Motion and form coherence processing in individuals with cerebral visual impairment

Abstract

AimUsing a visual psychophysical paradigm, we sought to assess motion and form coherence thresholds as indices of dorsal and ventral visual stream processing respectively, in individuals with cerebral visual impairment (CVI). We also explored potential associations between psychophysical assessments and brain lesion severity in CVI.MethodTwenty individuals previously diagnosed with CVI (mean age = 17 years 11 months [SD 5 years 10 months]; mean Verbal IQ = 86.42 [SD 35.85]) and 30 individuals with neurotypical development (mean age = 20 years 1 month [SD 3 years 8 months]; mean Verbal IQ = 110.05 [SD 19.34]) participated in the study. In this two‐group comparison, cross‐sectional study design, global motion, and form pattern coherence thresholds were assessed using a computerized, generalizable, self‐administrable, and response‐adaptive psychophysical paradigm called FInD (Foraging Interactive D‐prime).ResultsConsistent with dorsal stream dysfunction, mean global motion (but not form) coherence thresholds were significantly higher in individuals with CVI compared to controls. No statistically significant association was found between coherence thresholds and lesion severity.InterpretationThese results suggest that the objective assessment of motion and form coherence threshold sensitivities using this psychophysical paradigm may be useful in helping to characterize perceptual deficits and the complex clinical profile of CVI.

Rapid measurement and machine learning classification of colour vision deficiency

“…FInD is rapid, self-administered and easy to use, without strict operating regulations other than the normal use of a computer, and so can be readily grasped by patients (including children). 14 The combination of colour detection and colour discrimination performance also provides richer information about colour perception in CVDs, and enables classification of colour vision subtypes using unsupervised machine learning classification. In comparison, the HRR test, although rapid and easy, provides limited information about atypical colour perception, and is not able to classify CVD type for very mild cases (CVD#7).…”

“…FInD uses an adaptive algorithm that measures visual performance thresholds for a wide range of visual functions, for example, contrast sensitivity, motion and form coherence. 13,14 The algorithm selects stimulus strength derived from d′, a signal-to-noise ratio metric referring to the detectability of the stimulus and calculates a new d′ based on previous responses.…”

Visual search patterns during exploration of naturalistic scenes are driven by saliency cues in individuals with cerebral visual impairment

“…All CVI participants were previously diagnosed prior to participating in this study by eyecare professionals with extensive clinical experience working with this population (see 68 for similar criteria regarding the diagnosis of CVI). Briefly, the diagnosis was based on a directed and objective assessment of visual functions (including visual acuity, contrast, visual field perimetry, color, and ocular motor functions), functional vision assessment (use of structured questionnaires, surveys, and activities 69 – 71 , a comprehensive refraction and ocular examination, as well as an integrated review of medical history and available neuroimaging and electrophysiology records (see also 20 , 72 , 73 for similar criteria and protocol).…”

Visual Search Patterns During Exploration of Naturalistic Scenes are Driven by Saliency Cues in Individuals with Cerebral Visual Impairment

“…A total of 31 individuals participated in the study, with roughly an equal distribution of control (n = 16) and CVI participants (n = 15). All participants with CVI were previously diagnosed by eyecare professionals with extensive clinical experience working with this population (see 54 for further details regarding diagnosis of CVI). Brie y, the diagnosis was based on a directed and objective assessment of visual functions (including visual acuity, contrast, visual eld perimetry, color, and ocular motor functions), functional vision assessment (use of structured questionnaires, surveys, and activities), a thorough refractive and ocular examination, as well as an integrated review of medical history and available neuroimaging and electrophysiology records 22,55,56 .…”