Spatial affect learning restricted in major depression relative to anxiety disorders and healthy controls.

Detecting and learning the location of unpleasant or pleasant scenarios, or spatial affect learning, is an essential skill that safeguards well-being (Crawford & Cacioppo, 2002). Potentially altered by psychiatric illness, this skill has yet to be measured in adults with and without major depressive disorder (MDD) and anxiety disorders (AD). This study enrolled 199 adults diagnosed with MDD and AD (n=53), MDD (n=47), AD (n=54), and no disorders (n=45). Measures included clinical interviews, self-reports, and a validated spatial affect task using affective pictures (IAPS; Lang, Bradley, & Cuthbert, 2005). Participants with MDD showed impaired spatial affect learning of negative stimuli and irrelevant learning of pleasant pictures compared with non-depressed adults. Adults with MDD may use a "GOOD is UP" heuristic reflected by their impaired learning of the opposite correlation (i.e., "BAD is UP") and performance in the pleasant version of the task.

Detection of deception using fMRI: better than chance, but well below perfection.

Functional brain imaging has been considered a new and better technique for the detection of deception. The reasoning is that there is a neural locus or circuit for lying that is sensitive, specific, generalizable across individuals and measurement contexts, and robust to countermeasures. To determine the extent to which the group results predicted lying at the level of the individual, we reanalyzed data on 14 participants from a study that had previously identified regions involved in lying (thus satisfying the criterion for sensitivity). We assessed the efficacy of functionally determined brain regions based on the lie-truth contrast for N-1 participants to detect deception in the Nth individual. Results showed that no region could be used to correctly detect deception across all individuals. The best results were obtained for medial prefrontal cortex (mPFC), correctly identifying 71% of participants as lying with no false alarms. Lowering the threshold for a response increased hits and false alarms. The results suggest that although brain imaging is a more direct index of cognition than the traditional polygraph, it is subject to many of the same caveats and thus neuroimaging does not appear to reveal processes that are necessarily unique to deception.

Opacity transfer function optimization for volume-rendered computed tomography images of the prostate.

RATIONALE AND OBJECTIVES: The selection of an opacity transfer function is essential for volume visualization. Computed tomography (CT) scans of the pelvis were used to determine an optimal opacity transfer function for use in radiotherapy. MATERIALS AND METHODS: On sample datasets (a mathematical phantom and a patient pelvis CT scan), standard viewing orientations were selected to render the prostate. Opacity functions were selected via (1) trapezoidal manual selection, (2) trapezoidal semiautomatic selection, and (3) histogram volume-based selection. Using an established metric, the errors using each of these methods were computed. RESULTS: Trapezoidal manual opacity function optimization resulted in visually acceptable images, but the errors were considerable (6.3-9.1 voxel units). These errors could be reduced with the use of trapezoidal semiautomatic selection (4.9-6.2 voxel units) or with histogram volume-based selection (4.8-7.9 voxel units). As each visualization algorithm focused on enhancing the boundary of the prostate using a different approach, the scene information was considerably different using the three techniques. CONCLUSION: Improved volume visualization of soft tissue interfaces was achieved using automated optimal opacity function determination, compared with manual selection.