Cortical Thickness Related to Compensatory Viewing Strategies in Patients With Macular Degeneration

Retinal diseases like age-related macular degeneration (AMD) or hereditary juvenile macular dystrophies (JMD) lead to a loss of central vision. Many patients compensate for this loss with a pseudo fovea in the intact peripheral retina, the so-called “preferred retinal locus” (PRL). How extensive eccentric viewing associated with central vision loss (CVL) affects brain structures responsible for visual perception and visually guided eye movements remains unknown. CVL results in a reduction of cortical gray matter in the “lesion projection zone” (LPZ) in early visual cortex, but the thickness of primary visual cortex appears to be largely preserved for eccentric-field representations. Here we explore how eccentric viewing strategies are related to cortical thickness (CT) measures in early visual cortex and in brain areas involved in the control of eye movements (frontal eye fields, FEF, supplementary eye fields, SEF, and premotor eye fields, PEF). We determined the projection zones (regions of interest, ROIs) of the PRL and of an equally peripheral area in the opposite hemifield (OppPRL) in early visual cortex (V1 and V2) in 32 patients with MD and 32 age-matched controls (19–84 years) by functional magnetic resonance imaging. Subsequently, we calculated the CT in these ROIs and compared it between PRL and OppPRL as well as between groups. Additionally, we examined the CT of FEF, SEF, and PEF and correlated it with behavioral measures like reading speed and eccentric fixation stability at the PRL. We found a significant difference between PRL and OppPRL projection zones in V1 with increased CT at the PRL, that was more pronounced in the patients, but also visible in the controls. Although the mean CT of the eye fields did not differ significantly between patients and controls, we found a trend to a positive correlation between CT in the right FEF and SEF and fixation stability in the whole patient group and between CT in the right PEF and reading speed in the JMD subgroup. The results indicate a possible association between the compensatory strategies used by patients with CVL and structural brain properties in early visual cortex and cortical eye fields.

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Does Inverting Text Improve Reading Performance in Homonymous Hemianopes?

Perception ◽

10.1068/v970039 ◽

1997 ◽

Vol 26 (1_suppl) ◽

pp. 77-77

Author(s):

M R Baker ◽

J Henderson ◽

A Hill

Keyword(s):

Eye Movements ◽

Low Vision ◽

Reading Speed ◽

Leading Edge ◽

Visual Field Loss ◽

Reading Performance ◽

Sensory Level ◽

Eye Tracker ◽

Cognitive Component ◽

The Right

Anecdotal information from rehabilitation practice of reading performance and low-vision practice suggests that where right homonymous parafoveal field loss impairs reading at the visual-sensory level, an improvement in reading speed can be achieved by inverting the text. This is because whilst left-field loss is considered to impair return eye movements to the beginning of a line, right-field loss is considered to reduce the spatial size of the perceptual window and increase its temporal extent by prolonging fixations times, reducing the amplitudes of saccades to the right, and introducing frequent regressive saccades. Inverting the text was thought to reverse these effects as the leading edge of the perceptual window is ‘returned’ to the sighted field so that in-line saccades can be visually guided. Here we report that this does not appear to be the case. In our study we measured the eye movements of patients with right homonymous hemianopia and others with peripheral loss due to retinitis pigmentosa as well as normal controls using an infrared video eye-tracker. All groups display a similar proportional prolongation of fixations times, reduction of saccadic amplitude, and proportion of regressive saccades when asked to read inverted text, which suggests a cognitive component of impairment independent of visual field loss in right homonymous hemianopes.

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Biofeedback fixation training method for improving eccentric vision in patients with loss of foveal function secondary to different maculopathies

International Ophthalmology ◽

10.1007/s10792-019-01180-y ◽

2019 ◽

Vol 40 (2) ◽

pp. 305-312 ◽

Cited By ~ 5

Author(s):

Marco U. Morales ◽

Saker Saker ◽

Craig Wilde ◽

Martin Rubinstein ◽

Paolo Limoli ◽

...

