Pouget and driver 2000

Hence, our lateralized saliency modification induced a neglect-like behavior not only at the very beginning but also during the early saliency-driven phase of attentional orienting in the visual scene.

When focusing our analysis on the outmost parts of the visual scene, another effect of the saliency modification emerged and this was even evident over the whole time range of stimulus presentation. To specify, despite the strong top-down control during visual search, the saliency modification could again induce a clear rightward shift of the very first orienting, suppression of the common leftward bias at the early phase of scene exploration and a preference to explore the outer right over the outer left part of the visual scene.

That the process of selective attention was also disturbed during goal-driven visual search argues for a successful alteration of the attentional priority map which is known to integrate both bottom-up and top-down signals Fecteau and Munoz, Our findings are in accordance with a previous study that recorded eye movements while patients with left hemispatial neglect explored an abstract, non-naturalistic visual stimulus Bays et al.

The authors interpreted their findings as consistent with the concept of an attentional priority map that is damaged in patients with parietal lesions and hemispatial neglect Pouget and Driver, ; Bays et al.

The results of our virtual disease model corroborate this concept. Our findings further provide empirical evidence for a previously suggested computerized lesion model of spatial neglect Pouget and Sejnowski, The authors argue that damage to the parietal lobe may induce a gradient in the representation of objects in space and could explain many of the behavioral deficits in patients with hemispatial neglect Pouget and Sejnowski, However, an unbalanced attentional priority map, as proposed by the studies mentioned and supported by our study, cannot fully account for all the behavioral deficits that patients with the full-blown clinical picture of neglect exhibit.

This underlines the heterogeneous nature of spatial neglect as a multi-component syndrome which cannot be fully explained by one pathophysiological account or lesion model Parton et al. There are different possible explanations: first, our saliency modification might not have been strong enough to elicit such a pronounced shift of the center of fixation. However, we could not further increase the physical properties of the masks i.

Thus, an increase of the saliency mask would have gone on the expense of their rather subliminal nature, which was crucial to creating a neglect-like unawareness of the deficit. The second explanation refers to the different pathophysiological concepts of the ipsilesional oculomotor bias in neglect patients. Karnath has argued that the ipsilesional shift of the center of fixation is not due to an attentional deficit but to a disturbed transformation of multimodal sensory signals into the topographic map of space in the damaged brain of neglect patients Karnath and Fetter, ; Karnath, This alleged conflict between an attentional and transformational account was partly reconciled by the concept of parietal neurons integrating attention-relevant bottom-up and top-down signals into one representational map of space Pouget and Driver, The finding underlines the proposal that the ipsilesional attention bias found in patients with hemispatial neglect arises from an imbalanced attentional priority map that integrates bottom-up and top-down signals into one topographic representation of objects in space by use of different egocentric spatial reference frames Pouget and Driver, ; Pouget and Sejnowski, Furthermore, that such a modification of the sensory visual input is able to induce behavioral changes visuospatial exploration , supports the conceptual view of the attentional priority map in the parietal lobe as an interface between perception and action Gottlieb, ; Bisley and Goldberg, ; Ptak and Fellrath, We imagine at least two potential future applications of our gaze-contingent approach.

We, therefore, share our original code see Supplementary Material Data Sheet S1 which may be refined by other researchers in the field to induce changes in exploratory eye movements of healthy subjects that get even closer to those of neglect patients. Second, the gaze-contingent approach could be applied in a modified version as a therapeutic intervention during neglect rehabilitation.

Therefore, the mask would be mirrored in order to relatively increase the saliency of objects in the contralesional left hemifield while objects in the ipsilesional right hemifield would be attenuated in their attentional weight. Such an intervention during a visual exploration training in patients with hemispatial neglect could potentially counterbalance the ipsilesional attention bias and concomitant rightward shift of exploratory EM in left hemispatial neglect, which might help to reduce functional consequences and neglect-related disability.

The datasets generated for this study are available from the corresponding author upon reasonable request. BM wrote the first draft of the manuscript. All authors contributed to manuscript revision, read and approved the submitted version. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Andersen, R. Encoding of spatial location by posterior parietal neurons.

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