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Northwestern University: Embargoed for release: 21-Nov-2007 12:00 Eastern US Time


Molecular foreman in the brain

Scientists have found a master molecule in the brain. It runs the show when connections between brain cells are being remodelled - which is how we learn new information and skills.


When the mechanism the scientists have found goes wrong the result may be mental retardation, schizophrenia or drug addiction. So this new discovery could improve our understanding of these disorders of the brain.


Peter Penzes and his colleagues published their findings in the November 21, 2007, issue of the journal Neuron, published by Cell Press.


Brain cells are known as neurons by scientists. In these new experiments, the researchers tried to understand what controls the growth of dendritic spines on neurons. These are the receiving stations for signals sent from nearby brain cells.


When a brain is learning, signalling between these spines increases. This lays down memories in the brain. Spines can also play a part in brain disorders. Badly formed dendritic spines have been found in autistic spectrum disorders, schizophrenia, ADHD and drug addiction.


Penzes and his colleagues were trying to discover if a molecule called kalirin-7 plays a role in spine growth in mature neurons during long-term potentiation (LTP).


Their theory was that kalirin-7 regulates the growth of the spines. Evidence for this is its high concentration in the spines of mature neurons. Also kalirin-7 was known to play a role in the remodelling of the overall structure of the cell - the cytoskeleton.


The researchers carried out their experiments with neurons in culture. These showed that activation of neurons during long-term potentiation does indeed trigger kalirin-7 to turn on the machinery for remodelling the spines. This makes them grow larger.


They also found that kalirin-7 regulates the other main process that strengthens signalling between neurons. It controls the number of receptors. These are found all over the surface of dendritic spines. They act as receiving stations for neurotransmitters.


The strength of signalling between neurons depends on the number of receptors they have on them.


These new findings, say Perez and his colleagues, strongly suggest that kalirin-7 plays “an important role in learning and memory.”


They also point out that altered spine structures “have been associated with mental retardation, neuropsychiatric disorders, and drug addiction.


“Therefore, our results may suggest potential strategies for treatments of these neurodevelopmental and psychiatric diseases,” they write.


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What's it all about?

  1. In which part of the body have scientists have found an important molecule?
  2. The writer calls this molecule a 'foreman' because it ---- --- ----.
  3. This molecule is active when we are doing what?
  4. State two things that might happen to a person if things go wrong with this molecule.
  5. What is a neuron?
  6. The experiments were set up to help the scientists understand what?
  7. What is a dendritic spine?
  8. When you are learning new things what happens to the signals between the dendritic spines in your brain?
  9. Were the scientists looking at young neurons or neurons that had been around for a while?
  10. What word gave you the answer to the last question?
  11. Two facts made the scientists think that kalirin-7 might have something to do with the growth of the spines. State one of these.
  12. Did the scientists study neurons inside somebody's brain?
  13. Where did they study them?
  14. They found that kalirin-7 had two jobs to do when long term memories were being formed. State one of these.
  15. As well as increasing our understanding of how memories are made, what other applications might there be for this new discovery?
  16. If you were these scientists what questions would you still have about what this chemical does?
  17. Briefly outline an experiment that might help you to answer that question.


More learning and teaching resources

University of Washington Television has an online video of a teacher/scientist introducing youngsters to the workings of the brain. Show the class the section on neurons and how they communicate with each other that starts 8 minutes 15 seconds in and lasts just over 4 minutes.


Then invite students, working in groups, to use what they have just seen and heard, and what they have learned from the links to this article, to sketch the three brain cells in the video demonstration.


They should label the different parts of each cell and draw arrows to show the direction of a signal - along the different parts of a cell and from one cell to another.


For groups that need a hand to get started, you can tell them that the following parts should be shown in their diagram:



And the arrows for the signals should be labelled either 'electrical signal' or 'chemical signal'.


Once the diagrams have been sketched, groups should give a short explanation or demonstration to the class.


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