Where is Memory Stored in the Brain?

[Anonymous 69]

Everyone remembers the things that happen to them, which we call it memory. But where is the memory stored and how is it stored ? I mean in which part of the brain and in which state.

 

[Drakkith]

But where is the memory stored and how is it stored ? I mean in which part of the brain and in which state.

It is believed that memories are stored as synaptic connections in specific areas of the brain. That means that incoming information causes a number of neurons inside the brain to strengthen/weaken their connections, and this specific pattern of stronger or weaker connections forms the basic memory 'pattern'. In addition, different areas of the brain have different roles in memory formation, recall, and processing. Wiki says the following:

Brain areas involved in the neuroanatomy of memory such as the hippocampus, the amygdala, the striatum, or the mammillary bodies are thought to be involved in specific types of memory. For example, the hippocampus is believed to be involved in spatial learning and declarative learning, while the amygdala is thought to be involved in emotional memory.

 

[Anonymous 69]

It is believed that memories are stored as synaptic connections in specific areas of the brain. That means that incoming information causes a number of neurons inside the brain to strengthen/weaken their connections, and this specific pattern of stronger or weaker connections forms the basic memory 'pattern'. In addition, different areas of the brain have different roles in memory formation, recall, and processing. Wiki says the following:

Thank you but that doesn't clear my dout

 

[Laroxe]

Well I hope this doesn't make that worse. Drakkith's response does represent the current most widely accepted theory of how memories are stored, the brain is surprisingly active and constantly remodelling neural synapses.
You asked where is memory stored, well generally most people would say in the brain, but we do know that simple organisms without a brain are capable of memory its not impossible that some types of memory may be present in other tissues. Which leads us to the next problem when we talk about memory we are actually talking about lots of different things. Some memory can occur at the site of sensation, this happens in the eyes, but it only lasts 1 or 2 seconds, however it is thought that we do have areas that specialise in particular types of sensory information like visual memories. It seems that memory of an event doesn't mean that memory is all stored together, bits can be scattered everywhere, recall is more of a reconstruction. The areas we are most familiar with like the hippocampus are most likely to be responsible for how memories are stored and how they are associated together, the organisation seems very complicated it is also highly redundant, with lots of potential copies. Memories are also given an emotional valence which effects storage and recall, our current emotional state also influences recall and can be a powerful cue. Maybe being unclear is as good as it gets at the moment, but its still an impressive system, however it works. :)

 

[Drakkith]

You asked where is memory stored, well generally most people would say in the brain, but we do know that simple organisms without a brain are capable of memory its not impossible that some types of memory may be present in other tissues.

I strongly suspect this is either incorrect, or it's missing context. Can you provide a reference supporting it?

Some memory can occur at the site of sensation, this happens in the eyes

That doesn't seem right to me. As far as I know no memories are storied anywhere along the optic track.

It seems that memory of an event doesn't mean that memory is all stored together, bits can be scattered everywhere, recall is more of a reconstruction.

That is my understanding as well. Memories are stored in a 'compressed' form and have to be rebuilt using other parts of the brain and perhaps other memories as well. So if you recall a memory about playing fetch with your dog as a kid, your mind actually fills in many of the details using its general knowledge of things like dogs, fetch, tennis balls, etc. It's not a strict copy of the event that remains nearly unchanged over time.

Memories are also given an emotional valence which effects storage and recall, our current emotional state also influences recall and can be a powerful cue. Maybe being unclear is as good as it gets at the moment, but its still an impressive system, however it works. :)

Absolutely. I like to think of the brain as something like a 'hardened' computer system. By that I mean that the brain has to work in a downright hostile environment and evolution has taken steps to ensure that out brains still work even though cells are damaged and can die, synapses can be disrupted, food and fuel can temporarily be lost, etc. This has led to the brain being an extremely resilient organ, but with the cost that not everything works as well or as efficiently as one might naively expect.

 

[Drakkith]

Thank you but that doesn't clear my dout

Then please elaborate on what additional information you are seeking.

 

[Laroxe]

[QUOTE="Drakkith, I strongly suspect this is either incorrect, or it's missing context. Can you provide a reference supporting it?

