September 2015
Volume 15, Issue 12
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2015
Factor analysis of individual differences in retinal (PERG) and cortical (VEP) visual contrast responses reveals two retinal and two cortical processes in adults with and without depression.
Author Affiliations
  • David Peterzell
    Clinical Psychology, John F. Kennedy University, Pleasant Hill, California USA
  • Emanuel Bubl
    Department of Psychiatry and Psychotherapy, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
  • Michael Bach
    University Eye Hospital, Albert-Ludwigs-University of Freiburg, Freiburg, Germany
Journal of Vision September 2015, Vol.15, 1005. doi:10.1167/15.12.1005
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      David Peterzell, Emanuel Bubl, Michael Bach; Factor analysis of individual differences in retinal (PERG) and cortical (VEP) visual contrast responses reveals two retinal and two cortical processes in adults with and without depression.. Journal of Vision 2015;15(12):1005. doi: 10.1167/15.12.1005.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Recent studies of contrast response functions have found: 1) Separate cortical processes mediate amplitudes at high and low contrasts, as revealed by principal component analysis (PCA) of individual differences in visual evoked potentials (VEPs) (Hamer, Souza et al. 2013). 2) There is a strong reduction in contrast perception and retinal contrast gain in patients with major depression, which normalizes after antidepressive therapy and remission of depression (Bubl et al. 2009; 2010; 2012). The current analysis examines processes (statistical factors) underlying cortical and retinal contrast response functions. Further, it examines which of these processes change with depression. Thirty-five patients with a diagnosis of major depression (26 with and 9 without medication) and 21 healthy subjects participated. Pattern electroretinograms (PERGs) were recorded from both eyes. To quantify PERG and VEP based contrast responses, a sequence of five checkerboard stimuli was presented with 0.5° check size, contrast-reversing at 12 reversals per second, and Michelson contrasts of 3.2%, 7.3%, 16.2%, 36%, and 80%. Individual differences in left and right eye responses were highly intercorrelated, and thus averaged. Principal components were computed from log amplitudes and rotated to approximate simple structure using a Varimax rotation. (1) Two retinal (PERG) and two cortical (VEP) factors were found. The two cortical processes mediate high and low contrasts, consitent with Hamer et al. The two retinal factors also mediate high and low contrasts, but are independent of (uncorrelated with) cortical factors. The four factors were distinct from three additional factors found for VEP noise and PERG noise in left and right eyes. (2) The only factor of the four that changes significantly with depression is a retinal factor tuned to high contrasts. Our analysis identifies probable contrast-sensitive mechanisms, and shows a surprising independence of retinal and cortical gains. Changes in contrast perception in depression may be linked to a single retinal process.

Meeting abstract presented at VSS 2015

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