Keyword(s):

Vision Loss ◽

Reading Speed ◽

Light Sensitivity ◽

Central Vision ◽

Functional Characteristics ◽

Eccentric Fixation ◽

Central Vision Loss ◽

Fixation Stability ◽

Group A ◽

Group B

Abstract Purpose Fixation stability (FS) of the preferred retinal locus (PRL) may be improved by biofeedback fixation training (BFT) with microperimetry. Such training can be done on the patient’s PRL or in different retinal loci with better functional characteristics. We studied both options and compared the outcomes. Methods Sixty-seven consecutive patients with bilateral central vision loss, poor FS and visual acuity (VA) lower than 0.3 LogMAR were recruited for BFT with microperimeter. Patients were assigned into 2 groups. In group A, BFT was performed on the patient’s spontaneous PRL. In group B, PRL was located between 2 adjacent loci with the highest light sensitivity and the lowest distance from the fovea. Two sets of 12 weekly BFT sessions were performed. Primary outcomes were: FS, VA and reading speed. Results Outcomes were statistically significantly better in group B. Mean percentage of FS at therapy end improved from 32 to 35% for group A and from 40 to 55% in group B. Mean VA improved from 1 to 0.86 in group A and from 1 to 0.84 in group B. Reading speed (wpm) improved from 56 to 58 in group A and from 63 to 89 in group B. Conclusions This study describes a reliable methodology of improving eccentric fixation stability using BFT in microperimetry, when the fixation training locus is individualized as the retinal area with best functional characteristics. Further studies are needed to validate its value in a larger scale of patients, at different stages of the disease, and its persistence over time.

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Vision Rehabilitation in Patients with Age-related Macular Degeneration

Rehabilitation Process and Outcome ◽

10.4137/rpo.s12364 ◽

2014 ◽

Vol 3 ◽

pp. RPO.S12364 ◽

Cited By ~ 1

Author(s):

Filippo M. Amore ◽

Stefania Fortini ◽

Valeria Silvestri ◽

Marco Sulfaro ◽

Alessia Pacifici ◽

...

Keyword(s):

Visual Acuity ◽

Macular Degeneration ◽

Visual Stimulation ◽

Low Vision ◽

Reading Speed ◽

Age Related Macular Degeneration ◽

International Agency ◽

Visual Rehabilitation ◽

Age Related ◽

Fixation Stability

Background The aim of this study was to investigate the rehabilitative process and visual rehabilitation outcomes in patients with central vision loss due to age-related macular degeneration (AMD). Methods Ninety-five subjects with AMD selected from the attendees of the National Centre of Services and Research for the Prevention of Blindness and Rehabilitation of Low Vision Patients—International Agency for Prevention of Blindness—IAPB Italia Onlus, were evaluated for this retrospective study. Low vision examination included psychological counseling, best corrected visual acuity (BCVA), near visual acuity, Pelli-Robson contrast sensitivity, and fixation stability analysis. Once the clinical assessment was completed, patients attended a low-vision rehabilitative pathway based on visual stimulation, devices training and, if needed, psychological support. Required magnification and reading speed were also evaluated. Results For the whole sample, the mean BCVA of the better eye was 0.7 (±0.2) LogMAR and of the worse eye was 1 (±0.2) LogMAR. Restoring reading ability was the most important focus for the patients examined as it was requested by 85% of the whole sample. Mean power of optical magnifying aids for near activities was 10.6 (±9.1) positive spherical diopters. Mean reading speed for the whole sample was 33.1 (±18.2) words per minute (wpm) before visual rehabilitation sessions and increased to 55.2 (±33.1) wpm after visual rehabilitation path. To cope with distance difficulties, 78 distance refractive correction, 10 Galilean telescopes, and 7 Keplerian telescopes were prescribed. For intermediate distance activities, 22 compensation lenses and 10 Galilean telescopes were suggested. Moreover, PC magnifier softwares were prescribed to nine patients. Sixty-five polarized medical filters were prescribed to reduce glare of sunlight. Because of unstable fixation in their better eye (32.3% (±19.7) within 2° circle and 54.8% (±22.9) within 4° circle) and visual acuity < 1.2 LogMAR in the fellow eye, 38 subjects, before starting the devices training sessions, attended a bio-feedback rehabilitation session with flickering pattern stimulus. In these subjects, fixation stability increased significantly to 75.6 (±14.9) within 2° and 89.4 (±19.5) within 4° ( P < 0.05), respectively. Conclusions Attending a customized low-vision intervention based on a multidisciplinary approach seems to be effective for improving visual functions in AMD. Both optical/electronic magnifiers and specific visual stimulation program can enhance visual performances.