This is an issue that depends a great deal on definition of memory and I seem to remember it was based on the idea of cells being able to adopt patterns of behaviour. The gut for instance continues to function and can vary its performance without most of its links to the brain. I'm not sure it would be possible to claim it was totally disconnected but cutting major nerves was a common enough surgical procedure. I think the question comes up because of animals studies and with the complexities of intra cellular signalling and the control of gene expression it does seem theoretically plausible.

https://phys.org/news/2013-08-flatworms-memories-brain.html

That doesn't seem right to me. As far as I know no memories are storied anywhere along the optic track.

Iconic memory is the sensory store for vision, First described by George Sperling (1963), there is also echoic memory.

The sensory stores are like brief delay systems associated with each sense. They preserve the pattern of stimulation before it enters attention. The sensory stores are sensory systems, but they are also memory systems because they preserve information after the external stimulus is gone.
The iconic image is complete. It contains all the sensory information available from the retina of the eye. However, it lasts only a fraction of a second and cannot be conjured up voluntarily at a later time. Probably the location of the iconic image is the circuitry of the retina itself.

Complex experimental techniques reveal that individual sensory traces or "pictures" can also be preserved in visual processing areas of the brain for up to five minutes. (Ishai and Sagi, 1995). This is not the same as iconic memory its a short term sensory store that is accessible.
It seems in some animals like amphibians a great deal of processing of sensory information happens at the site of sensation. Our olfactory nerve, which isn't really a nerve but a brain structure might reflect this.

Some experimental stuff;

https://www.frontiersin.org/articles/10.3389/fpsyg.2014.00971/full

That is my understanding as well. Memories are stored in a 'compressed' form and have to be rebuilt using other parts of the brain and perhaps other memories as well. So if you recall a memory about playing fetch with your dog as a kid, your mind actually fills in many of the details using its general knowledge of things like dogs, fetch, tennis balls, etc. It's not a strict copy of the event that remains nearly unchanged over time.

Yes I've heard people say that every recollection is in fact a creative activity and that, that will also influence future recollection, it edits the memory.

Absolutely. I like to think of the brain as something like a 'hardened' computer system. By that I mean that the brain has to work in a downright hostile environment and evolution has taken steps to ensure that out brains still work even though cells are damaged and can die, synapses can be disrupted, food and fuel can temporarily be lost, etc. This has led to the brain being an extremely resilient organ, but with the cost that not everything works as well or as efficiently as one might naively expect.[/QUOTE]
The whole model of how neurones work seems to be falling apart, the idea of a synapse activating and providing a stimulus that alters the action potential of the the other neuron is apparently way off. Individual dendrites can be allocated a different stimulus value and the information transmitted is not a simple all or nothing response, there can be quite a lot of variance in the signal. Its been suggested that we need to think of each neuron as a computer, sorry I havn't the source's immediately to hand but it gets more complex by the minute.

 

[Drakkith]

This is an issue that depends a great deal on definition of memory and I seem to remember it was based on the idea of cells being able to adopt patterns of behaviour. The gut for instance continues to function and can vary its performance without most of its links to the brain. I'm not sure it would be possible to claim it was totally disconnected but cutting major nerves was a common enough surgical procedure. I think the question comes up because of animals studies and with the complexities of intra cellular signalling and the control of gene expression it does seem theoretically plausible.

I would say that this is a very different type of 'memory' than what the OP is asking about. The cells in your body have a great many pre-programmed responses to different signals, but to say that their behavior is a type of memory requires that we broaden our definition a great deal. I would say that these two different types of memory are so different from one another that there is little point in grouping them into the same broad definition for this thread.

Iconic memory is the sensory store for vision, First described by George Sperling (1963), there is also echoic memory.

The sensory stores are like brief delay systems associated with each sense. They preserve the pattern of stimulation before it enters attention. The sensory stores are sensory systems, but they are also memory systems because they preserve information after the external stimulus is gone.
The iconic image is complete. It contains all the sensory information available from the retina of the eye. However, it lasts only a fraction of a second and cannot be conjured up voluntarily at a later time. Probably the location of the iconic image is the circuitry of the retina itself.

Ok, I see what you're saying. But again I think this is a very different type of 'memory' than the OP is asking about. I would say that this has more to do with the local processing functions of the brain than it does with higher-level memory storage, generation, and retrieval.

