Multiple representation and processing of information by neural networks in the primate prefrontal cortex

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This project was planed to analyze (1)how the neural circuitry in the dorsolateral prefrontal cortex(DLPFC) achieves multiple and flexible representation of a variety of information, (2)what changes could be observed in the information represented on the neural circuitry during information processing, (3)what kinds of rules regulates these changes of the information, and (4)what neural mechanisms accomplish these changes, based on a population of neural activities observed in the DLPFC which plays an important role of multi-modal information processing.We collected single-neuron activity from the DLPFC while monkeys performed several kinds of behavioral tasks. In the ODR task, monkeys were required to perform memory-guided saccades to the position where the visual cue had been presented. In the O-ODR task, monkeys were required to perform memory-guided saccades to either the right, left, upper, or lower direction based on the cue color presented on the fixation point. In the S-ODR task … More , visual cues were presented simultaneously at the right, left, upper, and lower positions, and the monkeys were required to make a saccade any one of these targets after the delay.We could not observe clear topographic distributions between neurons representing spatial information and neurons representing non-spatial (color) information in the DLPFC. We rather observed extensive overlaps of the distributions of these neurons, although the centroids of the distributions were different between these two groups of neurons. However, the cortical distribution of neurons representing visual information is different from the distribution of neurons representing saccade information, depending on the location where the visual cue was presented or the direction where the saccade was directed. These results suggest that a variety of information is represented by the difference of the spatial pattern of a population of neural activities. Therefore, information processes in the cerebral cortex could be considered as the change of the spatial pattern of a population of neural activities. However, it is not yet known what mechanisms cause such change in a population of neural activities. To understand these mechanisms, we need to understand interactions among neurons and population of neurons physiologically. Less