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My lab:
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I've recently been invited to
attend the EPS Hohhot International Paediatric Conference 2011, which will be held during August 3-5, 2011 in Hohhot, Inner Mongolia, China. We would like to welcome you to our Conference as our valuable speaker and present your recent work and ideas of Mushroom bodies regulate habit formation in Drosophila. that were published in Curr Biol. Please visit our website at www.epsglobal.ca & www.epsworldlink.com/en for program details.
It's pretty clear that inviting a fly-guy to a conference is rather unlikely. A quick online search verified that this conference was, in fact, a spam-ference.

Right now, I'm in Ashburn, Virginia, at a real conference hosted by HHMI's Janelia Farm. We will be talking about the differences and commonalities between honeybees and fruit flies in how their brains store memories: “Learning and Memory: A Synthesis of Flies and Honeybees”. After a reception and dinner, the conference was kicked off at 8.15pm by Randolf Menzel talking about the most prominent brain structure of all insects, the mushroom-bodies.

Randolf Menzel provided a brief recapitulation of the history of the study of the mushroom-bodies starting with Dujardin in the mid-19th century, Kenyon at the turn of the century, Flögel in the early 20th century and then the many anatomists in the late 20th century such as Mobbs, Strausfeld, Rybak et al., some of which are still active today. In honor of Kenyon, the intrinsic neurons of the mushroom-bodies were called Kenyon cells in the 1970s..

In many insects, the mushroom-bodies are organized according to the sensory input they receive, such that particular regions of the calyces receive olfactory or visual input, respectively. The mushroom-bodies were hypothesized throughout the 90th century to be involved in insect 'intelligence' as animals with a richer social life also appeared to sport larger mushroom-bodies. This general idea has in principle been supported by more recent research. Recently, it has been suggested that the evolutionary ancestry of hymenopterans a parasites, via the complicated host-finding behavior, has led to highly evolved mushroom-bodies allowing for the later evolution of social behavior.

Menzel then transitioned back to the anatomy, by asking why the Kenyon cells are branching into the different lobes of the mushroom-bodies. In the mid-20th century it was suggested that these neurons act as pre-motor neurons with one of the branches providing a feedback loop back to the Kenyon-cell input regions. Another speculation at the time was that the Kenyon-cells function as oscillators (via feeback loops enabled by the branching).

In the second part of the 19th century, people started to test these hypotheses experimentally. huber stimulated different regions of the mushroom-bodies and found that some regions inhibited stridulation in crickets and other activated singing behavior. Later experiments suggested the mushroom-bodies function as memory storage.Masuhr, in Menzel's lab, cooled various parts of the honeybee brain and found that retrograde amnesia of odor-memories (after classical conditioning) was induced when the mushroom-bodies were cooled. More recently still, neurogenetic experiments with Drosophila supported the notion that 'elementary forms of memory' are stored in the Kenyon-cells.

Later anatomical studies discovered that Kenyon cells can be sub-divided into different populations of neurons (e.g. clawed Kenyon-cells and others). Clawed Kenyon-cells form 'micro-glomeruli' with the synapses of the projection neurons coming from the antennal lobes and transmitting olfactory information to the mushroom-bodies.

Current models of mushroom-body function emphasize sparse coding in the Kenyon-cells, preventing anything but coincident input to bring these neurons to fire. This organization allows for a large number of memories to be stored in the mushroom-body network.

Interestingly, the output neurons of the mushroom-body alpha lobe are extremely promiscuous in that they fire regardless of the sensory modality and are generally very unspecific in their asctivity profiles. Some of these extrinsic neurons in the alpha lobe also fire during particular sleep phases in honey bees, but most of them show reduced activity during sleep. Sleep deprivation impairs extinction memory after olfactory classical conditioning and impairs navigation in honey bees.

In the end, Menzel entertainingly speculated about 'what the bee might be telling the fly about the mushroom-bodies?'.
Posted on Monday 16 May 2011 - 03:27:08 comment: 0
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