Neuroscience posts from Today
- February 13, 2012
- 08:19 AM
- 5 views
Neurons tuned like the strings of a harp
by TheCellularScale in The Cellular Scale
The auditory brainstem of the boring-old-chicken is actually home to some fascinating neurons.Key West rooster, taken by me.The Nucleus Laminaris (NL) is a group of coincidence-detecting neurons which receive indirect input from both ears and is located in the bird auditory brainstem. NL neurons show a peculiar dendrite pattern. These bipolar neurons fall into the particular category of football shaped cells which have dendrites coming out the top and bottom of their cell body. The cell body (soma) of these neurons are about the same size, but depending on where they are in the NL, the cells have either short, medium or long dendrites. The ones near the midline have a bunch of short stubby little dendrites.Figure 2B from Smith and Rubel, 1979If they are a little further out from the midline, they have longer dendrites.Figure 3B from Smith and Rubel, 1979and finally if they are furthest from the middle, they have fewer and much longer dendrites.Figure 10A Smith and Rubel 1979all together this makes a gradient from short to long dendrites. From Figure6 Smith and Rubel 1979The big question here is "Why?"What is the purpose of having stubby or extended dendrites like this? Well, even in 1979 when Smith and Rubel reconstructed these neurons, they knew that these neurons had a special answer to the "form and function" question. The amazing thing about these neurons is that they are 'tuned' to respond maximally to specific frequencies (sound waves). And just like strings on an instrument, the cells with shorter dendrites respond to higher frequencies and the cells with longer dendrites respond to lower frequencies. Why is this? Dendrites don't actually vibrate like strings, but there must be some reason for a cell with short dendrites to respond to higher frquencies and a cell with long dendrites to respond to low frequencies. The answer lies in what the Nucleus Laminaris actually does. In the next post we'll venture into the wilds of computational neuroscience and explore the reason behind this strange connection between dendrite shape and cell function. © TheCellularScaleSmith DJ, & Rubel EW (1979). Organization and development of brain stem auditory nuclei of the chicken: dendritic gradients in nucleus laminaris. The Journal of comparative neurology, 186 (2), 213-39 PMID: 447882... Read more »
Smith DJ, & Rubel EW. (1979) Organization and development of brain stem auditory nuclei of the chicken: dendritic gradients in nucleus laminaris. The Journal of comparative neurology, 186(2), 213-39. PMID: 447882
- February 13, 2012
- 07:00 AM
- 5 views
February 13, 2012
by Erin Campbell in HighMag Blog
Our nervous system would be in trouble without myelin sheaths and nodes of Ranvier. No, those two things do not refer to some kind of Lord of the Rings-type silliness. They are very important components of our nervous system that ensure fast and efficient signal conduction.Myelin sheaths are membranes that insulate the axons of many neurons. Myelin sheaths have distinct domains of ion channels and proteins, such as the nodes of Ranvier, along the axon that are required for the high speed and efficiency of signal conduction along the axon. The nodes of Ranvier, for example, are especially important for swift movement of an axon’s action potential, which jumps from node to node in a process termed staltatory conduction. A recent paper describes the importance of a cytoskeletal adaptor protein called 4.1G in regulating the localization of proteins along the axon-sheath interface. Ivanovic and colleagues found that in mice without 4.1G, adhesion proteins and neuronal proteins were mislocalized. Images above show localization of 4.1G at the same sites as two other periaxonal membrane proteins (MAG on left, Necl4 on right) in adult mouse sciatic nerves.Ivanovic, A., Horresh, I., Golan, N., Spiegel, I., Sabanay, H., Frechter, S., Ohno, S., Terada, N., Mobius, W., Rosenbluth, J., Brose, N., & Peles, E. (2012). The cytoskeletal adapter protein 4.1G organizes the internodes in peripheral myelinated nerves originally published in the Journal of Cell Biology, 196 (3), 337-344 DOI: 10.1083/jcb.201111127... Read more »
Ivanovic, A., Horresh, I., Golan, N., Spiegel, I., Sabanay, H., Frechter, S., Ohno, S., Terada, N., Mobius, W., Rosenbluth, J.... (2012) The cytoskeletal adapter protein 4.1G organizes the internodes in peripheral myelinated nerves. originally published in the Journal of Cell Biology, 196(3), 337-344. DOI: 10.1083/jcb.201111127
- February 13, 2012
- 12:12 AM
- 24 views
Just ONE Copy of The Daily Mail Could Ruin Your Life
by Neurobonkers in Neurobonkers
A comprehensive debunking of the Daily Mail's reporting of science.... Read more »
The Poynter Institute. (2006) Eyetracking the news. A study of print and online reading. Poynter. info:/
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