Dysregulation of visual motion inhibition in major depression. (30th June 2016)

• Record Type: Journal Article
• Authors: Norton, Daniel J.; McBain, Ryan K.; Pizzagalli, Diego A.; Cronin-Golomb, Alice; Chen, Yue
• Is Part Of: Psychiatry research. Volume 240(2016)
• Page Start: 214
• Page End: 221
• Publication Date: 2016-06-30
• Subjects: Cognitive -- Neuroscience -- Motion -- Vision -- Center surround -- Depression -- Psychophysics -- Mood; Psychiatry -- Periodicals; Psychiatry -- periodicals; Psychiatrie -- Périodiques; 616.89
• DOI: 10.1016/j.psychres.2016.04.028
• Languages: English
• ISSNs: 0165-1781

Abstract

Abstract: Individuals with depression show depleted concentrations of the inhibitory neurotransmitter GABA in occipital (visual) cortex, predicting weakened inhibition within their visual systems. Yet, visual inhibition in depression remains largely unexplored. To fill this gap, we examined the inhibitory process of center-surround suppression (CSS) of visual motion in depressed individuals. Perceptual performance in discriminating the direction of motion was measured as a function of stimulus presentation time and contrast in depressed individuals (n=27) and controls (n=22). CSS was operationalized as the accuracy difference between conditions using large (7.5°) and small (1.5°) grating stimuli. Both depressed and control participants displayed the expected advantage in accuracy for small stimuli at high contrast. A significant interaction emerged between subject group, contrast level and presentation time, indicating that alterations of CSS in depression were modulated by stimulus conditions. At high contrast, depressed individuals showed significantly greater CSS than controls at the 66 ms presentation time (where the effect peaked in both groups). The results' specificity and dependence on stimulus features such as contrast, size and presentation time suggest that they arise from changes in early visual processing, and are not the results of a generalized deficit or cognitive bias. Highlights: Depleted occipital GABA levels in depression predict weakened visual inhibition. The present study is the first to measure visual inhibition in depression. Visual inhibition was defined as center surround suppression (CSS) of visual motion. Surprisingly, depressed individuals showed increased CSS under certain conditions. The results' specificity implicate changes early in the visual system.