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Visual working memory representations in visual and parietal cortex do not remap after eye movements

10.1101/747329 ◽

2019 ◽

Author(s):

Tao He ◽

Matthias Ekman ◽

Annelinde R.E. Vandenbroucke ◽

Floris P. de Lange

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Eye Movements ◽

Visual Field ◽

Visual System ◽

Visual Working Memory ◽

Parietal Cortex ◽

List Type ◽

Early Visual Cortex

ABSTRACTIt has been suggested that our visual system does not only process stimuli that are directly available to our eyes, but also has a role in maintaining information in VWM over a period of seconds. It remains unclear however what happens to VWM representations in the visual system when we make saccades. Here, we tested the hypothesis that VWM representations are remapped within the visual system after making saccades. We directly compared the content of VWM for saccade and no-saccade conditions using MVPA of delay-related activity measured with fMRI. We found that when participants did not make a saccade, VWM representations were robustly present in contralateral early visual cortex. When making a saccade, VWM representations degraded in contralateral V1-V3 after the saccade shifted the location of the remembered grating to the opposite visual field. However, contrary to our hypothesis we found no evidence for the representations of the remembered grating at the saccadic target location in the opposite visual field, suggesting that there is no evidence for remapping of VWM in early visual cortex. Interestingly, IPS showed persistent VWM representations in both the saccade and no-saccade condition. Together, our results indicate that VWM representations in early visual cortex are not remapped across eye movements, potentially limiting the role of early visual cortex in VWM storage.HighlightsVisual working memory (VWM) representations do not remap after making saccadesEye movement degrade VWM representations in early visual cortex, limiting the role of early visual cortex in VWM storageParietal cortex shows persistent VWM representations across saccades

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The influence of objecthood on the representation of natural images in the visual cortex

10.1101/2021.09.21.461209 ◽

2021 ◽

Author(s):

Paolo Papale ◽

Wietske Zuiderbaan ◽

Rob R.M. Teeuwen ◽

Amparo Gilhuis ◽

Matthew W. Self ◽

...

Keyword(s):

Visual Cortex ◽

Eye Movements ◽

Neuronal Activity ◽

Cortical Neurons ◽

Neuronal Response ◽

Late Phase ◽

Object Perception ◽

Natural Images ◽

Early Visual Cortex ◽

Visual Cortical

Neurons in early visual cortex are not only sensitive to the image elements in their receptive field but also to the context determining whether the elements are part of an object or background. We here assessed the effect of objecthood in natural images on neuronal activity in early visual cortex, with fMRI in humans and electrophysiology in monkeys. We report that boundaries and interiors of objects elicit more activity than the background. Boundary effects occur remarkably early, implying that visual cortical neurons are tuned to features characterizing object boundaries in natural images. When a new image is presented the influence of the object interiors on neuronal activity occurs during a late phase of neuronal response and earlier when eye movements shift the image representation, implying that object representations are remapped across eye-movements. Our results reveal how object perception shapes the representation of natural images in early visual cortex.

