Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: @/antic on 09/04/2012 08:59:21
-
Hello
I have a few questions on memories:
1.What is a memory? How does a memory look/appear in the brain? Is it a particular chemical sequence? And are different memories of different things/events stored as different chemical sequences?
2.Is my brain of this morning different from my brain of this evening because I now have the memories of today stored in it?
3.In storing the memories of a dream, a lie a literary account or a film, how does the brain make the distinction between a dream of a particular incident, a lie of the same incident; a literary or film version of the same incident and the memory of the actual incident as it occured in reality ?
4.Does the brain store information, say, about my mothers face, in my brain the same way that it stores the information of our mothers face in my sisters brain? Is the memory of the same person (face recognition in this case) the same (i.e. same chemical sequence?) in all individuals who are recalling a memory of the same face?
Cheers
Atlantic
-
1. One memory is one collection of "trained" or "reinforced" neuron connections, but one neuron can be part of multiple memories/collections. When studying for example, you are training certain connections which make you remember your course when making the exam.
2. Your brain is no two seconds in your entire life anatomically/physiologically the same.
3. Context. Your brain does not store "the incident" as such. It stores the memory of the moment you are watching/reading/hearing about the incident and places it in that context (movie, dream, book, ...). If someone tells you a lie about an incident, and does it convincingly, it will not be stored as a lie since you believe it. But if later, it is revealed that it was a lie, there will be a conflict in your brain and your brain will decide which truth to accept. Schizophrenic patients have trouble in this area.
4. The mechanism of storage will be the same. The locality in the brain will be roughly the same, ie: it will be in the same area of the brain, but not in exactly the same neurons. This is because no two brains are identical anyway, not even the ones from identical twins.
-
You may wish to read about Neural Networks, Imprinting, and the Grandmother Cell Theory.
While no true "Grandmother Cell" has been found, there is significant amounts of information consolidation, especially with visual processing where scenes are broken down from essentially pixels into edges, lines, contrast, and through successive layers into more complex structures.
The brain does an extraordinary job at filtering pertinent and not-so-pertinent information. Most models actually have a distributed storage mechanism, rather than in a specific location like a computer. So, if you cut out a small portion of the brain, memories may remain largely intact.
There are regions of the brain with specialized processing such as Wernicke's area and Broca's region, both very important for visual processing. The hippocampus and thalamus are involved in the transfer of short term memory to long term memory. Sleep and dreaming may also be important with memory formation.
-
Hi Nizzle,
1. Yes, it is neuronal connections, but I needed more than that because every memory is different and I needed to know what is the nature of the neuronal connections that makes a particular memory unique? Would the neurons be a unique chemical sequence for every memory?
2. True, the brain is different at any given moment. When one memorises something into long term memory, would the brain actually hard wire that memory (again, as a unique chemical sequence) into the brain?
3. Correct that the brain does not store and incident, but codes for the memory. If I told a lie and yet also remembered the truth about an incident, how would my brain differentiate between the two when I wanted to recall it? Ditto with reading it in a book, watching it in a movie, how does my brain know which memory of the incident is the lie, the literary version, the movie version and the reality? In what way are the neuronal connections different for each of those?
4. My apologies. My question wasn’t clear enough: would the memory of my mother be encoded as the same chemical sequence in the brains of both my sister and me if we are both recalling a memory of our mother? I personally don’t think it would be, which brings up the question of epistemology in philosophy, but....it still begs the question: how do we encode memories of same person in different brains?
Hi Clifford,
Thank you very much !
Really interesting leads there, which I will certainly look into.
Cheers!
Atlantic :)
-
The odd thing about memory is that unlike certain skills or functions (like those related speech, or movements) it is impossible to erase a single memory by destroying a group of cells or small section of the brain. Individual memories seem to be "shared" throughout large areas of the brain. In one anatomy lecture I heard by a surgeon, he compared memories to a hologram, which was an interesting analogy.
-
Hi Nizzle,
1. Yes, it is neuronal connections, but I needed more than that because every memory is different and I needed to know what is the nature of the neuronal connections that makes a particular memory unique? Would the neurons be a unique chemical sequence for every memory?
