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Learning & Memory
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Holographic Memory |
| Molecular Biology Web Book | |
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The long term potentiation in the hippocampus is a temporary memory, lasting for a few hours to a couple of days. It is equivalent to the working memory (RAM) of a personal computer. After the computer is shut off, the working memory is gone, unless the contents have been saved in a hard disk. Some of the memory acquired in the hippocampus will be transferred to the cortex for permanent storage. This involves synthesis of new proteins and possibly formation of new synapses. The detailed mechanism is not clear. In the 1920s, Karl Lashley was trying to locate the exact area for memory storage. He trained rats to perform specific tasks, then impaired specific areas of the cortex. He found that the memories were reduced, but not removed by the lesions at any part of the cortex. This suggested to him that the memory was not stored at any specific area, but rather distributed over the entire cortex. In 1960s, Karl Pribram, who worked with Karl Lashley in the 1940s, proposed that the memory was stored as a hologram. The hologram was invented in 1947 by Dennis Gabor to record images in a medium (e.g., a crystal). It has a very unique feature, namely, any small part of the medium contains all information about the image. Therefore, even if the medium is broken into pieces, the entire image can still be obtained from any piece, except the resolution is reduced. The holographic storage of memory has at least the following advantages:
Because of these advantages, the brain memory may indeed be stored as a hologram. For physical memory disks such as DVD, the present technique has reached the upper limit of data density. Computer engineers are trying to use hologram for the next generation of data storage, because it may store significantly higher amount of information. In our brain, the holographic memory may also be able to store more information than other alternatives.
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