Science News

A Researchers Pick of Neuroscience News

Sun, 20th Jan 2013

Hannah Critchlow, David Weston

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It’s time to take a look at the top stories from this month, I join PhD student David Weston from Cambridge University. He’s been busy shifting through neuroscience research and comes up with his three favourite papers from the month....

David - So the first paper I would like to talk about has to do with memory. Now scientists have long thought that the birth of new brain cells within an area of the brain called the hippocampus, is really important for memory function. But exactly how these new brain cells work and how they integrate into the brain is something that researchers having been working hard over. Now a group of scientists based at the State University of New York in the USA have used a combination of viral and optogenetic techniques to find out just how important the growth of new brain cells within the hippocampus really is.

Hannah - So these scientists want to find out why these Nerve Cellnew-born cells are so important. How did they go about finding more about these cells?

David - Well they used a virus to deliver light-sensitive genes into new-born cells within the hippocampi of adult mice. Now this virus infects only the new-born cells and gives them these genes that produce proteins sensitive to light. The researchers were then able to control these cells by shining lights of different colours onto the cells to activate or deactivate them.

Hannah - So just by shining different coloured lights they could control whether these new-born cells were activated or deactivated. What did they do next?

David - Well what they wanted to do was see how important new cells within the hippocampus are for memory function. So first they showed that if they activated these new-born cells they could enhance synaptic plasticity, which is widely believed to correlate with better memory function. They then tried deactivating these cells and they found that the mice performed much worse is some tests of memory function.

Hannah - So the new-born cells definitely had something to do with memory formation.

David - Yes, but interestingly the effects of manipulating the new-born cells were only seen when the cells were 4 weeks of age, not when they were older or younger. These results hint at the idea that new cells within the hippocampus are able to exert their memory-enhancing effects only at early stages of their development.

Hannah - So this means that the timing of when new cells are born could play an important role in memory function and behaviour. Fascinating! What’s your next paper?

David - The second paper I want to talk about also has something to do with timing. It’s about how much of your life is affected by your time as a foetus. There is an increasing amount of evidence suggesting that many aspects of your adult health can be traced back to your aspects of your foetal environment and importantly your birth weight.

Hannah - So your weight at the time of you birth might be linked to things to do with your brain? How did the scientists in the study work that out?

BrainsDavid - So this group of scientists working across both Norway and the USA collected data from 628 adults, adolescents and children, measuring things like the thickness of their cerebral cortex, their brain volume and the surface area of their brain using scans taken in an MRI machine. They found that as birth weight increased the total brain size as an adult was much larger.

Hannah - So birth weight influences brain size, but why is this important?

David - Well low birth weight can influence your likelihood of getting some cognitive disorder such as autism, where you are five times more likely to get the disease. And while this study doesn’t make any specific links between birth weight and disease it does show that brain development is heavily influenced by factors surrounding your birth.

Hannah - What’s your final paper?

David - So the final paper this time is about a new drug that could help fight the effects of Alzheimer’s disease. A collaboration between groups in Japan and Canada have taken an anti-diabetes drug and tested its ability to reverse some of the deleterious effects of the disease.

Hannah - How can a drug designed for diabetes treatment help with Alzheimer’s Disease?

David - Well this drug, AC253, was originally part of a drug trial looking for potential targets for diabetes.  One of these targets is the amylin protein, which is similar to the toxic amyloid protein, that builds up in the brain and is a key target for Alzheimer’s Disease.  This team had already shown that AC253 could block the formation of toxic amyloid protein and in this paper they showed that treating brain cells with this drug could reverse some of the effects of Alzheimer’s.

Hannah - So these experiments were performed on cells in petri dishes, but how close could this be to a treatment for Alzheimer’s disease in humans?

David - Well the authors themselves seemed quite optimistic about the prospect for a drug treatment. These results are encouraging because they show a reversal of Alzheimer’s effects, which might mean things like being able to reverse a loss of memory!

Optical controlling reveals time-dependent roles for adult-born dentate granule cells. Gu et al. (2012) Nature Neuroscience, 15 1700-1706

Long-term influence of normal variation in neonatal characteristics on human brain development. Walhovd et al. (2012) PNAS 109 (49) 20089-20094

Beta Amyloid-Induced Depression of Hippocampal Long-Term Potentiation Is Mediated through the Amylin Receptor. Kimura et al. (2012). Journal of Neuroscience. 32 (48) 17401-6.

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