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/sci/ - Science & Math

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2649624 No.2649624 [Reply] [Original]

On a physical level, how is memory stored in the brain? Is it chemical? Is it electrical?

Picture totally unrelated.

>> No.2649631

If only we knew for sure. The neurons could be "communicating" based on the intensity and frequency of firing. So, it's really both electric and chemical since neuronal firing is dependent on both.

>> No.2649641

biological, its the way the cells in your brain are connected

>> No.2649643

Also isn't the physical arrangement and synapse size/type important? At least for long term memories.

>> No.2649650

Up until recently, neurons were supposedly responsible for all of brain activity (electrical).

But then they discovered some other cells (can't recall the name) had some significant role, and operated chemically.

A bit of both, OP.

>> No.2649673

Last I heard it was more macroscale than individual neurons. More about the patterns that fire. So you can have one circuit that is very large and shares neurons with other circuits, meaning the concept of fruit, and apples. Someone said if you can find a neuron that only fires for one circuit, that means the neuron is devoted to that idea. I dont buy that, though.

Also some stuff about connection weights.

A question, when an impulse travels down an axon, is there any way that it gets directed to one connection over another? Or does it simply fire all of them? And how do you differentiate between different neurotransmitters, if all they do is induce the cell to fire? Just different contributions to the excitation? No quality difference?

>> No.2649680

Also what the hell are brain waves

>> No.2649688

>>2649673
Not sure if this is what you're asking but neurotransmitters are similar to the idea of enzymes. Certain keys only fit into certain locks.

>> No.2649689

Postsynaptic density of AMPA receptors determines synaptic weight in glutamatergic synapses in the cortex. These weights contribute to a weighted summation of all the inputs a given neuron has to determine if that neuron should fire, and with what frequency it will fire. This is incredibly similar to common paradigms of neural computing, which use synaptic weights to associatively map output patterns to input patterns.

The postsynaptic density of AMPA receptors increases by a clever mechanism involving camodulin, CaMKII, NMDA receptors and Mg+ ions whenever coincident firing of a presynaptic and postsynaptic neuron is detected. This process is equivalent to learning that any artificial neural network does.

tl;dr: its a chemical change that changes the strength of electrical synaptic potentials.

>> No.2649718

>>2649673
>A question, when an impulse travels down an axon, is there any way that it gets directed to one connection over another?

No. When it fires down an axon, it will fire in all directions that axon goes and it will activate all synapses that neuron makes on other neurons. What determines which postsynaptic neurons will fire is the synaptic weight, which is determined by postsynaptic receptor density.

>> No.2649720

>>2649680
Brain waves are event related potentials (changes in voltage) elicited during electroencephalographic scans. Its a term specific to the neuroimaging technique.

>> No.2649744

>>2649718
>>2649689
>>2649720
I thought you said you were going to bed. But since youre still here:

Whats the ratio of neurotransmitters released, to receptors? Are the neurotransmitters propelled towards the receptors in any way or is it simply dispersion (aside from molecular key/lock whatever attraction). Finally, how much of the time it takes to get from neuron A to neuron B is "wasted" in the neurotransmitters traversing the synapse?

>> No.2649750

memory forms in the hippocampus,

the best known mechanism for memory formation is long term potentiation which causes forming of new synapses by chemical signals (AMPA and NMDA) along with temporal and spatial summation of action potentials.

there are very well established methods to bring about long term potentiation.

>> No.2649772

>>2649750
>memory forms in the hippocampus
There is still not enough evidence to say that memory forms there. Yes, the hippocampus plays a very large role. But memories activate association areas throughout the brain. It is still unclear if the hippocampus is important for memory formation, consolidation, or something else.

>> No.2649806

>>2649744
I'm a different guy. First time logging on /sci/ today.

The exact ratio of transmitters to receptors I do not know (I'd imagine its dependent on the transmitter), but I do know(/believe) that the amount of transmitters a presynaptic cell releases is not plastic. Only the receptor density changes. ALSO, its worth noting that ligand:receptors activated is not necessarily 1:1. Nicotinic Acytylcholine receptors require the binding of two Acytylcholine molecules for their cation channel to open.

The transmitters move across the synaptic cleft by diffusion. They are not actively transported.

I do not know how much time it takes, but I'd imagine that it's very very small.

>> No.2649829

>>2649806
> the amount of transmitters a presynaptic cell releases is not plastic. Only the receptor density changes
Well thats goddamned interesting. I guess it makes sense though, easier to have control over a mechanism with one variable than one with two

Thanks for answering my questions

>> No.2649844

>>2649772
>>2649772


uhh i am a neuroscience major and yes there is may i point you to henry mollier who had his hippocampus removed and since then can not form new memories.

it is now clearly established that short term memory forms in the hippocampus and that the hippocampus then forms a sort of scaffold to help port the memories to long term memory which are stored outside the hippocampus.

I could write a 10,000 word essay on different sorts of memory formations and different mechanisms but the one of long term potentiation is the best established one.

so please show me your citation which is from after the 1980's where it says the hippocampus's role in memory formation is not clearly known.

sorry if I seem really aggressive im just very passionate about this lol

>> No.2649861

>>2649829
It is worth noting, however, that a mechanism for plasticity in the release of transmitters is POSSIBLE. The exocytosis of vesicles in the presynaptic cell is modulated by calcium ions, so changing the permeability of the terminal bouton to calcium (I.E., adding more calcium channels) would facilitate the intake of more calcium.

I don't know if an increase in presynaptic receptor density would actually make a difference here, though, as I don't know the calcium concentration extracellularly offhand.

