In order to analyze the association of the periodontitis severity withchanges of the human dental pulp, one hundred caries-free and restoration-free periodontallyinvolved teeth with different periodontic destruction were studied histologically. It wasfound that there was correlation between the severity of periodontitis and changes in thehuman dental pulp. The incidence of pulpal pathosis rose as the periodontic destructionbecame severe. Pulpal inflammation was related to periodontitis, but not to the severityof periodontitis. Pulpal necrosis was mostly found in the teeth with advanced periodonti-tis.

Animal survival necessitates adaptive behaviors in volatile environmental contexts. Virtual reality (VR) technology is instrumental to study the neural mechanisms underlying behaviors modulated by environmental context by simulating the real world with maximized control of contextual elements. Yet current VR tools for rodents have limited flexibility and performance (e.g., frame rate) for context-dependent cognitive research. Here, we describe a high-performance VR platform with which to study contextual behaviors immersed in editable virtual contexts. This platform was assembled from modular hardware and custom-written software with flexibility and upgradability. Using this platform, we trained mice to perform context-dependent cognitive tasks with rules ranging from discrimination to delayed-sample-to-match while recording from thousands of hippocampal place cells. By precise manipulations of context elements, we found that the context recognition was intact with partial context elements, but impaired by exchanges of context elements. Collectively, our work establishes a configurable VR platform with which to investigate context-dependent cognition with large-scale neural recording.
Animals ; Mice ; Rodentia ; Virtual Reality ; Cognition ; Recognition, Psychology