For purposeful behaviors, accurate coding of time is always needed. However, little is known about where in the brain temporal cognition is achieved. To address this issue, we designed a time-reproducing task. In this task, the monkeys had to watch an LED illuminated for 1-7 seconds (cue period). After a delay period, the monkeys had to wait for the same time duration as indicated by the cue (go period) before pressing a button. Following sufficient training, the error rates for the shorter cues (1 or 2sec) were about half of those for the longer cues (≥ 4sec). Neuronal activity was recorded from the medial prefrontal cortex (i.e. area 9) during task performance. Many neurons were activated differentially according to the different time duration of the cue. Such time-selective activities were observed for all of the task periods. The present results suggest that the medial prefrontal cortex may be involved in temporal cognition.
In order to understand neuronal mechanisms systematically, it is important to integrate research results in various fields, such as morphology, physiology and immunology. We are developing a database system for sharing experimental and analytical knowledges. A new WWW technology, CMS (Content Management System), was implemented in our system. A PHP based CMS, XOOPS, provides several functions for web based database managements, for example, user accounting, page designing and data backup. The database was developed as an original module of XOOPS, for dealing confocal images, electrophysiological responses and other data files. Research resources in various fields are combined on the database for realizing conjunction of experiments and analysis, which will lead us to comprehensive understanding of the brain systems.