The prefrontal cortex as a model system to understand representation and processing of information

Working memory includes temporary active maintenance of information as well as processing of maintained information. Delay-period activity observed in the prefrontal cortex has been shown to be a neural correlate of the mechanism for short-term active maintenance of information. Using spatial working memory tasks, it was found that a great majority of delay-period activity represents retrospective information (e.g., the location of the visual cue) whereas a minority represents prospective information (e.g., the direction of the forthcoming movement). In addition, using population vector analysis using a population of prefrontal activities, the temporal progression of information processing can be seen as a temporal change of the direction as well as the length of the population vector during the delay period. The mechanism participating in the gradual change of information represented by a population of activities remains unresolved. However, functional interactions among neighboring neurons representing different information and dynamic modulation of these interactions depending on the context of the trial could be a mechanism of this process.