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Carrasco M, Spering M. Perception-action Dissociations as a Window into Consciousness. J Cogn Neurosci 2024; 36:1557-1566. [PMID: 38865201 DOI: 10.1162/jocn_a_02122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Understanding the neural correlates of unconscious perception stands as a primary goal of experimental research in cognitive psychology and neuroscience. In this Perspectives paper, we explain why experimental protocols probing qualitative dissociations between perception and action provide valuable insights into conscious and unconscious processing, along with their corresponding neural correlates. We present research that utilizes human eye movements as a sensitive indicator of unconscious visual processing. Given the increasing reliance on oculomotor and pupillary responses in consciousness research, these dissociations also provide a cautionary tale about inferring conscious perception solely based on no-report protocols.
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Dogra N, Redmond BV, Lilley S, Johnson BA, Lam BL, Tamhankar M, Feldon SE, Fahrenthold B, Yang J, Huxlin KR, Cavanaugh MR. Vision-related quality of life after unilateral occipital stroke. Brain Behav 2024; 14:e3582. [PMID: 38956813 PMCID: PMC11219293 DOI: 10.1002/brb3.3582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 04/22/2024] [Accepted: 05/17/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND/OBJECTIVES Stroke damage to the primary visual cortex induces large, homonymous visual field defects that impair daily living. Here, we asked if vision-related quality of life (VR-QoL) is impacted by time since stroke. SUBJECTS/METHODS We conducted a retrospective meta-analysis of 95 occipital stroke patients (female/male = 26/69, 27-78 years old, 0.5-373.5 months poststroke) in whom VR-QoL was estimated using the National Eye Institute Visual Functioning Questionnaire (NEI-VFQ) and its 10-item neuro-ophthalmic supplement (Neuro10). Visual deficit severity was represented by the perimetric mean deviation (PMD) calculated from 24-2 Humphrey visual fields. Data were compared with published cohorts of visually intact controls. The relationship between VR-QoL and time poststroke was assessed across participants, adjusting for deficit severity and age with a multiple linear regression analysis. RESULTS Occipital stroke patients had significantly lower NEI-VFQ and Neuro10 composite scores than controls. All subscale scores describing specific aspects of visual ability and functioning were impaired except for ocular pain and general health, which did not differ significantly from controls. Surprisingly, visual deficit severity was not correlated with either composite score, both of which increased with time poststroke, even when adjusting for PMD and age. CONCLUSIONS VR-QoL appears to improve with time postoccipital stroke, irrespective of visual deficit size or patient age at insult. This may reflect the natural development of compensatory strategies and lifestyle adjustments. Thus, future studies examining the impact of rehabilitation on daily living in this patient population should consider the possibility that their VR-QoL may change gradually over time, even without therapeutic intervention.
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Affiliation(s)
- Neil Dogra
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Bryan V. Redmond
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Selena Lilley
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Brent A. Johnson
- Department of Biostatistics and Computational BiologyUniversity of RochesterRochesterNew YorkUSA
| | - Byron L. Lam
- Bascom Palmer Eye InstituteUniversity of MiamiMiamiFloridaUSA
| | - Madhura Tamhankar
- Scheie Eye InstituteUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Steven E. Feldon
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Berkeley Fahrenthold
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Jingyi Yang
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Krystel R. Huxlin
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
| | - Matthew R. Cavanaugh
- Department of Ophthalmology, Flaum Eye Institute and Center for Visual ScienceUniversity of RochesterRochesterNew YorkUSA
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Zueva MV, Neroeva NV, Zhuravleva AN, Bogolepova AN, Kotelin VV, Fadeev DV, Tsapenko IV. Fractal Phototherapy in Maximizing Retina and Brain Plasticity. ADVANCES IN NEUROBIOLOGY 2024; 36:585-637. [PMID: 38468055 DOI: 10.1007/978-3-031-47606-8_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.
