New paper in Vision Research

First- and second-order contrast sensitivity functions reveal disrupted visual processing following mild traumatic brain injury.

Spiegel, D. P., Reynaud, A., Ruiz, T., Laguë-Beauvais, M., Hess, R., & Farivar, R.

Vision is disrupted by traumatic brain injury (TBI), with vision-related complaints being amongst the most common in this population. Based on the neural responses of early visual cortical areas, injury to the visual cortex would be predicted to affect both 1(st) order and 2(nd) order contrast sensitivity functions (CSFs)-the height and/or the cut-off of the CSF are expected to be affected by TBI. Previous studies have reported disruptions only in 2(nd) order contrast sensitivity, but using a narrow range of parameters and divergent methodologies-no study has characterized the effect of TBI on the full CSF for both 1(st) and 2(nd) order stimuli. Such information is needed to properly understand the effect of TBI on contrast perception, which underlies all visual processing. Using a unified framework based on the quick contrast sensitivity function, we measured full CSFs for static and dynamic 1(st) and 2(nd) order stimuli. Our results provide a unique dataset showing alterations in sensitivity for both 1(st) and 2(nd) order visual stimuli. In particular, we show that TBI patients have increased sensitivity for 1(st) order motion stimuli and decreased sensitivity to orientation-defined and contrast-defined 2(nd) order stimuli. In addition, our data suggest that TBI patients' sensitivity for both 1(st) order stimuli and 2(nd) order contrast-defined stimuli is shifted towards higher spatial frequencies.

Spiegel, D. P., Reynaud, A., Ruiz, T., Laguë-Beauvais, M., Hess, R., & Farivar, R. (2016). First- and second-order contrast sensitivity functions reveal disrupted visual processing following mild traumatic brain injury. Vision Research, 122, 43–50. PDF

Averaged CSFs (top row) and model estimates based on the group pseudomedian estimates of qCSF parameters (bottom row). Averaged CSFs represent geometric mean with shading representing the standard deviation. Left panels TBI group; right panels normative dataset. cpd = cycles per degree. 1st Ori – 1st order orientation, 1st Mot – 1st order motion, 2nd Ori – 2nd order orientation modulation, 2nd Mot – 2nd order motion modulation, 2nd Cont – 2nd order contrast modulation. 

Averaged CSFs (top row) and model estimates based on the group pseudomedian estimates of qCSF parameters (bottom row). Averaged CSFs represent geometric mean with shading representing the standard deviation. Left panels TBI group; right panels normative dataset. cpd = cycles per degree. 1st Ori – 1st order orientation, 1st Mot – 1st order motion, 2nd Ori – 2nd order orientation modulation, 2nd Mot – 2nd order motion modulation, 2nd Cont – 2nd order contrast modulation.