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June 27, 2011, 5:26 pm

How worms help us to explain brains!

Tiny worms seem unlikely helpers in our search to try to understand how brains work... but neuroscientist Cori Bargmann knows exactly what questions to ask and what techniques to use to let worms reveal their secrets!

What was discovered?

The lab worm called Caenorhabditis elegans is only about 1mm long, but it can smell out good sources of food using protein receptor molecules in its olfactory (smell sense) organs.

Remarkably, the worms have over 2,000 genes to control making these receptor proteins - more than double the number found in rats!  Why?  [think of where we find worms... dark, underground places where sight is not very good for finding food, but smell is!]

Dr. Bargmann has found exactly which receptor proteins can "smell" certain chemicals, and how the brain of the worm interprets the presence of the chemical on the receptor proteins.

How?

This is where the tools of genetics are very useful... mutant worms can be made which can no longer smell certain chemicals because the gene controlling the particular protein receptor is turned off.

This sounds simple - linking a mutant gene with a protein receptor that no longer works - but it takes a very long time to make the right mutants and to look down a microscope to observe what is happening in each mutant - can the worm still smell the chemical or not?

And how do you see if a neurone is working or not?  This is where scientific creativity is needed... in this case to make mutants where active neurones will glow bright green if they are working!  Cool, and pretty!

Why is it important?

Worms have much smaller brains than humans, yet the ways that the 302 neurones (nerve cells) connect and communicate using synapses is similar, and this has been "mapped" for worms.

But the neurones also connect using chemicals that can "leak" through holes between cells called gap juntions. This communication has also been mapped, and it is different to the synapse pattern!

What's even more amazing is that other chemicals, called neuropeptides, can change the connections in either of the above networks... changing the brain's "mood"!

So if we can start to understand how a worm brain works, we will have a greater insight into how our brain works too... 

many thanks to neuroscientist Cori Bargmann, who was a speaker at the Molecular Frontiers Symposium in Stockholm in 2009 (see her in the photo albums in Forum Live!).

 

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