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Affiliation(s)
- Marina V Zueva
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Natalia V Neroeva
- Department of Pathology of the Retina and Optic Nerve, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anastasia N Zhuravleva
- Department of Glaucoma, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Anna N Bogolepova
- Department of neurology, neurosurgery and medical genetics, Pirogov Russian National Research Medical University, Moscow, Russia
| | - Vladislav V Kotelin
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Denis V Fadeev
- Scientific Experimental Center Department, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Irina V Tsapenko
- Department of Clinical Physiology of Vision, Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
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Urale PWB, Zhu L, Gough R, Arnold D, Schwarzkopf DS. Extrastriate activity reflects the absence of local retinal input. Conscious Cogn 2023; 114:103566. [PMID: 37639775 DOI: 10.1016/j.concog.2023.103566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/01/2023] [Accepted: 08/14/2023] [Indexed: 08/31/2023]
Abstract
The physiological blind spot corresponds to the optic disc where the retina contains no light-detecting photoreceptor cells. Our perception seemingly fills in this gap in input. Here we suggest that rather than an active process, such perceptual filling-in could instead be a consequence of the integration of visual inputs at higher stages of processing discounting the local absence of retinal input. Using functional brain imaging, we resolved the retinotopic representation of the physiological blind spot in early human visual cortex and measured responses while participants perceived filling-in. Responses in early visual areas simply reflected the absence of visual input. In contrast, higher extrastriate regions responded more to stimuli in the eye containing the blind spot than the fellow eye. However, this signature was independent of filling-in. We argue that these findings agree with philosophical accounts that posit that the concept of filling-in of absent retinal input is unnecessary.
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Affiliation(s)
- Poutasi W B Urale
- School of Optometry & Vision Science, University of Auckland, New Zealand
| | - Lydia Zhu
- School of Optometry & Vision Science, University of Auckland, New Zealand
| | - Roberta Gough
- School of Optometry & Vision Science, University of Auckland, New Zealand
| | - Derek Arnold
- School of Psychology, University of Queensland, Brisbane, Australia; Queensland Brain Institute, University of Queensland, Brisbane, Australia
| | - Dietrich Samuel Schwarzkopf
- School of Optometry & Vision Science, University of Auckland, New Zealand; Experimental Psychology, University College London, United Kingdom.
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Wang J, Zou L, Jiang X, Wang D, Mao L, Yang X. Visual stimulation rehabilitation for cortical blindness after vertebral artery interventional surgery: A case report and literature review. Int J Surg Case Rep 2023; 110:108753. [PMID: 37651808 PMCID: PMC10509878 DOI: 10.1016/j.ijscr.2023.108753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023] Open
Abstract
INTRODUCTION AND IMPORTANCE Cortical blindness (CB) after vertebral artery interventional surgery is not a frequently reported complication. In this study, the efficacy of visual stimulation rehabilitation consisting of visual recovery training and repetitive transcranial magnetic stimulation (rTMS) for cortical blindness was investigated by clinical evaluation, ophthalmologic examination, and electroencephalography (EEG). CASE PRESENTATION This study reports on a 55-year-old male who showed partial bilateral posterior cerebral artery cortical branch occlusion after timely embolectomy due to thrombus dislodgement during right vertebral artery opening, stenting resulting in basilar artery tip occlusion. The lesions were mainly located in the right cerebellar hemisphere and bilateral occipital lobes, and the patient suffered from bilateral loss of vision, with only light perception preserved. The patient began to receive visual recovery training and 15 sessions of right occipital high-frequency transcranial magnetic stimulation 5 days after the onset. CLINICAL DISCUSSION After treatment, the patient's capacity to identify things improved, allowing him to watch television, as did the precision and fluency of random hand movements, walking, and self-care. CONCLUSION Visual stimulation rehabilitation composed of visual recovery training and rTMS is a promising therapy option for cortical blindness, and our case report provides clinical experience with vision recovery for patients with cortical blindness.