I believe the uniqueness of each memory has not much to do with chemical sequences, rather with which neurons are involved. It's unclear what you mean with "chemical sequence"? Do you perhaps mean "anatomical sequence", or are you talking about neurotransmitter sequence? Like, first a neuron gets dopamine signals, then acetylcholine, then serotonin, ...
2. True, the brain is different at any given moment. When one memorises something into long term memory, would the brain actually hard wire that memory (again, as a unique chemical sequence) into the brain?
When you sleep, short term memories get transcribed in long term memories. However, this is not an exact science and depends on a lot of factors. The hard wiring you refer to, could be seen as "a preparation of a neuronal connection, facilitating a future firing". I usually make this metaphor: If you're beating a tree with your hands all day long, as some shaolin monks do, your hands will get more callous and they will be better equipped for future tree-beating. That's what you do with your brain when storing memories. You're training specific neuron connections and reinforcing them so you can access them more easily in the future.
3. Correct that the brain does not store and incident, but codes for the memory. If I told a lie and yet also remembered the truth about an incident, how would my brain differentiate between the two when I wanted to recall it? Ditto with reading it in a book, watching it in a movie, how does my brain know which memory of the incident is the lie, the literary version, the movie version and the reality? In what way are the neuronal connections different for each of those?
Did you know that when you're consciously telling a lie, your brain is using much more oxygen and sugar compared to when you're telling the truth, or at least what your brain has accepted as being the truth. Your brain can easily repeat a truthful memory, but when you know the truth, and telling a lie about it, it starts from the truthful memory and needs to work on it to make it a lie before sending the signals to your voice box and lips and tongue. So, a lie is a variation of the memory of the truth. What you see in movies or read in books, your brain will categorize in "truth", "lie", or "fiction". Now to your question "How does the brain know which is which?" Your brain is a clean slate at the very beginning of it's development (i'm talking pre-birth now) and will be molded and modeled from the very start by all sensory input it gets (tactile, visual, hearing, pain, ....) This leads to what is called "your reality". Every memory in your life can be brought back to a combination of sensory inputs, processed by your cognitive functions (example: eyes see inky symbols on paper, brain makes words of them because it has memories stored of each inky symbol), then tested against "your reality", and subsequently incorporated into "your reality". So "your reality" is also changing every second of your life. Every new incoming blend of sensory inputs (a future memory) that is in conflict with "your reality" will be perceived as a lie, even if it's not a lie. Example: a person that has only read fairy tales could say to you "All books start with Once upon a time.." and be truthful about it, because it does not conflict with "his/her reality", but it does conflict with your reality, because you have read other books too.
4. My apologies. My question wasn’t clear enough: would the memory of my mother be encoded as the same chemical sequence in the brains of both my sister and me if we are both recalling a memory of our mother? I personally don’t think it would be, which brings up the question of epistemology in philosophy, but....it still begs the question: how do we encode memories of same person in different brains?
See also my response to question 3.
To recap how brains store memory.
1. Combination of all sensory inputs come in at the same time.
2. Processing by brain occurs. Instructions for processing are retrieved from previous memories.
3. Post-processed sensory inputs are tested against current state of conscious brain (your reality)
4. Post-processed and tested sensory inputs are incorporated in, and alter the current state of conscious brain (your new reality)
5. Back to 1. :)
IMPORTANT: Emotions also play a very important role in formation of reality, and your emotional state is very significant in all steps (1 through 4) in the above. Strong negative/positive emotions will lead to intense memories (the ones that will last a very long time), and the nature of the emotional state (happy, sad, stressed, tired, ...) will affect the context/content of the memory.
So, two persons sharing memories of the same person might remember that person in a different way. For example, your mother could have always been very nice to your sister, but very rude to you. You received different sensory inputs from the same person, which alter your reality in a different way.
Then, our brain also has a deeper layers, the unconscious layer, left-over primal instincts. Not much is known about this yet, and I'm not going to speculate :)