>> No.2649865
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2649865

>> No.2649879

>>2649844
Its worth noting that H.M. had many more regions than his hippocampus removed.

Behavioral neuroscience has implicated the hippocampus in spatial memory formation, but that's the only real clear link we've drawn.

I mean, Damasio & Damasio showed us that to learn which deck is best in the iowa gambling task actually takes the amygdala and vmPFC. Learning is more complicated than a single region.

>> No.2649886

>medula oblongata

>> No.2649889

trolling a tiny bit,
but we will know by 2025

>>2649400

>> No.2649903

Memory experiment time, /sci/

Theres a famous black and white photograph of a blindfolded man being executed out in the street during the vietnam war. Really famous. Can you remember it? Do me a favor and remember it for a moment...

>> No.2649904

Wait, so new synapses are not formed? and even short term memories are based on the number of receptors? So the number of receptors changes?

>> No.2649914

>>2649904
Neurons decouple from eachother all the time, and reform as new connections. Somewhere in the double digits % of your brain is churned every six weeks or so. I wish I could find the article

>> No.2649915

>>2649903
He wasn't blindfolded. Yes, that will cue some of us to remember him being blindfolded. Yes, our memories are utter shit. Thanks, Dr. Loftus.

>> No.2649919
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2649919

>>2649903
this? he's not blindfolded though.

>> No.2649924

>>2649919
Yeah I was going to get to that. Got caught up in a different thread. The point was to try and get people to remember him being blindfolded, then get all pissed off when they see that they remembered wrong, showing "memory" to be pretty subjective, more like imagination

>> No.2649928

>>2649919
>>2649915
Ok, fine, how would YOU do it then

>> No.2649930

>>2649914
but why? I thought it was memory formation, and forgetting.

>> No.2649935

>>2649930
That sounds right, prune the unused branches so they don't interfere with more established/popular patterns, for clarity sake. Im pulling that out of my ass though

>> No.2649937

I'm curious if there was a way to decipher the information. I guess crack the code of memory.

I suppose this would be necessary to do what some people propose, which is copying our consciousness into data.

Is it yet possible to descipher it or are there any attempts into figuring it out?

>> No.2649941

>>2649919 here

>>2649928
do what?
>>2649924
I thought it was just a question, not a psycologist trying to fuck with my head. Seriously its this sort of thing that puts me off psychology, makes me paranoid.
Back on topic please, I want to know more neouroscience, I may do it at uni.

>> No.2649944

>>2649650
You're thinking of Astrocytes. An article on the subject recently appeared in Nature.

>> No.2649951

>>2649937
It kinda parallels with the genome, in that we will have soon worked out the connectome (how the neurones are connected) but we will probably have fuck all idea what it means.

>> No.2649953

>>2649829
>>2649806
Referring to:
>the amount of transmitters a presynaptic cell releases is not plastic. Only the receptor density changes

Just to throw something else into the mill, while not directly pertaining to LTP and memory formation. It's thought that amphetamines exert at least some of their action by influencing presynaptic release in dopamanergic neurones. (Rang and Dales would be my source for that). If it happens pharmacologically it likely happens physiologically.

From there it isn't too much of a leap to assume a similar thing couldn't happen in the gluatmatergic system as well. A potential mechanism for the plasticity would - at a guess - be alterations to the expression of the proteins involved in transport of glutamate out of the pre-synaptic knob.

I don't know, just puttin' ideas out there. Incidentally, how is glutamate released? Transporters? Vesicles?

>> No.2649956

Neuroscience seems complicated. Is there a science that just looks at the brain and behavior?

>> No.2649961

>>2649861
Ah shit, this dude got there before me (>>2649953)

>> No.2649962
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2649962

>>2649956
>is there a science that just looks at the brain and behavior
A science?
No.

>> No.2649963

>>2649956
If you're looking for a science that isn't complex, I have bad news. The specific study of the brain and behavior has many names, but Biospsychology is the most popular.

>> No.2649968

>>2649953
Would there be a benefit to enhancing release, rather than enhancing reception?

>> No.2649969

>>2649963
Thanks.

>> No.2649973

>>2649968
I would say no. The amount of receptors on the postsynaptic neuron is, after all, rather small compared to the amount of transmitters released.

>> No.2649979

>>2649968
My experience with evolution is similar to Murphy's law - if it can happen, it probably has.

>>2649973
Though this is a nice point.

>> No.2649981

It's stored in the strength of neural connections. When you remember something, the same pathways of neural connections gets travelled again. Memories often use the same neurons as others and overlap. When some of the same neurons are traversed but for a different memory, the connections will be reinforced for that memory but slightly weakened for memories that use those neurons. This is why you can store as many pieces of information as you want, but the more you have the blurrier they become.

>> No.2649987

Sage because thread is about science.

>> No.2649992

I bet the physics of this stuff is fascinating. Biophysics must be amazing at the neuronal level.

>> No.2650000

>>2649981
There is a parallel thread about nootropics, with people arguing about memory vs processing, Im going to crosspost your post if you dont mind

>> No.2650004

>>2650000
sure

>> No.2650059

Depends what kind of memory. If it's spacial relationship you'll find an increase in the actual number of neurons in the hippo to hold the additional information. If it's about linguistic relations or more abstract concepts you may find that it's more of a change to the already formed connections previously made in other sections of the brain to represent this change.

>> No.2650076

>>2650059
Is there something special about spatial relationships that they have to be clustered together? Or is just a relic of an inherited forebrain that we never were able to move past

>> No.2650256

>>2649941
Psychology and neuroscience are closely tied. Don't ever let anyone tell you otherwise. Unless you're in cellular neurobiology or physiology, you will be reading cognition literature.