DOI: 10.5281/zenodo.3479557
title: Midlevel Visual Deficits after Strokes Involving Area Human V4

description: <strong><em>ScreeningMaster.exe</em></strong> <strong>Program is written in C/C++ and is part of a proprietary framework developed in our lab that was used for stimulus generation under the name of 'SING' to generate a multitude of psychophysical stimuli for more than 20 years. The version downloaded contains the parameters specific tor the stimuli used in our present patient study.</strong> <strong>.cfg</strong> <strong>contains the configuration for the stimuli globally (detection or discrimination) and specifically for the setup of the stimuli: </strong> <strong>for luminance contrast detection/discrimination (=SETUP[Kontrast {QuadFormDots}])</strong> <strong>for texture detection/discrimination (=SETUP[Orientierung {QuadFormTex}])</strong> <strong>for motion detection/discrimination (=SETUP[Bewegungsrichtung {QuadFormMove}])</strong> <strong>for colour detection/discrimination (=SETUP[Farbe (Farbwert) {QuadFormIshihara}])</strong> <strong>.idv</strong> <strong>is the program to analyze the threshold of the staircase per quadrant<em>.</em></strong> <strong><em>For more information consult the material and methods in the paper.</em></strong> <strong>psychophysics_rawdata_zenodo.xlsx</strong>: Psychophysical data of the complete dataset (patients and controls). 51 patients (category 1) are presented in the paper, this subgroup of the 128 patients. Patients were chosen based on the site of lesion according to the following criteria: unilateral lesion of the occipital and/or temporal and/or parietal cortex; lesion onset older than two months; no aphasia; no neglect (tested by three paper and pencil tests); no dementia; no visual field defects within the central 10 degrees in standard perimetry; no psychiatric or ophthalmological disorders. In addition, luminance contrast detection in the target quadrant had to be within normal limits. Controls (N=61) were included if they reported no neurological, psychiatric, or ophthalmological disturbances. All subjects had normal or corrected to normal visual acuity. For both conditions (localisation based on detection or else (form) discrimination) perceptual thresholds (62.5 % correct responses) were defined in each experimental run for each visual field quadrant using the adaptive staircase procedure QUEST (Quick Estimation by Sequential Testing; Watson & Pelli, 1983) yielding separate threshold values for each quadrant. After a short training with some clearly suprathreshold presentations the sequence of the four independent staircases was organized in randomized order within each experimental run. Subjects completed 30 trials per visual field quadrant, i.e. 120 trials per run. Each visual submodality (luminance, texture, motion, and colour) and task (shape localisation based on detection vs. form discrimination) was tested in a separate run. The sequence of tasks was held constant across subjects. Subjects first performed the shape localisation tasks based on detection in the order luminance, texture, motion, and colour. Subsequently the shape localisation tasks based on form discrimination were conducted in the same order. <strong>Data analysis</strong> Controls were divided into three age groups: 20-39 yrs., 40-59 yrs., and 60+ yrs. of about equal size. Individual patient’s results were compared to the corresponding age group. <strong>Logarithmization, normalization</strong> As the expected psychophysical response distributions especially for contrast and motion vision follow a logarithmic characteristic, we logarithmized all results of controls and patients.In addition, in order to correct for age we normalized each individual threshold by the following equation: Threshold norm= threshold individual - mean threshold age-matched controls/ SD age-matched controls The mean thresholds of the age matched controls are defined as the mean of the four quadrants of the visual field. An individual normalized threshold represents the number of standard deviations (SD) from the age mean. We define more than three SD’s above the mean of controls as pathological. <strong>Topographical sequencing</strong> We first defined for each patient the visual field quadrant expected to be most affected based on the position of the lesion in the MRI/CT scan. Depending on the side and whether the lesion was above or below the calcarine fissure, we chose the contra-lesional visual field and either the lower or else upper (contra-lesional) quadrant of the visual field. This quadrant was considered the target quadrant (QI). Its companion on the same (contra-lesional) side was QII since we expected deficits to spread on the same cortical hemisphere more than to the opposite side. The quadrant mirror-symmetrical to QI was defined as QIII since it is connected to QI via callosal fibres. The quadrant least expected to show deficits in visual <strong>LogData_zenodo.xlsx:</strong> Logarithmized, normalized data and topographical sequenced SD values of patients category 1 and controls.