The whole model of how neurones work seems to be falling apart, the idea of a synapse activating and providing a stimulus that alters the action potential of the the other neuron is apparently way off. Individual dendrites can be allocated a different stimulus value and the information transmitted is not a simple all or nothing response, there can be quite a lot of variance in the signal. Its been suggested that we need to think of each neuron as a computer, sorry I havn't the source's immediately to hand but it gets more complex by the minute.

No worries, that's essentially my understanding as well. In fact I'd be surprised if individual neurons had no way of altering how much they respond to different stimuli. Cells have consistently shown that they are far more complex and capable than we first believed.

Also, if you want to quote individual sections of someone's post, highlight the section of text and use the 'quote' option instead of the 'reply' option. This puts that text into a que and you can then insert the contents of that que into the reply box using the 'Insert Quotes' button that appears at the bottom left of the reply box.

 

[256bits]

The whole model of how neurones work seems to be falling apart

Are you referring to recent discoveries of new brain cells. If not, at least these discoveries do add to the complexity of the brain.

For mice AND humans (2014 )
https://www.livescience.com/47958-new-brain-cell-discovered.html

For NOT mice but only humans(2018)
http://www.sciencemag.org/news/2018/08/mysterious-new-brain-cell-found-people

 

[atyy]

Everyone remembers the things that happen to them, which we call it memory. But where is the memory stored and how is it stored ? I mean in which part of the brain and in which state.

Memories are stored by synaptic changes in many different parts of the brain, depending on what type of memory is involved.

Here is some direct evidence that fear memory is at least partially stored by changes in the synaptic strength of neurons in the amygdala.
https://www.ncbi.nlm.nih.gov/pubmed/15746389
Postsynaptic receptor trafficking underlying a form of associative learning.
Rumpel S, LeDoux J, Zador A, Malinow R.
Science. 2005 Apr 1;308(5718):83-8.

 

[BillTre]

The whole model of how neurones work seems to be falling apart, the idea of a synapse activating and providing a stimulus that alters the action potential of the the other neuron is apparently way off. Individual dendrites can be allocated a different stimulus value and the information transmitted is not a simple all or nothing response, there can be quite a lot of variance in the signal. Its been suggested that we need to think of each neuron as a computer, sorry I haven't the source's immediately to hand but it gets more complex by the minute.

I take a different view of this stuff.
Rather than seeing the concept of the neuron (as I see it anyway) as falling apart, I see it as being elaborated upon.
Action potentials are still affected (usually indirectly) by synaptic inputs, but there are other ways neural activity can be affected and increasingly more subtlety is being revealed.

 

[Feeble Wonk]

While this is a fascinating discussion, it seems that there’s a definite need to define our terms. Some types of “memory” referred to here would appear to be more generally described as physiological function or neurological reflex behavior. Similar descriptions could be made regarding subconscious instinctual behavior demonstrated by uncountable species of life. If “memory” in this context is more specifically defined as the conscious recollection of previous events, I’d think that it’s safe to localize that phenomenon primarily in the neural tissue of the brain. Of course, that leads to the slippery slope of defining the conscious experience, so it’s best to tread carefully here.

 

[Laroxe]

I agree that the definitions we use are central but this is an issue that continues to cause problems across the whole of memory research. You suggest that some types of memory appear to be a physiological function or reflex. You could certainly argue that all memory reflects physiological functioning. Some people suggest that memory is defined by a specific environmental response altering future behaviour even simple conditioning reflects that something about a stimulus has been stored in some way and continues to function. Reflexes tend to be fixed responses so wouldn't count unless you could modify the links between a stimulus and the behaviour. Words like subconscious and conscious experience would render any idea of memory in animals useless, we can only access conscious experience in humans. We must be able to infer some sort of memory based on behavioural responses to specific stimulus. Unfortunately this takes us right back to the problem of explaining the ability simple life forms, with no CNS ability to modify their behaviour towards novel stimuli upon recognition of threat (usually noxious chemicals) leading to a much more rapid response.
Maybe it would be easier to be clearer in describing the sort of memory the question is about, well a bit easier anyway. :)