, a junior scientist at the Max Planck Institute of Psychiatry in Munich, stimulated the input region of the hippocampus the first time that specifically theta-frequency stimulations produce an effective impulse transmission across the hippocampal CA3/CA1 region. This finding is very important, as it is known from previous studies that theta-rhythmical neuronal activity in the entorhinal cortex always occurs when new information is taken up in a focused manner. With this finding, the researchers demonstrate that the hippocampus highly selectively reacts to the entorhinal signals. Obviously, it can distinguish important and, thus, potentially recollection-worth information from unimportant one and process it in a physiologically specific manner.

One possible reaction is the formation of the so-called long-term potentiation (LTP) of signal transmission at CA3-CA1 synapses, which is often essential for learning and memory. The present study documents that this CA1-LTP occurs only when the activity waves through the hippocampus take place for a certain time. Translating this to our learning behavior, to commit for instance an image to memory, we should intently view it for a while, as only then we produce the activity waves described long enough to store the image in our brain.

With this study, Matthias Eder and colleagues succeeded in closing a knowledge gap. "Our investigation on neuronal communication via the hippocampal trisynaptic circuit provides us with a new understanding of learning in the living organism. We are the first to show that long-term potentiation depends on the frequency and persistency of incoming sensory signals in the hippocampus," says Matthias Eder.

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Journal Reference:
Jens Stepan, Julien Dine, Thomas Fenzl, Stephanie A. Polta, Gregor von Wolff, Carsten T. Wotjak, Matthias Eder. Entorhinal theta-frequency input to the dentate gyrus trisynaptically evokes hippocampal CA1 LTP. Frontiers in Neural Circuits, 2012; 6 DOI: 10.3389/fncir.2012.00064
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Monday, 5 November 2012

Omega-3 intake heightens working memory

Omega-3 essential fatty acids found in foods like wild fish and grass-fed livestock are necessary for human body functioning, their effects on the working memory of healthy young adults have not been studied until now.

In the first study of its kind, researchers at the University of Pittsburgh have determined that healthy young adults ages 18-25 can improve their working memory even further by increasing their Omega-3 fatty acid intake. Their findings have been published online in PLOS One
.
Led by Rajesh Narendarn, project principal investigator and associate professor of radiology, the Pitt research team sought healthy young men and women from all ethnicities to boost their Omega-3 intake with supplements for six months. They were monitored monthly through phone calls and outpatient procedures.

Before they began taking the supplements, all participants underwent positron emission tomography (PET) imaging, and their blood samples were analyzed. They were then asked to perform a working memory test in which they were shown a series of letters and numbers. The young adults had to keep track of what appeared one, two, and three times prior, known as a simple "n-back test."

After six months of taking Lovaza an Omega-3 supplement approved by the Federal Drug Administration the participants were asked to complete this series of outpatient procedures again. It was during this last stage, during the working memory test and blood sampling, that the improved working memory of this population was revealed.

Although the effects of Omega-3s on young people were a focus, the Pitt team was also hoping to determine the brain mechanism associated with Omega-3 regulation. Previous rodent studies suggested that removing Omega-3 from the diet might reduce dopamine storage (the neurotransmitter associated with mood as well as working memory) and decrease density in the striatal vesicular monoamine transporter type 2 (commonly referred to as VMAT2, a protein associated with decision making). Therefore, the Pitt researchers posited that increasing VMAT2 protein was the mechanism of action that boosted cognitive performance. Unfortunately, PET imaging revealed this was not the case.

"It is really interesting that diets enriched with Omega-3 fatty acid can enhance cognition in highly functional young individuals," said Narendarn. "Nevertheless, it was a bit disappointing that our imaging studies were unable to clarify the mechanisms by which it enhances working memory."

Ongoing animal modeling studies in the Moghaddam lab indicate that brain mechanisms that are affected by Omega-3s may be differently influenced in adolescents and young adults than they are in older adults. With this in mind, the Pitt team will continue to evaluate the effect of Omega-3 fatty acids in this younger population to find the mechanism that improves cognition.

Other Pitt researchers involved in the project include William G. Frankle, professor of psychiatry, and Neal S. Mason, research assistant professor of radiology.

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Journal Reference:
Rajesh Narendran, William G. Frankle, Neale S. Mason, Matthew F. Muldoon, Bita Moghaddam. Improved Working Memory but No Effect on Striatal Vesicular Monoamine Transporter Type 2 after Omega-3 Polyunsaturated Fatty Acid Supplementation. PLoS ONE, 2012; 7 (10): e46832 DOI: 10.1371/journal.pone.0046832
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Thursday, 1 November 2012

Self-directed learning can it be effective?

Educators have come to focus more and more on the importance of lab-based experimentation, hands-on participation, student-led inquiry, and the use of "manipulables" in the classroom. The underlying rationale seems to be that students are better able to learn when they can control the flow of their experience, or when their learning is "self-directed."

While the benefits of self-directed learning are widely acknowledged, the reasons why a sense of control leads to better acquisition of material are poorly understood.

Some researchers have highlighted the motivational component of self-directed learning, arguing that this kind of learning is effective because it makes students more willing and more motivated to learn. But few researchers have examined how self-directed learning might influence cognitive processes, such as those involved in attention and memory.

But we're not always optimal self-directed learners. The many cognitive biases and heuristics that we rely on to help us make decisions can also influence what information we pay attention to and, ultimately, learn.

Gureckis and Markant note that computational models commonly used in machine learning research can provide a framework for studying how people evaluate different sources of information and decide about the information they seek out and attend to. Work in machine learning can also help identify the benefits -- and weaknesses -- of independent exploration and the situations in which such exploration will confer the greatest benefit for learners.

Drawing together research from cognitive and computational perspectives will provide researchers with a better understanding of the processes that underlie self-directed learning and can help bridge the gap between basic cognitive research and applied educational research. Gureckis and Markant hope that this integration will help researchers to develop assistive training methods that can be used to tailor learning experiences that account for the specific demands of the situation and characteristics of the individual learner.

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Journal Reference:
T. M. Gureckis, D. B. Markant. Self-Directed Learning: A Cognitive and Computational Perspective. Perspectives on Psychological Science, 2012; 7 (5): 464 DOI: 10.1177/1745691612454304
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