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Archive for the category “Neuroscience”

Synapses and actin.

Jon Hanley (Bristol): Actin dynamics in dendritic spines (Neural Dynamics Forum, 16/3/2012).

So there were lots of details in this interesting talk and lots of pictures of glowing dendritic spines; the basic topic was the changes that occur in dendritic spines during long term plasticity and the role actin plays. One thing I learned was that there are two processes at work in long term plasticity, a relatively quick one in which receptors are removed and sequestered away from the membrane and a slower one in which the spine itself changes size. Since, to the first approximation, the strength of the synapse depends on the number of receptors, the first process is sufficient to effect the plasticity: it would be interesting to know if the plasticity is somehow more provisional, more reversible, before the spine changes size and consolidates the change, I asked about this but it isn’t known. The spines themselves are not as button shaped as I expected, they are more like mushrooms, with a neck and a blob; the actin are long proteins that seem to lie along the inside of the spine and are continually being build and broken apart.

Zebra Finch song.

Most of the data I use is recorded from the neurons in Zebra finch, an Australian song bird often used as a model animal for learning. The particular value of using song bird in studying primary processing of sensory information is that a corpus of songs from the same species is considered a good proxy for the natural acoustic environment. It is important to use natural stimuli, neuronal processing is likely to be tuned to natural stimuli and processing is likely to exploit the statistical structure of the environment. However, what is meant by natural is hard to define, we get away with not thinking about this by pretending a collection of bird songs will do, this isn’t proved, but it is plausible.

Anyway, above is a recording of a Zebra finch singing, first a series of squawks, announcing the song, then the song itself.

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