2000). This approach is effective at stopping searching, but invokes additional neural processes related to contrast perception not necessarily utilized during the searching condition. Finally, in the context of surgical treatment planning, it is also of interest to minimize fast-changing and high-contrast images in

the task (e.g., flashing lights), as this may reduce the risk of seizure (Zifkin and Trenite 2000). The purpose of this work was to develop and Inhibitors,research,lifescience,medical evaluate a CVS that was capable of generating consistent activation in the basic and higher level visual areas of the brain by using a high number of distractors as well as an optimized contrast condition. We further sought an implementation that minimized overall image contrast between conditions. Finally, we aimed to fully evaluate the activation and deactivation properties of the Inhibitors,research,lifescience,medical task throughout the entire brain. We developed a CVS based on an array of 60 blue squares and 60 red circles (120 total distractors) in which the task was to identify whether or not the array contained a blue Inhibitors,research,lifescience,medical circle. We analyzed images of 10 healthy volunteers scanned using fMRI with the CVS task used for stimulus. After individual and group processing,

the resulting data sets were analyzed using a nonbiased ROI approach to determine the regions of greatest activation and deactivation. The activation properties of the new task are presented in terms of activation extent and mean z-statistic across three levels of anatomy. Materials and Methods Participants Images of 10 healthy, right-handed Inhibitors,research,lifescience,medical volunteers were used in this study. The local

Institutional Review Board approved the use of the images in this study. Task The CVS task used in this study was based on similar tasks described in the neuropsychological and cognitive science literature (Kristjansson et al. 2002; Shen and Reingold 2003; Muggleton et Inhibitors,research,lifescience,medical al. 2008; Saevarsson et al. 2008). The task was implemented in a block design paradigm consisting of two repetitions PD184352 (CI-1040) of an 8-sec rest stimulus followed by two repetitions of an 8-sec task stimulus. Each paradigm thus had 16 sec of rest followed by 16 sec of task for a total paradigm length of 32 sec. The paradigm was repeated 12 times for a total experimental time of 6 min 24 sec. An overview of the stimuli is shown in Figure ​Figure1.1. The rest stimulus (Condition 1) began with a 1-sec presentation of a single red X centered on the screen. A random array of hollow blue squares and hollow red circles was then presented. Subjects were instructed to immediately click their right index finger upon presentation of the array, causing it to be blurred so that the CCI-779 shapes could no longer be determined. The task stimulus began with a 1-sec presentation of a blue circle centered on the screen.