Self-report depressive symptoms do not directly predict suicidality in nonclinical individuals: Contributions toward a more psychosocial approach to suicide risk

Although suicidality is associated with mental illness in general and depression in particular, many depressed individuals do not attempt suicide and some individuals who attempt to or do die by suicide do not present depressive symptoms. This article aims to contribute to a more psychosocial approach to understanding suicide risk in nonclinical populations. In advocating a psychosocial perspective rather than a depression-focused approach, this article presents four diverse studies that demonstrate sampling and measurement invariance in findings across different populations and specific measures. Study 1 tests the mediation effects of 2 interpersonal variables, thwarted belongingness and perceived burdensomeness, in the association between depressive symptoms and recent suicidality. Studies 2 and 3 evaluate the contribution of hopelessness and psychache, beyond depressive symptoms, to suicidality. Study 4 tests the contribution of life events behind depressive symptoms, and other relevant sociodemographic and clinical variables, to the estimation of “future suicidality.” Overall, results demonstrate that depressive symptoms do not directly predict suicidality in nonclinical individuals, but that other psychosocial variables mediate the association between depressive symptoms and suicidality or predict suicidality when statistically controlling for depressive symptoms. The article contributes to understanding some of the nonpsychopathological factors that potentially link depressive symptoms to suicide risk and that might themselves contribute to suicidality, even when controlling for depressive symptoms.

Detection of Glass pattern configurations by the primary visual cortex

The neurons in the primary visual cortex that respond to the orientation of visual stimuli were discovered in the late 1950s (Hubel, D.H. & Wiesel, T.N. 1959. J. Physiol. 148:574-591) but how they achieve this response is poorly understood. Recently, experiments have demonstrated that the visual cortex may use the image processing techniques of cross or auto-correlation to detect the streaks in random dot patterns (Barlow, H. & Berry, D.L. 2010. Proc. R. Soc. B. 278: 2069-2075). These experiments made use of sinusoidally modulated random dot patterns and of the so-called Glass patterns - where randomly positioned dot pairs are oriented in a parallel configuration (Glass, L. 1969. Nature. 223: 578-580). The image processing used by the visual cortex could be inferred from how the threshold of detection of these patterns in the presence of random noise varied as a function of the dot density in the patterns. In the present study, the detection thresholds have been measured for other types of patterns including circular, hyperbolic, spiral and radial Glass patterns and an indication of the type of image processing (cross or auto-correlation) by the visual cortex is presented. As a result, it is hoped that this study will contribute to an understanding of what David Marr called the ‘computational goal’ of the primary visual cortex (Marr, D. 1982. Vision: A Computational Investigation into the Human Representation and Processing of Visual Information. New York: Freeman.)