This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 9/17/2008 Our ability to rapidly process information and generate responses depends greatly on cognitive control, whose neural mechanisms have been extensively studied with recent advances in human brain mapping. Current theories of cognitive control have focused on the role of the anterior cingulate cortex (ACC) in conflict detection/resolution and response selection. However, these theories cannot account for the striking finding that patients with ACC lesions do not show deficits in conflict detection/resolution but rather overall slowness of response. Meanwhile, from behavioral and functional neuroimaging studies we have observed that (i) there is a robust correlation between overall reaction time (RT), the conflict effect, and ACC activation, and that (ii) the ACC is commonly activated in all cognitive task states compared to baseline state. The emerging evidence suggest that the ACC is a major determinant of information processing rate and response speed, as indexed by overall RT. Building on our and others' previous theoretical perspectives and these observations, we propose an information theory model of the ACC in which the ACC serves as a fast relay and integrative interface with dynamic interconnections between cortical and subcortical structures and plays a pivotal role in central cognitive control of rapid information processing and response, beyond traditional theories of conflict detection/resolution. In this project, we will assess functional activation and integration of the ACC and model its neural dynamics during rapid information processing and response in order to establish network-function relationships. Specifically, we hypothesize that: (1) the activity of the ACC and the dynamic functional/effective connectivity among the ACC and associated pathways are critically involved in these processes and determine the relative efficiency of these processes; and (2) the functional activity and dynamic connectivity of the ACC predict a significant proportion of individual differences in behavioral performance related to these processes.