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The Experience of a Randomized Clinical Trial of Closed-Circuit Television versus Eccentric Viewing Training for People with Age-Related Macular Degeneration

Journal of Visual Impairment & Blindness ◽

10.1177/0145482x1711100405 ◽

2017 ◽

Vol 111 (4) ◽

pp. 354-368 ◽

Cited By ~ 2

Author(s):

Susan J. Leat ◽

Francie Fengqin Si ◽

Deborah Gold ◽

Dawn Pickering ◽

Keith Gordon ◽

...

Keyword(s):

Visual Acuity ◽

Macular Degeneration ◽

Vision Loss ◽

Low Vision ◽

Reading Speed ◽

Optical Devices ◽

Reading Performance ◽

Age Related Macular Degeneration ◽

Eccentric Viewing ◽

Age Related

Introduction In addition to optical devices, closed-circuit televisions (CCTVs) and eccentric viewing training are both recognized interventions to improve reading performance in individuals with vision loss secondary to age-related macular degeneration. Both are relatively expensive, however, either in the cost of the device or in the amount of time personnel need to provide training. In this randomized trial, we compared the effectiveness of these two interventions. Methods Participants with age-related macular degeneration and visual acuity between 6/48 (20/160) and 6/120 (20/400) first received basic low vision care, including optical devices. At the subsequent baseline visit, they undertook a battery of measures including logMAR visual acuity; reading speed and accuracy for text in 1.3M and 1M fonts; reading information on medicine bottles, utility bills, and food packages; the NEI-VFQ; the Geriatric Depression Scale; and a reading inventory questionnaire. They were then randomized to either obtaining a CCTV for home use or eccentric viewing training over the following six weeks. Results Recruitment was more difficult than expected for this population. Of 145 patients referred, 29 met the inclusion-exclusion criteria, 14 were willing to enroll, and 10 completed the trial. For the primary outcome (reading speed for 1.3M print), there was a significant improvement between baseline and outcome for the CCTV group (p = 0.005), but not for the eccentric viewing training group (p = 0.28), and the CCTV group showed significantly greater change (p = 0.04). There was a nonsignificant improvement in reading speed for 1M text and a decrease in the amount of time taken to read utility bill information in the CCTV group. There was a significant improvement in near visual acuity with current glasses with eccentric viewing training. The other measures did not reach statistical significance. Discussion Randomized clinical trials for low vision rehabilitation, particularly in the elderly population with vision loss, are challenging, but such trials are important for the allocation of resources. This trial showed early indications of more impact on reading performance from CCTV than eccentric viewing training.

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Gaze direction influences grasping actions towards unseen, haptically explored, objects

Scientific Reports ◽

10.1038/s41598-020-72554-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Martina Pirruccio ◽

Simona Monaco ◽

Chiara Della Libera ◽

Luigi Cattaneo

Keyword(s):

Visual Cortex ◽

Visual Information ◽

Oculomotor System ◽

Frame Of Reference ◽

Gaze Direction ◽

Eye Position ◽

Object Representations ◽

Haptic Information ◽

Early Visual Cortex ◽

The Right

Abstract Haptic exploration produces mental object representations that can be memorized for subsequent object-directed behaviour. Storage of haptically-acquired object images (HOIs), engages, besides canonical somatosensory areas, the early visual cortex (EVC). Clear evidence for a causal contribution of EVC to HOI representation is still lacking. The use of visual information by the grasping system undergoes necessarily a frame of reference shift by integrating eye-position. We hypothesize that if the motor system uses HOIs stored in a retinotopic coding in the visual cortex, then its use is likely to depend at least in part on eye position. We measured the kinematics of 4 fingers in the right hand of 15 healthy participants during the task of grasping different unseen objects behind an opaque panel, that had been previously explored haptically. The participants never saw the object and operated exclusively based on haptic information. The position of the object was fixed, in front of the participant, but the subject’s gaze varied from trial to trial between 3 possible positions, towards the unseen object or away from it, on either side. Results showed that the middle and little fingers’ kinematics during reaching for the unseen object changed significantly according to gaze position. In a control experiment we showed that intransitive hand movements were not modulated by gaze direction. Manipulating eye-position produces small but significant configuration errors, (behavioural errors due to shifts in frame of reference) possibly related to an eye-centered frame of reference, despite the absence of visual information, indicating sharing of resources between the haptic and the visual/oculomotor system to delayed haptic grasping.

