Trans-saccadic priming in hemianopia: sighted-field sensitivity is boosted by a blind-field prime

We experience visual stability despite shifts of the visual array across the retina produced by eye movements. A process known as remapping is thought to keep track of the spatial locations of objects as they move on the retina. We explored remapping in damaged visual cortex by presenting a stimulus in the blind field of two patients with hemianopia. When they executed a saccadic eye movement that would bring the stimulated location into the sighted field, reported awareness of the stimulus increased, even though the stimulus was removed before the saccade began and so never actually fell in the sighted field. Moreover, when a location was primed by a blind-field stimulus and then brought into the sighted field by a saccade, detection sensitivity for near-threshold targets appearing at this location increased dramatically. The results demonstrate that brain areas supporting conscious vision are not necessary for remapping, and suggest visual stability is maintained for salient objects even when they are not consciously perceived

Use of NeuroEyeCoach™ to Improve Eye Movement Efficacy in Patients with Homonymous Visual Field Loss

Acknowledgments The authors would like to thank Sigrid Kenkel, Susanne Muller, Valentina Varalta, Cristina Fonte, Venecia Alb, and Cristina Racasan who have contributed to data collection. Declaration of Interest: AS is Chief Science Officer of NovaVision Inc. NS has no conflict of interest. JZ is a member of the Scientific Advisory Board of NovaVision Inc. This study was supported by a NovaVision Inc. research grant to AS.Peer reviewedPublisher PD

Increased visual sensitivity and occipital activity in patients with hemianopia following vision rehabilitation

Acknowledgements We would like to thank the participants for giving up their time to engage with the research.Peer reviewedPublisher PD

Efficacy and predictors of recovery of function after eye movement training in 296 hemianopic patients

Funding Development of NeuroEyeCoachTM and completion of regulatory requirements were funded by NovaVision Inc and developed by Arash Sahraie and Josef Zihl with the help of a technical team (Insiso Ltd.). Acknowledgements We would like to acknowledge the help of Insiso Ltd., UK for software support and data download. AMHC is supported by a Biotechnology and Biological Sciences Research Council (BBSRC) [grant number BB/J01446X/1] Case Ph.D. Studentship awarded by East of Scotland Bioscience (EastBio) Doctoral Training Partnership in collaboration with NovaVision.Peer reviewedPublisher PD

Some aspects of the pupil response in relation to stimulus movement and colour

Recent investigations have shown that the activity of the visual system in the processing of some stimulus attributes such as spatial structure and stimulus colour are reflected in the pupil response in the form of a small transient constriction at the stimulus onset. The response amplitude appears to be proportional to the level of activity generated and varies systematically with the properties of the visual stimulus. In this report, it has been shown that the processing of coherent motion information can also produce pupillary changes in the form of pupil motion responses (PMRs). The results show that PMRs are present for both foveal and peripheral stimulus presentations and are not affected significantly by degradation of retinal image quality. It has been demonstrated that PMRs are also elicited to sudden changes in stimulus speed and direction, and that the response amplitudes vary systematically with the percentage change involved. There are extensive psychophysical data showing that blindsight subjects are sensitive to movement information when the stimulus is presented in their blind field. In this study, pupillometric parallels for the psychophysical findings have been demonstrated. Data which reveal the existence of residual chromatic discrimination in the absence of VI have also been obtained in two blindsight subjects. It has been shown that their psychophysical performance improves with the level of chromatic saturation of the stimulus. The pupil colour responses have been investigated under similar conditions. Results show that the pupil responses to coloured stimuli can also be elicited in the blind field and that these responses parallel the psychophysical findings. The results obtained have been discussed in relation to the properties of the neuronal structures and visual pathways which are likely to mediate the observed pupillometric and psychophysical findings

Orienting to threat:Faster localization of fearful facial expressions and body postures revealed by saccadic eye movements

Most studies investigating speeded orientation towards threat have used manual responses. By measuring orienting behaviour using eye movements a more direct and ecologically valid measure of attention can be made. Here, we used a forced-choice saccadic and manual localization task to investigate the speed of discrimination for fearful and neutral body and face images. Fearful/neutral body or face pairs were bilaterally presented for either 20 or 500 ms. Results showed faster saccadic orienting to fearful body and face emotions compared with neutral only at the shortest presentation time (20 ms). For manual responses, faster discrimination of fearful bodies and faces was observed only at the longest duration (500 ms). More errors were made when localizing neutral targets, suggesting that fearful bodies and faces may have captured attention automatically. Results were not attributable to low-level image properties as no threat bias, in terms of reaction time or accuracy, was observed for inverted presentation. Taken together, the results suggest faster localization of threat conveyed both by the face and the body within the oculomotor system. In addition, enhanced detection of fearful body postures suggests that we can readily recognize threat-related information conveyed by body postures in the absence of any face cues

Inefficient search strategies in simulated hemianopia.

We investigated whether healthy participants can spontaneously adopt effective eye movement strategies to compensate for information loss similar to that experienced by patients with damage to visual cortex (hemianopia). Visual information in 1 hemifield was removed or degraded while participants searched for an emotional face among neutral faces or a line tilted 45° to the right among lines of varying degree of tilt. A bias to direct saccades toward the sighted field was observed across all 4 experiments. The proportion of saccades directed toward the “blind” field increased with the amount of information available in that field, suggesting fixations are driven toward salient visual stimuli rather than toward locations that maximize information gain. In Experiments 1 and 2, the sighted-field bias had a minimal impact on search efficiency, because the target was difficult to find. However, the sighted-field bias persisted even when the target was visually distinct from the distractors and could easily be detected in the periphery (Experiments 3 and 4). This surprisingly inefficient search behavior suggests that eye movements are biased to salient visual stimuli even when it comes at a clear cost to search efficiency, and efficient strategies to compensate for visual deficits are not spontaneously adopted by healthy participants

Self-relevance prioritizes access to visual awareness.

As we are cognizant of only a fraction of the available visual inputs at any given time, how is information selected for access to consciousness? In particular, does the personal significance of stimuli influence perceptual selection? Given that self-relevant information is prioritized during various stages of processing, here we hypothesized that self-association may privilege access to awareness under continuous flash suppression (CFS). The results supported this prediction. Compared with geometric shapes referenced to either a friend or stranger, those previously associated with self were prioritized in visual awareness. To establish the basis of this effect, the processes underlying task performance were investigated using a hierarchical drift diffusion model approach. These analyses showed that self-prioritization mapped onto both the decisional (i.e., starting value, z) and nondecisional (i.e., t₀) parameters of the diffusion model. The implications of these findings are considered. (PsycINFO Database Recor

Phasic alertness and multisensory integration contribute to visual awareness of weak visual targets in audio-visual stimulation under Continuous Flash Suppression

This work was supported by the Biotechnology and Biological Sciences Research Council(BBSRC) [grant number BB/M010996/1].Peer reviewedPublisher PD