Altered white matter connectivity associated with visual hallucinations following occipital stroke

Introduction: Visual hallucinations that arise following vision loss stem from aberrant functional activity in visual cortices and an imbalance of activity across associated cortical and subcortical networks subsequent to visual pathway damage. We sought to determine if structural changes in white matter connectivity play a role in cases of chronic visual hallucinations associated with visual cortical damage. Methods: We performed diffusion tensor imaging (DTI) and probabilistic fiber tractography to assess white matter connectivity in a patient suffering from continuous and disruptive phosphene (simple) visual hallucinations for more than 2 years following right occipital stroke. We compared these data to that of healthy age-matched controls. Results: Probabilistic tractography to reconstruct white matter tracts suggests regeneration of terminal fibers of the ipsilesional optic radiations in the patient. However, arrangement of the converse reconstruction of these tracts, which were seeded from the ipsilesional visual cortex to the intrahemispheric lateral geniculate body, remained disrupted. We further observed compromised structural characteristics, and changes in diffusion (measured using diffusion tensor indices) of white matter tracts in the patient connecting the visual cortex with frontal and temporal regions, and also in interhemispheric connectivity between visual cortices. Conclusions: Cortical remapping and the disruption of communication between visual cortices and remote regions are consistent with our previous functional magnetic resonance imaging (fMRI) data showing imbalanced functional activity of the same regions in this patient (Rafique et al, 2016, Neurology, 87, 1493–1500). Long-term adaptive and disruptive changes in white matter connectivity may account for the rare nature of cases presenting with chronic and continuous visual hallucinations.York University Librarie

Forms of Dissent

Literature, Satire, and the Early Stuart State (Andrew McRae) The English Radical Imagination: Culture, Religion, and Revolution, 1630–1660 (Nicholas McDowell

Understanding the Aboriginal/Non-Aboriginal Gap in Student Performance: Lessons From British Columbia

There exist very large gaps between Aboriginal and non-Aboriginal student performance in most B.C. schools. However, Aboriginal students in some school districts perform remarkably well. What are these districts doing right? The authors draw lessons that may well apply across Canada.social policy, socioeconomic conditions, Aboriginal education, British Columbia

Identifying the Processes of Teacher Application and Adoption of a Novel Instructional Strategy

Research on adolescent learning shows that students learn best when they are actively engaged with the content and when metacognitive teaching strategies are employed. Despite these findings, current studies show that most classrooms are still teacher centered and that passive learning strategies are the norm. To help teachers incorporate highly effective instructional strategies into their classrooms countless professional development workshops are offered each; yet most of these workshops fail to effect true change in the classroom behavior of teachers. The design of this study compares teachers’ attempts to employ new instructional strategies within the context of a model curriculum with subsequent attempts to employ those same strategies outside of the model. The purposes of this study were to: (1) investigate how teachers apply new knowledge, attitudes, or behaviors and adopt them as a regular part of their instructional process; (2) identify barriers to instructional change; and (3) examine the impact of a research-based professional development model on teachers’ use of a novel instructional strategy. The results of this study indicate that teachers need to understand the educational theory behind new strategies, see the strategy modeled for them, be provided with opportunities to discuss the strategy as it relates to their classrooms and current instructional practices, and have on-site support when implementing the strategy on their own

Quantitative Comparison of Plant Community Hydrology Using Large-Extent, Long-Term Data

Large-extent vegetation datasets that co-occur with long-term hydrology data provide new ways to develop biologically meaningful hydrologic variables and to determine plant community responses to hydrology. We analyzed the suitability of different hydrological variables to predict vegetation in two water conservation areas (WCAs) in the Florida Everglades, USA, and developed metrics to define realized hydrologic optima and tolerances. Using vegetation data spatially co-located with long-term hydrological records, we evaluated seven variables describing water depth, hydroperiod length, and number of wet/dry events; each variable was tested for 2-, 4- and 10-year intervals for Julian annual averages and environmentally-defined hydrologic intervals. Maximum length and maximum water depth during the wet period calculated for environmentally-defined hydrologic intervals over a 4-year period were the best predictors of vegetation type. Proportional abundance of vegetation types along hydrological gradients indicated that communities had different realized optima and tolerances across WCAs. Although in both WCAs, the trees/shrubs class was on the drier/shallower end of hydrological gradients, while slough communities occupied the wetter/deeper end, the distribution ofCladium, Typha, wet prairie and Salix communities, which were intermediate for most hydrological variables, varied in proportional abundance along hydrologic gradients between WCAs, indicating that realized optima and tolerances are context-dependent