scholarly journals Spared perilesional V1 activity underlies training-induced recovery of luminance detection sensitivity in cortically-blind patients

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Antoine Barbot ◽  
Anasuya Das ◽  
Michael D. Melnick ◽  
Matthew R. Cavanaugh ◽  
Elisha P. Merriam ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Discrimination ◽  
Receptive Fields ◽  
Visual Field Loss ◽  
Detection Sensitivity ◽  
Perceptual Training ◽  
Visual Functions ◽  
Before And After ◽  
Plastic Changes ◽  
V1 Cortex

AbstractDamage to the primary visual cortex (V1) causes homonymous visual-field loss long considered intractable. Multiple studies now show that perceptual training can restore visual functions in chronic cortically-induced blindness (CB). A popular hypothesis is that training can harness residual visual functions by recruiting intact extrageniculostriate pathways. Training may also induce plastic changes within spared regions of the damaged V1. Here, we link changes in luminance detection sensitivity with retinotopic fMRI activity before and after visual discrimination training in eleven patients with chronic, stroke-induced CB. We show that spared V1 activity representing perimetrically-blind locations prior to training predicts the amount of training-induced recovery of luminance detection sensitivity. Additionally, training results in an enlargement of population receptive fields in perilesional V1, which increases blind-field coverage and may support further recovery with subsequent training. These findings uncover fundamental changes in perilesional V1 cortex underlying training-induced restoration of conscious luminance detection sensitivity in CB.

scholarly journals Changes in perilesional V1 underlie training-induced recovery in cortically-blind patients

2020 ◽  
Author(s):  
Antoine Barbot ◽  
Anasuya Das ◽  
Michael D. Melnick ◽  
Matthew R. Cavanaugh ◽  
Elisha P. Merriam ◽  
...  
Keyword(s):  
Visual Discrimination ◽  
Receptive Fields ◽  
Visual Field Loss ◽  
Cortical Blindness ◽  
Detection Sensitivity ◽  
Perceptual Training ◽  
Before And After ◽  
Plastic Changes ◽  
V1 Cortex ◽  
Blind Patients

Damage to the primary visual cortex (V1) causes profound, homonymous visual-field loss termed cortical blindness (CB). Though long considered intractable, multiple studies now show that perceptual training can recover visual functions in chronic CB. A popular hypothesis is that training recruits intact extrageniculostriate pathways. Alternatively, training may induce plastic changes within spared regions of the damaged V1. Here, we linked changes in luminance detection sensitivity with retinotopic fMRI activity in eleven chronic CB patients, before and after extensive visual discrimination training. Our results show that the strength of spared V1 activity representing perimetrically blind-field locations before training predicts the amount of training-induced recovery of luminance detection sensitivity. Additionally, training caused an enlargement of population receptive fields in perilesional V1 cortex, which increased blind-field coverage. These findings uncover fundamental changes in perilesional V1 cortex underlying training-induced restoration of conscious luminance detection sensitivity in cortically-blind patients.

Spatially Consistent, Localized Visual Field Loss before and after Disc Hemorrhage

2009 ◽  
Vol 50 (10) ◽  
pp. 4727 ◽  
Author(s):  
Carlos Gustavo V. De Moraes ◽  
Tiago S. Prata ◽  
Craig A. Liebmann ◽  
Celso Tello ◽  
Robert Ritch ◽  
...  
Keyword(s):  
Visual Field ◽  
Visual Field Loss ◽  
Disc Hemorrhage ◽  
Before And After

scholarly journals Linking Multi-Modal MRI to Clinical Measures of Visual Field Loss After Stroke

2022 ◽  
Vol 15 ◽  
Author(s):  
Anthony Beh ◽  
Paul V. McGraw ◽  
Ben S. Webb ◽  
Denis Schluppeck
Keyword(s):  
White Matter ◽  
Visual Field ◽  
Brain Imaging ◽  
Vision Loss ◽  
Receptive Fields ◽  
Visual Field Loss ◽  
Visual Pathway ◽  
Sensitivity Threshold ◽  
Treatment Pathways ◽  
Cortical Areas

