ABSTRACT
The polarization of the illumination beam in a beam scanning microscope such as the confocal microscope plays an important role in extracting the orientational information of the molecules in the specimen. In this paper, we present the development of a beam scanning microscope comprising a custom designed optical arrangement to obtain images of the same target with different polarizations of the illumination beam. The optical arrangement, based on a ferroelectric liquid crystal spatial light modulator (FELCSLM), can generate homogeneous as well as non-homogeneous user defined polarization profiles over the cross-sectional area of the illumination beam. Here, we employ a computer generated holography technique and exploit the programmability of the FELCSLM display to considerably reduce the time gap between two successive illuminations of each location of the specimen with two different polarizations. We demonstrate the working of the beam scanning microscope where the polarization profile of the illumination beam is switched at the end of every line scanned, in contrast to a conventional beam scanning microscope where the polarization can be switched at the end of every frame scanned. Preliminary experimental results obtained using a polarization sensitive target confirm the feasibility of the proposed scheme.
ABSTRACT
BACKGROUND AND PURPOSE: Strokes caused by lesions to certain brain areas are associated with poor outcome, which is important both prognostically and to understand the neural basis for recovery. However, lesion anatomy associations with outcome may occur because of effects on baseline severity rather than because of effects on recovery per se. Here, all common stroke locations were surveyed to determine the strongest lesion anatomy associations separately for baseline functional severity and proportional recovery. Since most recovery occurs early, the focus here is on functional changes over the first week. METHOD: Global functional scores (National Institutes of Health Stroke Scale) at baseline and proportional recovery over 1 week were derived from the records of 550 ischaemic stroke patients and related to magnetic resonance imaging lesion location using voxel-lesion mapping. The effects of lesions extending over more than one location were also considered. Cross-validation estimated the percentage of recovery rate variance (r(2) ) accountable by lesion location information. RESULTS: High baseline severity was associated with lesions to the left capsule, striatum and thalamocortical white matter, whereas high recovery rate was associated with lesions to more superficial left fronto-temporal areas. Low recovery rates were associated with lesions to bilateral parietal, right insula, medial frontal, capsule and brainstem. Inclusion of these regions into a multivariate model of proportional recovery rate increased r(2) from 8% to 45%. CONCLUSION: The strongest stroke lesion location associations with 1-week recovery were identified, and it was shown that anatomical information accounts for a sizeable proportion of early recovery variability.
