Author Topic: Question about authenticity of hell theough tesiminy, main part of question bold  (Read 934 times)

Asmodean

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You got me there, I have no idea.  :(  I'm guessing that it's not the case that there's absolutely no contamination.
Hey, that's a perfectly legitimate answer.

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However, when compared to the pharmacological approach, in which you basically inject a drug into the desired area of the brain, it will act on many, many cells in that region, even ones that wouldn't have been recruited anyway. Even so, you can still see behavioural effects that indicate more or less what is likely happening. Problem is there are compensatory netowrks that also come into play, but I won't ramble on about that...
Yes. This, I think, is very much onto what I was talking about. I think it's like... Obviously, there are ways of analysis, which help you distinguish the signal, I suppose, from the population of cells you want from the background clutter of those you do not. I suspect, though, that that could be harder to filter out if observing things like behavioural differences? What was caused by what you were trying to demonstrate, and what by the mode and magnitude of spread of chemical agents introduced to the brain?

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So, in comparison, optogenetics and even chemogenetics (DREADDs - you might like that name  ;D) are far "cleaner" than the pharmacological approach.

Pharmacology is what I have to work with, but I dream of an opportunity to possibly spend some time in a lab with money to spare and has the whole optogenetic toolkit at their disposal. :tellmemore:
Yes, I do like the name. I hope you do get the opportunity to work with optogenetics, and when you do, I hope you tell us. With pictures. :tellmemore:

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Yes, there are loads of physiological differences between neurons that are activated, and at different time points too. For instance, the Early Immediate Genes I mentioned earlier result in proteins that are expressed by only the neurons that were recruited. We can see those too, using immunohistology techniques. One such gene is FOS, which encodes for the c-fos protein.

This is a section of a rat hippocampus (proportionally larger than ours). 8) The red/orangy cells are ones which were last recruited during a behavioural task, which express the early immediate gene protein, c-fos. The green dots are neurons and blue dots are the nuclei of neurons and glial cells.

I could stare at that image all day.  :tellmemore:
This is totally awesome! Does each "light" represent a single cell? I mean... The resolution of it, with regard to what you are trying to see... Amazing. In my mind, it conjures up a neuroscience parallel to the Hubble Deep Field image.

I see the orange-y cells are kind of spread apart. Is that meaningful? Or are they actually more or less directly connected with each other?

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;D Funnily enough, that was the debate/argument that Golgi and Ramón y Cajal ("father of neuroscience") had at the turn of the 20th century. Golgi believed that everything was continuous while Cajal said that cells were discrete units, not continuously joined. Cajal was right, but both were awarded the Nobel prize.

https://en.wikipedia.org/wiki/Reticular_theory

 :o Ah, I had to list the distinction between two types of synapse in the entry exam for my master's...let's see if I can still remember:

There are two types of synapses, electrical, which are in physical contact with eachother and there are no neurotransmitters, and chemical, in which there is a cleft between them and neurotransmitters are necessary to get the signal across. In invertebrates, synapses are mostly electrical whereas in vertebrates they're mostly chemical. Electrical synapses are bidirectional whereas chemical synapses go only in one direction, from the presynaptic neuron to the postsynaptic neuron, though there are the so-called 'atypical neurotransmitters', such as endocannabinoids that go in the inverse direction (yes, our systems produce cannabinoids  ;D ).

What else...

Electrical synapses are faster than chemical ones. But if they're faster, then why have chemical synapses in the first place, and why do 'more evolved' animals such as vertebrates have more chemical synapses? One answer is that chemical synapses are regulated. They're more complex, but there are more 'steps' along the way that can be inhibited, facilitated or modulated, resulting in a larger behavioural repertoire.   
So... The electrical synapses do indeed pass current from one to another, sort of like a compound wire, made up of individual strands of conducting material, while the chemical ones are passing signal, typically one way, through the use of chemical compounds... I get it!  :) Without going into evolutionary biology, are there good and valid reasons for this unidirectionality? The engineer in me does see the need for an occasional unidirectional valve, but overall, is it not... Limiting, even though you can "regulate the flow?" Or do such connections come in pairs/clusters so that two cells can both send and receive signal to and from each other? Or... How is that facilitated, especially considering that chemical synapses are dominant in complex creatures? Do some systems only need to "send orders" without real need for feedback? How do they know, then, what orders to send? Where be the loop, to put it crudely?

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As for the ratties, yes, they are heroic. One of my labmates even added them in the acknowledgement part of his thesis. I thought that was awesome.
That person is going straight into The Evil God's Good Book. :D

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While animal experimentation is a controversial topic (my family, for instance, does not approve), all experiments have to be approved by an ethics committee made up of people from many backgrounds before they can be done. You have to be rigorous in your justification for using animals before you can use them. That's why scientists have to be 'salespeople' as well, you have to 'sell' your idea to others all the time. 
I get it. And I approve of ethical treatment of animals in lab conditions. Like ratties as I might, I am not opposed to animal experiments as a matter of principle. In order to further knowledge, some times there really is no other way... And sometimes those animals pay a heavy price for science, but... They save and prolong lives, teach us about ourselves and the world we inhabit, contribute to the increased health and productiveness of human societies, and acknowledging that, while doing your best to respect life - to not throw it away without a damned good reason and a well thought-through justification, well, it goes a long way with me.

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Memories tend to become more generalised when they become more dependent on cortical structures. They lose detail, and become more 'semantic'. This means that they do lose some precision, and some researchers have proposed it is a form of forgetting, but I think not. Generalisation is not the same as forgetting.

Implanting memories?  :unsure: I don't think it's theoretically possible to 100% transfer a memory because everyone's brain in different in their connections, memories are coloured by perception as well, and attention...I don't know. I'll have to look into that. It would be cool if it were possible, though! :grin:
I can see why some would consider generalising a form of forgetting, because it appeals to my colloquial sense. You had a detailed image before, and now you don't, so you forgot the details. That's almost certainly not that simple "in the business," though. It's interesting... I personally liken forgetting to a search index failure. You have a database with an entry, which is no longer indexed. The information still exists, you just... Can't access it in any meaningful way, because the only way to do a search is index-dependent. It's not a perfect comparison, but it's driven by the observation that long-forgotten memories can re-surface, given the correct circumstances.

Do scientists also understand forgetting in this general neighbourhood, or is it a tiered system of sorts, or does it refer to memories being permanently... "Erased?"

Hmm... Yes, I suppose a perfect memory transplant would be a stretch. I was wondering more about transplanting something very simple, what requires comparatively few resources. It may still be a daunting task, but imagine what being able to compare an original memory to an implanted one could tell us! That would indeed be vastly cool.

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:thumbsup:
:headscratch: Yes, there are questions. I thinks the next round, I'll start delving a little bit into the Trace Transformation Theory :)
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xSilverPhinx

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I'll have to get back to you after Tuesday. :grin: I've gone and done it again, procrastinated until almost the last moment, and now I'm paying the price. :(
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Asmodean

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I can relate; did it last week ;)
In Asmo's grey lump,
wrath and dark clouds gather force.
Luxembourg trembles.