Roles of dynamic linkage of stable attractors across cortical networks in recalling long-term memory |
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Authors: | Osamu Hoshino MeiHong Zheng Kazuharu Kuroiwa |
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Institution: | (1) Department of Human Welfare Engineering, Oita University, 700 Dannoharu, Oita 870-1192, Japan, JP;(2) Department of Information Network Science, The University of Electro-communications, Chofu, Tokyo 182-8585, Japan, JP |
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Abstract: | We propose a neural network model for a category-association task. By simulating the model, neuronal relevance of cortical
interactions to recalling long-term memory was investigated. The model consists of the left and right hemispheres, each of
which has IT (inferotemporal cortex) and PC (prefrontal cortex) networks. Information about visual features and their categories
were encoded into point attractors of the IT and PC networks, respectively. In the task, the IT network of the right hemisphere
was stimulated with a cue feature. After a delay period, the IT network of the left hemisphere was simultaneously stimulated
with the choice feature and an irrelevant feature. The cue and choice features belong to the same category, while the irrelevant
feature belongs to another category. To complete the task, the IT network must select the point attractor corresponding to
the choice feature. We demonstrate that the top-down pathway (PC-to-IT) triggers the retrieval of long-term memory of the
choice feature from the IT, and the bottom-up pathway (IT-to-PC) contributes to the maintenance of the retrieved memory during
the delay period. The key mechanism for the retrieval and maintenance of that memory is the dynamic linkage of attractors
across separate cortical networks. We show that a single hemisphere is sufficient for the memory retrieval, but it is advantageous
to use the two hemispheres because the retrieved memory is thereby retained with greater reliability until the brain chooses
the choice feature.
Received: 4 April 2001 / Accepted in revised form: 17 September 2002 / Published online: 20 January 2003
Correspondence to: O. Hoshino (e-mail: hoshino@cc.oita-u.ac.jp, Tel.: +81-97-554-7301, Fax: +81-97-554-7507) |
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