White matter integrity, as measured by diffusion tensor imaging, distinguishes between impaired and unimpaired older adult decision-makers: A preliminary investigation.

In the context of normal ageing, some individuals experience cognitive changes that affect their decision-making abilities. We investigated whether such cognitive changes could be related to the integrity of cortical white matter, as measured by diffusion tensor imaging (DTI). Participants were administered a well-validated laboratory decision-making task, and were subsequently grouped as either poor decision-makers (older-impaired, n = 9) or strong decision-makers (older-unimpaired, n = 7). Participants also underwent magnetic resonance imaging (MRI) that collected high-resolution structural images, including DTI of the brain. The key variable of interest to be contrasted between the groups was fractional anisotropy (FA), as calculated from the tensor images. We hypothesised that FA values would be lower (indicating poorer integrity of tracts) in the older-impaired participants. The results supported our hypothesis, indicating significant differences in FA values between the participant groups for the entire brain as well as several subregions. The results suggest that poorer decision-making abilities are associated with the integrity of cortical white matter across multiple regions of the brain, and support the call for additional research in this area.

Video enhanced laser scanning microscopic analysis of DNA comet formation.

Laser Scanning Microscopy is a sensitive tool that provides a unique method of analyzing biological systems. Coupled with the Single Cell Gel assay, it allows for accurate and reproducible detection of DNA strand breaks. An understanding of the theory of DNA comet formation is lacking. Using dexamethasone induced apoptosis in murine thymocytes as a model for double strand breaks, we used video enhanced laser scanning microscopy to evaluate the leading edge of DNA migration in the single cell gel assay. In this system, comet length increases significantly within the first thirty seconds of electrophoresis, the greatest increase in length is completed within the first minute, and the first two minutes are important in significant increases in DNA migration during DNA comet formation.