Mouse Embryo (day 12.5) Stained For Motor (red) And Sensory (magenta) Nerves And Nerve Endings (cyan)

By tracking mRNA scientists can view chemicals within the brain creating memories for the first time. 

(x)

Special brain cells react to unexpected situations

New research from the Netherlands Institute for Neuroscience shows that chandelier cells, a specific type of brain cell, become active during unexpected situations. “Researchers have been wondering about the functionality of these cells for a long time”.

You’re cycling to work through the city and suddenly you see a new building somewhere. On the first day that is very surprising. On day 2 this diminishes somewhat, and after a week you no longer notice it at all. The same thing happens the other way around: when a building that was always there suddenly disappeared, you are also surprised. But how does your brain signal unexpected changes and which cells are involved?

To learn more about this phenomenon, Koen Seignette from Christiaan Levelt’s lab joined forces with his colleagues from the Kole lab and Roelfsema lab. Together, they investigated a special type of brain cell found in small numbers in the cortex: the chandelier cell. In contrast to other inhibitory brain cells, they only inhibit one spot of other cells, but there is remarkably little known about why and when.

New mouse model

Koen Seignette: ‘We already knew quite a lot about the function of most types of inhibitory brain cells, but chandelier cells were a mystery. This is because they are not clearly marked genetically, and so could not be properly examined. We have now obtained a mouse model in which the chandelier cells are fluorescently labeled. This allows us to image them live and determine when they are active. That offers new opportunities.’

‘As a first step, we looked at what chandelier cells in the visual cortex respond to. What happens to these cells when the mouse starts running or when we present visual stimuli? In one of the experiments we had the mice walk in a virtual tunnel. When the mouse ran, the tunnel moved, and when it stopped, so did the tunnel. Using this setup, we could create an unexpected situation by stopping the tunnel while the mouse was still running. It was during these events that the chandelier cells started firing like crazy.’

Plasticity

Christiaan Levelt: ‘We see that the type of stimulus does not actually matter that much, what matters is that it is unexpected and surprising. We also noticed that habituation and change occurs, comparable to the aforementioned example of the new building. At first the cells react strongly, but after repeated exposure the activity becomes weaker. This shows that the cells are able to adapt, which is a concept known as plasticity. This plasticity also occurs at a structural anatomical level: we can literally see changes in the synapses chandelier cells form on other brain cells.’

‘What makes this study important is that this is the first really comprehensive study of chandelier cells in the visual cortex. We have not only determined what they respond to, but also which brain cells they form connections with, and what their influence is on other brain cells. This has never been looked at in such detail before. Understanding the role of these inhibitory neurons in the cortex is crucial for many processes, including learning from unexpected circumstances. We all know that you remember things better when it really surprises you. If the prediction is incorrect, that’s where you can find the information. You need plasticity to update your insights, and these cells could play a role in that.’

Why are chandelier cells so special?

Chandelier cells, named for their resemblance to a chandelier, are inhibitory brain cells that focus on the starting point (axon initial segment) of electrical signals in the pyramidal cells, the most common cells in the cortex. It was thought that chandelier cells could exert strong control over pyramidal cells by blocking the action potential. Surprisingly, the current research shows that this effect is actually very weak, which contradicts previously drawn conclusions.

new booklr accounts :D

I’m looking for some more booklr (bookblr? spelling?) accounts to follow to interact with :D It’s hard to tell how active people are so hopefully some people will want to join in conversation with this!

not now, im noticing the pattern

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1440-1819.2008.01821.x

Cell cultures... pluses and minuses

– You need to come every other day to feed them, otherwise they die or differentiate. – You have to come on weekends too. – If you are not super super careful, some bacteria or yeast will eat them up. – Even if you are super super careful, some bacteria or yeast will sometimes eat them up. – In experiments, there are huge differences in the behavior of cells so you will have huge errors and have to repeat the experiments multiple times to prove your point.

+ You have to do it, so your other studies are tested on something alive and thus are proved relevant.

That's it. Nothing else to the + list. Cells are bitches. You have to nurture them and pamper them and sacrifice weekends, and then they die or behave unpredictably.

feeling very normal about this

Cosmic clouds form fantastic shapes in the central regions of emission nebula IC 1805. The clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula's newborn star cluster, Melotte 15. IC 1805 is located about 7,500 light years away toward the boastful constellation Cassiopeia.

Image Credit: Richard McInnis

cognoscit