Loss of vision across large parts of the visual field is a common and devastating complication of cerebral strokes. In the clinic, this loss is quantified by measuring the sensitivity threshold across the field of vision using static perimetry. These methods rely on the ability of the patient to report the presence of lights in particular locations. While perimetry provides important information about the intactness of the visual field, the approach has some shortcomings. For example, it cannot distinguish where in the visual pathway the key processing deficit is located. In contrast, brain imaging can provide important information about anatomy, connectivity, and function of the visual pathway following stroke. In particular, functional magnetic resonance imaging (fMRI) and analysis of population receptive fields (pRF) can reveal mismatches between clinical perimetry and maps of cortical areas that still respond to visual stimuli after stroke. Here, we demonstrate how information from different brain imaging modalities—visual field maps derived from fMRI, lesion definitions from anatomical scans, and white matter tracts from diffusion weighted MRI data—provides a more complete picture of vision loss. For any given location in the visual field, the combination of anatomical and functional information can help identify whether vision loss is due to absence of gray matter tissue or likely due to white matter disconnection from other cortical areas. We present a combined imaging acquisition and visual stimulus protocol, together with a description of the analysis methodology, and apply it to datasets from four stroke survivors with homonymous field loss (two with hemianopia, two with quadrantanopia). For researchers trying to understand recovery of vision after stroke and clinicians seeking to stratify patients into different treatment pathways, this approach combines multiple, convergent sources of data to characterize the extent of the stroke damage. We show that such an approach gives a more comprehensive measure of residual visual capacity—in two particular respects: which locations in the visual field should be targeted and what kind of visual attributes are most suited for rehabilitation.

scholarly journals Organization of Area hV5/MT+ in Subjects with Homonymous Visual Field Defects

2018 ◽  
Author(s):  
Amalia Papanikolaou ◽  
Georgios A. Keliris ◽  
T. Dorina Papageorgiou ◽  
Ulrich Schiefer ◽  
Nikos K. Logothetis ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Visual Perception ◽  
Activity Patterns ◽  
Receptive Fields ◽  
Visual Field Loss ◽  
Visual Sensitivity ◽  
Visual Field Defects ◽  
Temporal Area ◽  
Residual Capacity

AbstractDamage to the primary visual cortex (V1) leads to a visual field loss (scotoma) in the retinotopically corresponding part of the visual field. Nonetheless, a small amount of residual visual sensitivity persists within the blind field. This residual capacity has been linked to activity observed in the middle temporal area complex (V5/MT+). However, it remains unknown whether the organization of hV5/MT+ changes following V1 lesions. We studied the organization of area hV5/MT+ of five patients with dense homonymous defects in a quadrant of the visual field as a result of partial V1+ or optic radiation lesions. To do so, we developed a new method, which models the boundaries of population receptive fields directly from the BOLD signal of each voxel in the visual cortex. We found responses in hV5/MT+ arising inside the scotoma for all patients and identified two possible sources of activation: 1) responses might originate from partially lesioned parts of area V1 corresponding to the scotoma, and 2) responses can also originate independent of area V1 input suggesting the existence of functional V1-bypassing pathways. Apparently, visually driven activity observed in hV5/MT+ is not sufficient to mediate conscious vision. More surprisingly, visually driven activity in corresponding regions of V1 and early extrastriate areas including hV5/MT+ did not guarantee visual perception in the group of patients with post-geniculate lesions that we examined. This suggests that the fine coordination of visual activity patterns across visual areas may be an important determinant of whether visual perception persists following visual cortical lesions.

Rates of visual field loss before and after trabeculectomy

2013 ◽  
Vol 92 (2) ◽  
pp. 116-120 ◽  
Author(s):  
Valérie Bertrand ◽  
Steffen Fieuws ◽  
Ingeborg Stalmans ◽  
Thierry Zeyen
Keyword(s):  
Visual Field ◽  
Visual Field Loss ◽  
Before And After

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

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Arash Sahraie ◽  
Nicola Smania ◽  
Josef Zihl
Keyword(s):  
Visual Search ◽  
Visual Field ◽  
Eye Movement ◽  
Group Performance ◽  
Visual Field Loss ◽  
Control Group ◽  
Movement Training ◽  
Visual Field Deficits ◽  
Before And After ◽  
Healthy Control

Visual field deficits are common in patients with damaged retinogeniculostriate pathways. The patient’s eye movements are often affected leading to inefficient visual search. Systematic eye movement training also called compensatory therapy is needed to allow patients to develop effective coping strategies. There is a lack of evidence-based, clinical gold-standard registered medical device accessible to patients at home or in clinical settings and NeuroEyeCoach (NEC) is developed to address this need. In three experiments, we report on performance of patients on NEC compared to the data obtained previously on the earlier versions of the search task (n=32); we assessed whether the self-administered computerised tasks can be used to monitor the progress (n=24) and compared the findings in a subgroup of patients to a healthy control group. Performance on cancellation tasks, simple visual search, and self-reported responses on activities of daily living was compared, before and after training. Patients performed similarly well on NEC as on previous versions of the therapy; the inbuilt functionality for pre- and postevaluation functions was sensitive to allowing assessment of improvements; and improvements in patients were significantly greater than those in a group of healthy adults. In conclusion, NeuroEyeCoach can be used as an effective rehabilitation tool to develop compensatory strategies in patients with visual field deficits after brain injury.

