A single memory is stored across many connected brain regions
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Re: A single memory is stored across many connected brain regions
#2I've never really loved contextual fear conditioning as the default for "memory". Another way of describing this result is that "even a mild trauma scars the entire brain."
In all seriousness, though, I'd say that there's a broad dispute in the field between those that believe that memory involves dynamic neural activity involving a multiplexed circuit of neurons that encode many different memories and those (currently led by the Tonegawa lab) that think that memories are associated with individual neurons.
Re: A single memory is stored across many connected brain regions
#3I've never really loved contextual fear conditioning as the default for "memory". Another way of describing this result is that "even a mild trauma scars the entire brain." In all seriousness, though, I'd say that there's a broad dispute in the field between those that believe that memory involves dynamic neural activity involving a multiplexed circuit of neurons that encode many different memories and those (current…
Do we actually know how the memory is coded specifically? Is it a specific firing of a neuron (or a neuron ensemble), is it the specific answer you get from exciting the neuron(s)? Or any combination thereof?
Re: A single memory is stored across many connected brain regions
#4Disclaimer: I know brain != deep learning neural nets. We do have a lot of evidence that the brain is _some_ type of network with analogue qualities.
Does it even make sense to say that a memory is stored somewhere in a specific region, if the brain is an analogue network? A property of analogue networks is that all nodes make a contribution, even if many of the contributions are infinitesimally small. The equivalent for deep learning is that information is stored in the weights and any given output is a function of all the weights. Some weights are more important than others in producing the output, but the point still stands.
Re: A single memory is stored across many connected brain regions
#5I've never really loved contextual fear conditioning as the default for "memory". Another way of describing this result is that "even a mild trauma scars the entire brain." In all seriousness, though, I'd say that there's a broad dispute in the field between those that believe that memory involves dynamic neural activity involving a multiplexed circuit of neurons that encode many different memories and those (current…
Do we actually know how the memory is coded specifically? Is it a specific firing of a neuron (or a neuron ensemble), is it the specific answer you get from exciting the neuron(s)? Or any combination thereof?
> Do we actually know how the memory is coded specifically?
No, we don't.
Re: A single memory is stored across many connected brain regions
#6Their paper assume in the premise the conclusion..
All depend on the accuracy of their fluorescent genetic memory correlate. It's not because this genetic marker is necessary for memory encoding that it is parcimonious and only affect memory encoded region.
An in depth presentation of the properties of the gene would solidify or weaken their findings, as for now since I'm lazy, I will suspend my judgment.
Re: A single memory is stored across many connected brain regions
#7Disclaimer: I know brain != deep learning neural nets. We do have a lot of evidence that the brain is _some_ type of network with analogue qualities. Does it even make sense to say that a memory is stored somewhere in a specific region, if the brain is an analogue network? A property of analogue networks is that all nodes make a contribution, even if many of the contributions are infinitesimally small. The equivalent…
If I take pretrained imagenet and just make it wider with nodes with random weights and biases, I can still feed the network an image and get a reasonably correct label as an output. In this example I could obviously point at the nodes from the original imagenet and say that those do the image recognition, we know the rest of the network doesn't contribute anything but noise.
On a technical level of course the whole network contributed to the output. In everyday reasoning and language however we usually focus on the parts that matter to a reasonable degree and ignore the rest. A sack of rice falling over in 2005 might have contributed to the 2008 financial crisis. With the world being an analog network of particles it even seems obvious that that sack of rice must have had some infinitesimal influence one way or the other, it's just more practical to ignore it.
Re: A single memory is stored across many connected brain regions
#8Earlier quoted context omitted.
Do we actually know how the memory is coded specifically? Is it a specific firing of a neuron (or a neuron ensemble), is it the specific answer you get from exciting the neuron(s)? Or any combination thereof?
> Do we actually know how the memory is coded specifically? No, we don't.
Man I wish I became a neuroscientist or something. Seems like there’s so much work to do in that field if we ever want to understand the human brain, which I have my doubts. I’d probably do it if it didn’t involve basically a vow of poverty.
Re: A single memory is stored across many connected brain regions
#9Their study looks not specifically at a storage site, but that along with the sites for processing a new memory for storage, and processes for recalling a memory from storage.
When you see something, that visual input is processed in a certain area that, IIRC, is the same area that is fired when recalling a visual memory.
When a memory is recalled, it is processed by the same regions that interpreted it initially upon first experiencing the stimulus. Compare that to a computer pulling a png from storage, loading into memory, calling necessary drivers to present onscreen, etc.
Re: A single memory is stored across many connected brain regions
#10I've never really loved contextual fear conditioning as the default for "memory". Another way of describing this result is that "even a mild trauma scars the entire brain." In all seriousness, though, I'd say that there's a broad dispute in the field between those that believe that memory involves dynamic neural activity involving a multiplexed circuit of neurons that encode many different memories and those (current…
Do we actually know how the memory is coded specifically? Is it a specific firing of a neuron (or a neuron ensemble), is it the specific answer you get from exciting the neuron(s)? Or any combination thereof?
IANA neuroscientist, so please correct me if I'm wrong or oversimplifying:
IIRC one of the main cellular mechanisms thought to underlie memory is LTP(Long Term Potentiation) in glutamatergic neurons. There are different kinds of glutamate receptors, but we're interested in the two subtypes of ion channel based(ionotropic) Glut receptors, AMPA and NMDA.
AMPA is sort of your main receptor for propagating signals: it's activated first.
NMDA is much more complicated in that it requires binding both glutamate and another neurotransmitter, glycine, for the ion channel to open. But this ion channel can also be blocked by Mg²+ ions, which for reasons that currently escape me, is removed when the neuron depolarizes. Once NMDA is open, it has the downstream effect of upregulating the AMPA receptor, making more sensitive to future transmission, hence serving as a kind of "memory" of previous signals. I think the open question is more about understanding how memory as we know it emerges out of networks of these neurons, and less about the basic cellular mechanisms. And this is probably only one mechanism of LTP, then you have its opposite, Long Term Depression, which is also involved.
Of course, in science the answer is always more complicated than what can be gleaned from the hand-wavey explanations of some programmer on HN :)