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There are several answers and articles about how the brain stores data, but none specifically cover whether a human's brain stores duplicate data.

I was reading in this article that a human brain can have a capacity of 1 terabyte to 2.5 petabytes. But for example, if you read a book a dozen of times, will it be stored as data several times?

Let me put it this way. When we read a book a couple of times, we remember it better. Is that because it's stored in several synapses and then retrieved better while trying to remember, or is it because reading it over and over makes the missing parts be stored?

We do recognize a familiar phrase when reading a book, which means the brain can differentiate the unknown from known. What matters is that does it decide to store it again or not? Just like a computer who refuses to save a file if the file already exists.

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    $\begingroup$ It would appear that we do 'instantaneously' store duplicate data, if a recent provocative paper in Science is correct, showing that memories are formed simultaneously in the hippocampus and the cortex. This paper challenges the view that short term memory is due to initially storage in hippocampus, and that permament memory is due to slow consolidation over time in the neocortex. See Rules of memory 'beautifully' rewritten for a very interesting read. $\endgroup$ – user1136 Apr 14 '17 at 8:03
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    $\begingroup$ You might think about what gets stored when reading a book. First there's the actual text, which (if you read it a number of times and make an effort) you might memorize and be able to recite, and which can be stored in a Mbyte or so of ASCII. Then there's the story the book tells, which you could remember even if you can't remember the actual words. Then there are the various experiences of reading a book that you might have read multiple times over the years. How much space does it take to store the memory of those experiences? $\endgroup$ – jamesqf Apr 15 '17 at 1:05
  • $\begingroup$ @jamesqf Yes, i mentioned this in my comment to the answer indeed. Some phrase in other language that you don't even know, but you remember how to repeat it. $\endgroup$ – Jack Johansson Apr 16 '17 at 4:58
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The way neuroscientists currently think about storage in the brain, it doesn't make any sense to think about "duplicate" data but rather about the "robustness" of a given memory to interference or confusion, which increases with consolidation and reconsolidation of memories or can degrade over time.

Repeated exposure can contribute to the robustness of a memory, but so can other factors such as the emotional content of a memory (which, depending on the emotional state, can increase or decrease memory robustness, and this can also vary with the "jist" versus "detail" of a memory).

Note that there are also very different types of memory, so that repetition is very important for motor plans and "muscle memory" whereas episodic memory can get lost in the repetition of daily recurrent events, such as parking your car or eating lunch: you might remember where you parked or ate today, but if you have a routine this can blur into all one memory, where you have a notion of eating at a particular restaurant many times, but you would struggle to remember specifically eating there on December 14th, 2011, unless there was some other special event on that day.

In your example of reading a book, there would likely be two types of memory: 1) memory for the episodic event of reading the book, which would be a separate memory because it is a separate event, though it could be confused with other similar episodic events. 2) Semantic memory for the content of the book: this would be a single memory, reinforced with subsequent readings of the book, and supplemented with all your other semantic experience with the content of a book: discussing the characters of a fiction book with your friends, learning about molecular genetics from a textbook and from a lecture course, etc.

Note also that talking about the "data capacity" of a human brain compared to a computer is a bit silly, because data isn't stored in the nervous system in bits, and a "fair" accounting of human memory needs to consider the vastly multidimensional interactions that are easily coded in a nervous system but not at all easily in a binary system. Note that other papers have come up with estimates that diverge greatly from the numbers you cite, for example Wang et al 2003 which gives a value of 108432 bits based on the number of synaptic connections. That number is truly inconceivable to our conscious experience even if it is within the capability of our brain. Clearly there are other limiting factors not involved in a simple binary system, for example confusion with similar memories, and there are types of memory that computers excel at (such as the pixel values of an image) whereas human memory deals in abstractions and hierarchical representations.

References


LaBar, K. S., & Cabeza, R. (2006). Cognitive neuroscience of emotional memory. Nature Reviews Neuroscience, 7(1), 54-64.

Walker, M. P., Brakefield, T., Hobson, J. A., & Stickgold, R. (2003). Dissociable stages of human memory consolidation and reconsolidation. Nature, 425(6958), 616-620.

Wang, Y., Liu, D., & Wang, Y. (2003). Discovering the capacity of human memory. Brain and Mind, 4(2), 189-198.

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  • $\begingroup$ Thank you. Here i have to mention: 1- What do you mean by Robustness? For example, a signal's robustness can be divided into signal strength, signal quality, etc. 2- By reading book, i meant simply remembering words and their orders, such as you remember a phrase from a language you don't even understand. $\endgroup$ – Jack Johansson Apr 13 '17 at 19:53
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    $\begingroup$ 1) I meant resistance to factors that interfere with signal. In memory, two of these are interference and confusion. Interference I would say is roughly equivalent to signal-to-noise, the inability to recall a particular memory. Confusion has a particular meaning in theoretical descriptions of memory as well, slightly different from the colloquial usage, but it basically means the ability to distinguish two different patterns. Also called "pattern separation" from the other direction. 2) This meaning would be the "semantic" type of memory that I mentioned. $\endgroup$ – Bryan Krause Apr 13 '17 at 20:05
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    $\begingroup$ For 1) in robustness I would also include, to some extent, the level of detail of the memory, though it could be possible for a memory to be very clear but not detailed, all of those qualities are not necessarily dependent on each other. $\endgroup$ – Bryan Krause Apr 13 '17 at 20:07

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