scholarly journals Highly accurate retinotopic maps of the physiological blind spot in human visual cortex

2021 ◽  
Author(s):  
Poutasi W. B. Urale ◽  
Alexander Michael Puckett ◽  
Ashley York ◽  
Derek Arnold ◽  
D. Sam Schwarzkopf
Keyword(s):  
Visual Field ◽  
Receptive Fields ◽  
Visual Field Loss ◽  
Blind Spot ◽  
Neural Circuitry ◽  
Extrastriate Cortex ◽  
Retinotopic Maps ◽  
Naturally Occurring ◽  
Perceptual Completion ◽  
Retinotopic Organization

The physiological blind spot is a naturally occurring scotoma corresponding with the optic disc in the retina of each eye. Even during monocular viewing, observers are usually oblivious to the scotoma, in part because the visual system extrapolates information from the surrounding area. Unfortunately, studying this visual field region with neuroimaging has proven difficult, as it occupies only a small part of retinotopic cortex. Here we used functional magnetic resonance imaging and a novel data-driven method for mapping the retinotopic organization in and around the blind spot representation in V1. Our approach allowed for highly accurate reconstructions of the extent of an observer's blind spot, and out-performed conventional model-based analyses. This method opens exciting opportunities to study the plasticity of receptive fields after visual field loss, and our data add to evidence suggesting that the neural circuitry responsible for impressions of perceptual completion across the physiological blind spot most likely involves regions of extrastriate cortex - beyond V1.

scholarly journals Search training for people with visual field loss after stroke: A cohort study

2017 ◽  
Vol 81 (5) ◽  
pp. 255-265
Author(s):  
Ailie J Turton ◽  
Jayne Angilley ◽  
Verity Longley ◽  
Philip Clatworthy ◽  
Iain D Gilchrist
Keyword(s):  
Visual Field ◽  
Visual Function ◽  
Visual Field Loss ◽  
Gaze Tracking ◽  
Patient Reports ◽  
Patient Reported ◽  
Before And After ◽  
Visual Function Questionnaire ◽  
Improved Performance ◽  
Search Training

Introduction People with visual field loss after stroke often experience difficulties in everyday activities. The purpose of this study was to assess the acceptability of search training as used within occupational therapy and the feasibility of possible measures for use in a future trial. Method Nine participants took part in a goal oriented intervention that was delivered three times a week for 3 weeks. Patient reports of acceptability and outcomes using the Visual Function Questionnaire-25 were collected. Participants’ room-search behaviour before and after the intervention was recorded using a head-worn camera. Results Eight participants completed nine treatment visits. All participants reported improved awareness and attention to the blind side during activities following the intervention. Seven participants’ change scores on the Visual Function Questionnaire-25 exceeded six points. Patterns of head-direction behaviour and overall room-search times were variable across patients; markedly, improved performance was only evident in the most severely affected participant. Conclusion The intervention was acceptable. The Visual Function Questionnaire-25 is a feasible measure for assessing patient-reported outcomes. While the room search was informative about individuals’ behaviour, more sophisticated methods of gaze tracking would allow search processes to be determined in real-world activities that are relevant to patients’ goals.

Modified endoscopic optic nerve decompression in idiopathic intracranial hypertension

2003 ◽  
Vol 117 (6) ◽  
pp. 501-502 ◽  
Author(s):  
Ashok K. Gupta ◽  
M. G. Rajini Ganth ◽  
Amod Gupta
Keyword(s):  
Optic Nerve ◽  
Visual Field ◽  
Intracranial Hypertension ◽  
Idiopathic Intracranial Hypertension ◽  
Visual Field Loss ◽  
Visual Functions ◽  
Nerve Decompression ◽  
Endoscopic Control ◽  
Optic Nerve Decompression

A case of idiopathic intracranial hypertension (IIH) with visual field loss was decompressed in the intracanalicular segment of the optic nerve transnasally under endoscopic control. Visual functions improved after surgery.

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