Grooming only half side of the body

Grooming only half side of the body. Credit: http://www.bajiroo.com/2013/04/23-guys-with-half-shaved-beard/
Grooming only half side of the body. Credit: http://www.bajiroo.com/2013/04/23-guys-with-half-shaved-beard/

Contrary to popular belief, rats and mice are very fastidious animals; they keep themselves scrupulously clean by engaging in a very meticulous routine of self-grooming. The routine is so rigorous that allows the researchers to divide the grooming sequence into four different phases, starting with the nose and whiskers and ending with the genitalia and tail. It is also a symmetrical behavior (no whisker left ungroomed, no paw unlicked).

Grooming is sensitive to dopaminergic manipulations, so Pelosi, Girault, & Hervé (2015) sought to see what happens if they destroy the dopamine fibers in the mouse brain. So they lesioned the medial forebrain bundle, which is a bunch axon fibers that contains over 80% of the midbrain dopaminergic axons. But they were tricky, they lesioned only one side.

And the results were that the lesioned mice not only exhibited less self-grooming on the opposite side to the lesion, but the behavior was rescued by L-DOPA, which is medication for Parkinson’s. That is, they gave the mice some L-DOPA and they began to merrily self-groom again on both sides of the body. The authors discuss in depths other findings, like the changes (or absence thereof) in grooming bouts, grooming time, grooming bouts, completeness of grooming etc.

The findings have significance in the Parkinson’s research, where the mild to moderate phases of the disease often present with asymmetrical motor behavior.

Reference: Pelosi A, Girault J-A, & Hervé D (23 Sept 2015). Unilateral Lesion of Dopamine Neurons Induces Grooming Asymmetry in the Mouse. PLoS One. 2015; 10(9): e0137185. doi: 10.1371/journal.pone.0137185. PMCID: PMC4580614. Article | FREE FULLTEXT PDF

By Neuronicus, 29 October 2015

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Making new neurons from glia. Fully functional, too!

NeuroD1 transforms glial cells into neurons. Summary of the first portion of the Guo et al. (2014) paper.
Fig. 1. NeuroD1 transforms glial cells into neurons. Summary of the first portion of the Guo et al. (2014) paper.

Far more numerous than the neurons, the glial cells have many roles in the brain, one of which is protecting an injury site from being infected. In doing so, they fill up the injury space, but they also prohibit other neurons to grow there.

Guo et al. (2015) managed to turn these glial cells into neurons. Functioning neurons, that is, fully integrated within the rest of the brain network! They did it in a mouse model of stab injury and a mouse model of Alzeihmer’s in vivo. Because a mouse is not a man, they also metamorphosized human astrocytes into functioning glutamatergic neurons in a Petri dish, that is in vitro.

It is an elegant paper that crossed all the Ts and dotted all the Is. They went to a lot of double checking in different ways (see Fig. 1) to make sure their fantastic claim is for real (this kind of double, triple, quadruple checking is what gets a paper into the Big Name journals, like Cell). Needles to say, the findings show a tremendous therapeutic potential for people with central nervous system injuries, like paralyses, strokes, Alzheimer’s, Parkinson’s, Huntington, tumor resections, and many many more. Certainly worth a read!

Reference: Guo Z, Zhang L, Wu Z, Chen Y, Wang F, & Chen G (6 Feb 2014, Epub 19 Dec 2013). In vivo direct reprogramming of reactive glial cells into functional neurons after brain injury and in an Alzheimer’s disease model. Cell Stem Cell, 14(2):188-202. doi: 10.1016/j.stem.2013.12.001. Article | FREE FULLTEXT PDF | Cell cover

By Neuronicus, 18 October 2015

Wireless mice, batteries not included (optrodes and electrodes in one wireless contraption)

A neuron is expressing the light-gated cation channel channelrhodopsin-2 (small green shapes), and is being illuminated by a focused beam of blue light (coming from the top). The opsins have opened, depolarizing or electrically activating the cell. The pulse of electricity spreads throughout the inside of the cell (white highlights), triggering the release of neurotransmitters to downstream cells. Credit: Ed Boyden and Massachusetts Institute of Technology McGovern Institute Courtesy: National Science Foundation
A neuron is expressing the light-gated cation channel channelrhodopsin-2 (small green shapes), and is being illuminated by a focused beam of blue light (coming from the top). The opsins have opened, depolarizing or electrically activating the cell. The pulse of electricity spreads throughout the inside of the cell (white highlights), triggering the release of neurotransmitters to downstream cells. Credit: Ed Boyden and Massachusetts Institute of Technology McGovern Institute. Courtesy: National Science Foundation

Optogenetics is the new (and very popular) kid on the block of neurotechniques arsenal. Before optogenetics, in order to manipulate how the neurons behave in a particular brain region, one had to do so electrically or chemically by inserting into that region an electrode or a tube, respectively. The trouble with that is that you never know exactly which neurons you are manipulating, given that any brain regions has many kinds of cells that project to many other regions and they are not nicely arranged in clumps but interspersed in a messy mesh. But with optogenetics, you can select exactly which neurons you want to manipulate. You take a mouse and you genetically engineer it to express in your favorite neurons a particular protein that is sensitive to a certain light wavelength (like a rhodopsin). Then, you shine the light in the mouse’s brain, turning on and off the neurons of your interest. The technique, besides having tremendous success in fundamental research, also shows promise for neuroprosthetics for some diseases, like Parkinson’s.

Despite rapid improvements of the technique due to increasing demand form the neuroscience community, it is still difficult to record from the freely-moving animal, mainly because the animal is attached to the fiber optic that delivers the light pulses. There have been some wireless attempts (some successful), but because the resultant contraption was too big and heavy for the animal, they have reduced options as compared to the wired devices. Gagnon-Turcotte et al. (2015) describe here a way to build a wireless headtsage that can deliver light pulses AND record the electrophysiological activity of the neurons. And, equally important, is cheap and can be build with off-the-shelf components.

Reference: Gagnon-Turcotte, G., Kisomi, A. A., Ameli, R., Camaro, C.-O. D., LeChasseur, Y., Néron, J.-L., , Bareil, P. B., Fortier, P., Bories, C., de Koninck, Y., & Gosselin, B. (9 September 2015). A Wireless Optogenetic Headstage with Multichannel Electrophysiological Recording Capability. Sensors, 15(9): 22776-22797; doi:10.3390/s150922776. Article + FREE PDF

By Neuronicus, 22 September 2015

Update (27 September 2015). The author Gabriel Gagnon-Turcotte wins the Mitacs 2015 prize for exceptional innovation for the development of a wireless system to study the brain