Abstract
Background: Occipital cortex lesions (OCLs) typically result in visual field defects (VFDs) contralateral to the damage. VFDs are usually mapped with perimetry involving the detection of point targets. This, however, ignores the important role of integration of visual information across locations in many tasks of everyday life. Here, we ask whether standard perimetry can fully characterize the consequences of OCLs. We compare performance on a rapid scene discrimination task of OCL participants and healthy observers with simulated VFDs. While the healthy observers will only suffer the loss of part of the visual scene, the damage in the OCL participants may further compromise global visual processing.Methods: VFDs were mapped with Humphrey perimetry, and participants performed two rapid scene discrimination tasks. In healthy participants, the VFDs were simulated with hemi- and quadrant occlusions. Additionally, the GIST model, a computational model of scene recognition, was used to make individual predictions based on the VFDs.Results: The GIST model was able to predict the performance of controls regarding the effects of the local occlusion. Using the individual predictions of the GIST model, we can determine that the variability between the OCL participants is much larger than the extent of the VFD could account for. The OCL participants can further be categorized as performing worse, the same, or better as their VFD would predict.Conclusions: While in healthy observers the extent of the simulated occlusion accounts for their performance loss, the OCL participants’ performance is not fully determined by the extent or shape of their VFD as measured with Humphrey perimetry. While some OCL participants are indeed only limited by the local occlusion of the scene, for others, the lesions compromised the visual network in a more global and disruptive way. Yet one outperformed a healthy observer, suggesting a possible adaptation to the VFD. Preliminary analysis of neuroimaging data suggests that damage to the lateral geniculate nucleus and corpus callosum might be associated with the larger disruption of rapid scene discrimination. We believe our approach offers a useful behavioral tool for investigating why similar VFDs can produce widely differing limitations in everyday life.
Highlights
Occipital cortex lesions (OCLs) and/or post-chiasmatic lesions commonly result in the loss of visual sensitivity and blindness contralateral to the damage: a visual field defect (VFD; Zihl, 1994, 2000; Truelsen et al, 2006; Zhang et al, 2006; Celebisoy et al, 2011)
Shows that the VFD cannot fully explain a person’s daily-life limitations (Mueller et al, 2003; Papageorgiou et al, 2007; Gall et al, 2009). This discrepancy indicates that the current clinical practice, to judge ADL limitation in OCL patients primarily based on VFD, may be improved
We explore the potential of simulating their lesions in the spatial envelope model (e.g., GIST model; Oliva and Torralba, 2001), a computational model that summarizes the scene by coarsely filtering the spatial frequency distributions using a global Fourier transformation
Summary
Occipital cortex lesions (OCLs) and/or post-chiasmatic lesions commonly result in the loss of visual sensitivity and blindness contralateral to the damage: a visual field defect (VFD; Zihl, 1994, 2000; Truelsen et al, 2006; Zhang et al, 2006; Celebisoy et al, 2011). These lesions can have severe debilitating consequences, disrupting people’s activities of daily living (ADLs) such as reading, driving, and their work. While the healthy observers will only suffer the loss of part of the visual scene, the damage in the OCL participants may further compromise global visual processing
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