Masking of Figure-Ground Texture and Single Targets by Surround Inhibition: A Computational Spiking Model

A visual stimulus can be made invisible, i.e. masked, by the presentation of a second stimulus. In the sensory cortex, neural responses to a masked stimulus are suppressed, yet how this suppression comes about is still debated. Inhibitory models explain masking by asserting that the mask exerts an inhibitory influence on the responses of a neuron evoked by the target. However, other models argue that the masking interferes with recurrent or reentrant processing. Using computer modeling, we show that surround inhibition evoked by ON and OFF responses to the mask suppresses the responses to a briefly presented stimulus in forward and backward masking paradigms. Our model results resemble several previously described psychophysical and neurophysiological findings in perceptual masking experiments and are in line with earlier theoretical descriptions of masking. We suggest that precise spatiotemporal influence of surround inhibition is relevant for visual detection

‘Two Pains Together’: Patient Perspectives on Psychological Aspects of Chronic Pain while Living with HIV

Chronic pain is common in HIV-infected individuals. Understanding HIV-infected patients' chronic pain experience not just from a biological, but also from a psychological perspective, is a critical first step toward improving care for this population. Our objective was to explore HIV-infected patients' perspectives on psychological aspects of chronic pain using in-depth qualitative interviews.Investigators engaged in an iterative process of independent and group coding until theme saturation was reached.Of the 25 patients with chronic pain interviewed, 20 were male, 15 were younger than age 50, and 15 were African-American. Key themes that emerged included the close relationship between mood and pain; mood and pain in the context of living with HIV; use of alcohol/drugs to self-medicate for pain; and the challenge of receiving prescription pain medications while dealing with substance use disorders.The results suggest that psychological approaches to chronic pain treatment may be well received by HIV-infected patients