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Differences in Cortical Thickness Reflect Differences in Plasticity of Visual Cortex Between Juvenile and Age-related Macular Degeneration

Journal of Vision ◽

10.1167/17.10.645 ◽

2017 ◽

Vol 17 (10) ◽

pp. 645

Author(s):

Matthew Defenderfer ◽

Mark Greenlee ◽

Antony Morland ◽

Frans Cornelissen ◽

Kristina Visscher

Keyword(s):

Visual Cortex ◽

Macular Degeneration ◽

Cortical Thickness ◽

Age Related Macular Degeneration ◽

Age Related

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Evidence for confounding eye movements under attempted fixation and active viewing in cognitive neuroscience

Scientific Reports ◽

10.1038/s41598-019-54018-z ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 4

Author(s):

Jordy Thielen ◽

Sander E. Bosch ◽

Tessa M. van Leeuwen ◽

Marcel A. J. van Gerven ◽

Rob van Lier

Keyword(s):

Visual Cortex ◽

Eye Movements ◽

Cognitive Neuroscience ◽

Neural Decoding ◽

Fixational Eye Movements ◽

Passive Viewing ◽

Early Visual Cortex

AbstractEye movements can have serious confounding effects in cognitive neuroscience experiments. Therefore, participants are commonly asked to fixate. Regardless, participants will make so-called fixational eye movements under attempted fixation, which are thought to be necessary to prevent perceptual fading. Neural changes related to these eye movements could potentially explain previously reported neural decoding and neuroimaging results under attempted fixation. In previous work, under attempted fixation and passive viewing, we found no evidence for systematic eye movements. Here, however, we show that participants’ eye movements are systematic under attempted fixation when active viewing is demanded by the task. Since eye movements directly affect early visual cortex activity, commonly used for neural decoding, our findings imply alternative explanations for previously reported results in neural decoding.

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Reduced Fading of Visual Afterimages after Transcranial Magnetic Stimulation over Early Visual Cortex

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01415 ◽

2019 ◽

Vol 31 (9) ◽

pp. 1368-1379

Author(s):

Tahnée Engelen ◽

Rosanne L. Rademaker ◽

Alexander T. Sack

Keyword(s):

Visual Cortex ◽

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Brain Regions ◽

Visual Signals ◽

Visual Inputs ◽

Before And After ◽

Integration Sites ◽

Early Visual Cortex ◽

The Right

In the complete absence of small transients in visual inputs (e.g., by experimentally stabilizing an image on the retina or in everyday life during intent staring), information perceived by the eyes will fade from the perceptual experience. Although the mechanisms of visual fading remain poorly understood, one possibility is that higher level brain regions actively suppress the stable visual signals via targeted feedback onto early visual cortex (EVC). Here, we used positive afterimages and multisensory conflict to induce gestalt-like fading of participants' own hands. In two separate experiments, participants rated the perceived quality of their hands both before and after transcranial magnetic stimulation (TMS) was applied over EVC. In a first experiment, triple-pulse TMS was able to make a faded hand appear less faded after the pulses were applied, compared with placebo pulses. A second experiment demonstrated that this was because triple-pulse TMS slowed down fading of the removed hand that otherwise occurs naturally over time. Interestingly, TMS similarly affected the left and right hands, despite being applied only over the right EVC. Together, our results suggest that TMS over EVC attenuates the effects of visual fading in positive afterimages, and it might do so by crossing transcollosal connections or via multimodal integration sites in which both hands are represented.

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