Assessment of magno-, parvo-, and koniocellular visual streams in migraine / by James Brazeau.

Although visual abnormalities have been noted in migraine, no studies have specifically sought to assess all three visual processing streams. We are the first to psychophysically assess visual functionality of the magnocellular (MC), parvocellular (PC), and koniocellular (KC) parallel streams at different hierarchical visual pathway loci across groups of individuals with migraine with aura (MA; n = 13), migraine without aura (MWO; n = 14), and controls (o = 15). Participants completed four tasks: (I) visual field analysis using short-wave length automated perimetry (SWAP), (2) chromatic discrimination along cone-excitation axes using the Cambridge Colour Test, (3) chromatic contrast sensitivity across isoluminant bichromatic spatial Gabor gratings, and (4) luminance contrast sensitivity across heteroluminant spatial Gabor gratings. Our results suggest that deficits are selective to short-wavelength-sensitive cones and the associated KC visual stream. Furthermore, functional inconsistencies and consistencies between our SWAP and chromatic discrimination measures and SWAP and chromatic sensitivity measures, respectively, provide evidence for a retinal locus of dysfunction in MA that is compensated for at downstream locations within the KC visual stream

Psychological and physiological predictors of the development and modulation of instrusive images

Researchers have suggested that engaging in visuospatial tasks, such as the videogame Tetris™, following a trauma may interfere with the development of intrusive images associated with posttraumatic stress disorder (PTSD). The present study attempted to replicate this finding using a trauma film paradigm. Furthermore, we were interested in identifying if participants who played Tetris would show changes in other symptoms associated with PTSD, such as enhanced startle responses. Participants (N = 129) were asked to view a film with traumatic content and were then randomly assigned to play either Tetris or to sit quietly for 10 min. Psychological reactivity (positive affect, negative affect, and dissociation) and physiological reactivity (cardiac measure of sympathetic and parasympathetic activity, heart rate, and salivary alpha amylase) were examined as potential predictors of the frequency of intrusive images. Our findings indicated that intrusive images occurred significantly less often amongst individuals assigned to the Tetris game-play condition. We were able to identify that the frequency of intrusive images was modulated by patterns of sympathetic arousal, dissociation, and affective reactivity. Furthermore, our results indicated that individuals who engaged in the Tetris task showed a heightened startle response to aversive material. These findings are discussed in terms of their relevance to etiological models, and the prevention of PTSD

Understanding the retinal basis of vision across species

The vertebrate retina first evolved some 500 million years ago in ancestral marine chordates. Since then, the eyes of different species have been tuned to best support their unique visuoecological lifestyles. Visual specializations in eye designs, large-scale inhomogeneities across the retinal surface and local circuit motifs mean that all species' retinas are unique. Computational theories, such as the efficient coding hypothesis, have come a long way towards an explanation of the basic features of retinal organization and function; however, they cannot explain the full extent of retinal diversity within and across species. To build a truly general understanding of vertebrate vision and the retina's computational purpose, it is therefore important to more quantitatively relate different species' retinal functions to their specific natural environments and behavioural requirements. Ultimately, the goal of such efforts should be to build up to a more general theory of vision

Examen préliminaire d’un traitement axé sur les forces destiné aux adolescents ayant des troubles liés à la toxicomanie

Adolescent substance use disorders are a major public health concern. Given the many challenges associated with treating this population, ongoing research in this area is imperative. The purpose of the current study was to provide a preliminary examination of the substance use outcomes associated with an adolescent residential treatment program that utilizes a strengths-based approach. The current study examined treatment outcomes in 61 adolescents (aged 14 to 18 years) who completed a 5-week strengths-based residential treatment program for adolescent substance use issues. Results showed significant reductions in frequency of alcohol and marijuana use from pretreatment to 3 and 6 months posttreatment, and in opioid use frequency from pretreatment to 3 months posttreatment. In addition, changes in self-reported substance use goal progress scores indicated significant improvements in goal progress from pretreatment to 3 months posttreatment; these improvements were maintained at 6 months posttreatment. Finally, depressive symptomology was also found to decrease significantly from pretreatment to posttreatment, and this decrease was found to be predictive of better substance use outcomes at 6 months posttreatment. These findings add to the literature by providing preliminary data that support the utility of the strengths-based approach in the treatment of adolescence substance use issues.La toxicomanie chez les adolescents représente un enjeu majeur en santé publique. Étant donné les nombreux défis que comporte le traitement de cette population, la recherché continue en ce domaine est indiquée. La présente étude a pour objet de fournir un examen préliminaire des effets sur la consommation de substances illicites en lien avec un programme de traitement résidentiel de la toxicomanie chez des adolescents, qui mise sur une approche axée sur les forces. L’étude en cause a porté sur les résultats du traitement chez 61 adolescents (âgés de 14 à 18 ans) qui ont terminé un programme résidentiel de traitement de 5 semaines axé sur les forces et conçu pour des adolescents ayant des troubles liés à la toxicomanie. Les résultats ont révélé des réductions significatives dans la fréquence de consommation d’alcool et de marijuana lorsqu’on compare les periods antérieure au traitement et postérieure de 3 à 6 mois; on a observé des résultats similaires pour la fréquence de consommation d’opioïdes lorsqu’on compare les périodes antérieure au traitement et postérieure de 3 mois. De plus, d’après les résultats de réalisation des objectifs de consommation rapportés par les participants, on a noté des ameliorations significatives lorsqu’on compare les périodes antérieure au traitement et postérieure de 3 mois, et ces améliorations se sont maintenues pour la période de 6 mois suivant le traitement. Enfin, on a aussi observé une diminution significative des symptômes de depression entre les périodes antérieure et postérieure au traitement, et cette diminution permettait de prédire de meilleurs résultats quant à la consommation pendant la période de 6 mois suivant le traitement. Ces observations viennent enrichir la littérature en fournissant des données préliminaires appuyant l’utilité de l’approche axée sur les forces pour le traitement des troubles liés à la toxicomanie chez les adolescents