Individual differences in cognition, affect, and performance: behavioral, neuroimaging, and molecular genetic approaches

We describe the use of behavioral, neuroimaging, and genetic methods to examine individual differences in cognition and affect, guided by three criteria: (1) relevance to human performance in work and everyday settings; (2) interactions between working memory, decision-making, and affective processing; and (3) examination of individual differences. The results of behavioral, functional MRI (fMRI), event-related potential (ERP), and molecular genetic studies show that analyses at the group level often mask important findings associated with sub-groups of individuals. Dopaminergic/noradrenergic genes influencing prefrontal cortex activity contribute to inter-individual variation in working memory and decision behavior, including performance in complex simulations of military decision-making. The interactive influences of individual differences in anxiety, sensation seeking, and boredom susceptibility on evaluative decision-making can be systematically described using ERP and fMRI methods. We conclude that a multi-modal neuroergonomic approach to examining brain function (using both neuroimaging and molecular genetics) can be usefully applied to understanding individual differences in cognition and affect and has implications for human performance at work.     

Glomerulitis during acute cellular rejection may be a surrogate marker of vasculitis in renal allografts--better index for diagnosis of vasculitis

Background

The Banff criteria (from 2005 to 2009) use “T cell-mediated rejection” to indicate acute cellular rejection. Vasculitis in smaller arteries is an important diagnostic criterion for moderate and severe T cell-mediated rejection. The renal allograft endothelium is a significant target of inflammatory response-mediated tissue damage. Medium-size arteries (arcuate arteries) are mostly absent in routine allograft biopsies, so identification of vasculitis relies on its identification in small arteries (arterioles to interlobar arteries). Although inflammation in terminal vessels such as the glomerular capillaries has been previously recognized, their role in grading the rejection process is not well characterized. We therefore evaluated the expression of CD3-positive T lymphocytes and CD68-positive macrophages in glomeruli, small arteries, and arcuate arteries of nephrectomy specimens obtained from transplant and renal tumor patients.

Methods

The study group included 21 renal explant subjects with nonreversible moderate to severe T cell-mediated rejection (IIa to III) and/or severe chronic changes. The control group comprised 17 individuals with nephrectomy for renal tumors. In each case, a large renal section from cortex to medulla was stained for CD3 and CD68 by immunohistochemical method. CD3-positive T lymphocytes and CD68-positive macrophages per balanced high-power field were counted in glomeruli, interlobar arteries, and arcuate arteries.

Results

In control kidney sections, neither CD3-positive T lymphocytes nor CD68-positive macrophages were noted in glomeruli, interlobar arteries, or arcuate arteries. In the study group, 15/21 showed diffuse C4d positivity. Also in the study group, positive CD3 and CD68 counts in glomeruli were significantly correlated to both interlobar and arcuate artery counts by linear regression analysis.

Conclusion

We conclude that in renal allograft biopsies, T lymphocytes and macrophages in the glomeruli not only represent a separate entity, “transplant glomerulitis,” but also may be a surrogate marker of vasculitis present in larger vascular beds. Comparable amounts of T cells and macrophages imply that “acute cellular rejection” may be a better terminology to reflect the true inflammatory status.     

Early interaction between perceptual load and involuntary attention: An event-related potential study

Whether selective attention affects C1, the first (earliest) visual cortical component of the event-related potential (ERP), remains controversial. We used a cued, involuntary attention task requiring discrimination of targets under low and high levels of perceptual load to examine early attentional modulation in visual cortex. Potential confounds due to physical stimulus differences between load conditions and cue–target sensory interaction were minimized. An interaction between perceptual load and involuntary attention was observed for the P1m component (peak latency between 100 and 140 ms). Furthermore, the parieto-central C1 component (peak latency 80 ms) was modulated by attention, but only under the high-load condition. Thus, whereas attention typically modulates the later P1 component, attentional modulation of C1 is possible under optimal conditions. Specifically, a high perceptual load is necessary for eliciting this earliest attentional effect on cortical processing.     

Assessments of Process Parameters on Cutting Force and Surface Roughness during Drilling of AA7075/TiB2 In Situ Composite

Reinforced aluminum composites are the basic class of materials for aviation and transport industries. The machinability of these composites is still an issue due to the presence of hard fillers. The current research is aimed to investigate the drilling topographies of AA7075/TiB₂ composites. The samples were prepared with 0, 3, 6, 9 and 12 wt.% of fillers and experiments were conducted by varying the cutting speed, feed, depth of cut and tool nose radius. The machining forces and surface topographies, the structure of the cutting tool and chip patterns were examined. The maximum cutting force was recorded upon increase in cutting speed because of thermal softening, loss of strength discontinuity and reduction of the built-up-edge. The increased plastic deformation with higher cutting speed resulted in the excess metal chip. In addition, the increase in cutting speed improved the surface roughness due to decrease in material movement. The cutting force was decreased upon high loading of TiB₂ due to the deterioration of chips caused by fillers. Further introduction of TiB₂ particles above 12 wt.% weakened the composite; however, due to the impact of the microcutting action of the fillers, the surface roughness was improved.     

Synthesis and antibacterial evaluation of 3,3′-diindolylmethane derivatives

Various 3,3′-diindolylmethane (DIM) derivatives were synthesized and the antibacterial activity of these compounds were tested against ten bacterial strains and their minimum inhibitory concentration (MIC) values were determined. The MIC values of derivatives 3a–d and 5a–e were ranging from 125 to 500 μg/mL. Among these derivatives, 2-(di(1H-indol-3-yl)methyl)phenol (5a) and 3-((1H-indol-3-yl)(pyridin-3-yl)methyl)-1H-indole (5d) exhibited potent activity, showing MIC values 6.5–62.5 μg/mL against Gram positive and Gram negative bacteria. Hemolytic assay of these active DIM derivatives did not show considerable toxic effect on the normal human erythrocytes.     

Effects of sensory modality on cerebral blood flow velocity during vigilance

Transcranial Doppler sonography was used to measure cerebral blood flow velocity (hemovelocity, CBFV) from the left and right middle cerebral arteries during the performance of 40-min auditory and visual vigilance tasks. Reductions in stimulus duration were the critical signals for detection in both tasks, which were equated for stimulus salience and discrimination difficulty. Signal detection responses (correct detections and false alarms) and CBFV declined significantly over time in a linear manner for both modalities. In addition, the overall level of CBFV and the temporal decline in this measure were greater in the right than the left cerebral hemisphere. The results are consistent with the view that a right hemispheric system is involved in the functional control of vigilance and that this system operates in a similar manner in the auditory and visual channels.