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Affiliation(s)
- Juehan Wang
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Liliang Zou
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaorui Jiang
- Department of Rehabilitation Medicine, The First People's Hospital of Yuhang District, Hangzhou, China
| | - Daming Wang
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Lin Mao
- Department of Rehabilitation Medicine, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
| | - Xiaofeng Yang
- Emergency and Trauma Center, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
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Leitner MC, Ladek AM, Hutzler F, Reitsamer H, Hawelka S. Placebo effect after visual restitution training: no eye-tracking controlled perimetric improvement after visual border stimulation in late subacute and chronic visual field defects after stroke. Front Neurol 2023; 14:1114718. [PMID: 37456634 PMCID: PMC10339290 DOI: 10.3389/fneur.2023.1114718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 06/13/2023] [Indexed: 07/18/2023] Open
Abstract
Introduction A significant number of Restitution Training (RT) paradigms claim to ameliorate visual field loss after stroke by re-activating neuronal connections in the residual visual cortex due to repeated bright light-stimulation at the border of the blind and intact fields. However, the effectiveness of RT has been considered controversial both in science and clinical practice for years. The main points of the controversy are (1) the reliability of perimetric results which may be affected by compensatory eye movements and (2) heterogeneous samples consisting of patients with visual field defects and/or visuospatial neglect. Methods By means of our newly developed and validated Virtual Reality goggles Salzburg Visual Field Trainer (SVFT) 16 stroke patients performed RT on a regular basis for 5 months. By means of our newly developed and validated Eye Tracking Based Visual Field Analysis (EFA), we conducted a first-time full eye-movement-controlled perimetric pre-post intervention study. Additionally, patients subjectively rated the size of their intact visual field. Results Analysis showed that patients' mean self-assessment of their subjective visual field size indicated statistically significant improvement while, in contrast, objective eye tracking controlled perimetric results revealed no statistically significant effect. Discussion Bright-light detection RT at the blind-field border solely induced a placebo effect and did not lead to training-induced neuroplasticity in the visual cortex of the type needed to ameliorate the visual field size of stroke patients.
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Affiliation(s)
- Michael Christian Leitner
- Salzburg University of Applied Sciences, Salzburg, Austria
- Centre for Cognitive Neuroscience (CCNS), University of Salzburg, Salzburg, Austria
- Department of Psychology, University of Salzburg, Salzburg, Austria
| | - Anja-Maria Ladek
- Research Program for Experimental Ophthalmology and Glaucoma Research, Department of Ophthalmology and Optometry, University Hospital of the Paracelsus Medical University Salzburg, Salzburg, Austria
- Department of Ophthalmology and Optometry, SALK, University Hospital of the Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Florian Hutzler
- Centre for Cognitive Neuroscience (CCNS), University of Salzburg, Salzburg, Austria
- Department of Psychology, University of Salzburg, Salzburg, Austria
| | - Herbert Reitsamer
- Research Program for Experimental Ophthalmology and Glaucoma Research, Department of Ophthalmology and Optometry, University Hospital of the Paracelsus Medical University Salzburg, Salzburg, Austria
- Department of Ophthalmology and Optometry, SALK, University Hospital of the Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Stefan Hawelka
- Centre for Cognitive Neuroscience (CCNS), University of Salzburg, Salzburg, Austria
- Department of Psychology, University of Salzburg, Salzburg, Austria
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Rowland BA, Bushnell CD, Duncan PW, Stein BE. Ameliorating Hemianopia with Multisensory Training. J Neurosci 2023; 43:1018-1026. [PMID: 36604169 PMCID: PMC9908311 DOI: 10.1523/jneurosci.0962-22.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 01/06/2023] Open
Abstract
Hemianopia (unilateral blindness), a common consequence of stroke and trauma to visual cortex, is a debilitating disorder for which there are few treatments. Research in an animal model has suggested that visual-auditory stimulation therapy, which exploits the multisensory architecture of the brain, may be effective in restoring visual sensitivity in hemianopia. It was tested in two male human patients who were hemianopic for at least 8 months following a stroke. The patients were repeatedly exposed to congruent visual-auditory stimuli within their blinded hemifield during 2 h sessions over several weeks. The results were dramatic. Both recovered the ability to detect and describe visual stimuli throughout their formerly blind field within a few weeks. They could also localize these stimuli, identify some of their features, and perceive multiple visual stimuli simultaneously in both fields. These results indicate that the multisensory therapy is a rapid and effective method for restoring visual function in hemianopia.SIGNIFICANCE STATEMENT Hemianopia (blindness on one side of space) is widely considered to be a permanent disorder. Here, we show that a simple multisensory training paradigm can ameliorate this disorder in human patients.
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Affiliation(s)
| | - Cheryl D Bushnell
- Neurology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
| | - Pamela W Duncan
- Neurology, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
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Kim Y, Im S, Oh J, Jung Y, Jun SY. Detection of post-stroke visual field loss by quantification of the retrogeniculate visual pathway. J Neurol Sci 2022; 439:120297. [DOI: 10.1016/j.jns.2022.120297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Revised: 04/28/2022] [Accepted: 05/22/2022] [Indexed: 11/28/2022]
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Park JG. Update on Stroke Rehabilitation for Non-Motor Impairment. BRAIN & NEUROREHABILITATION 2022; 15:e13. [PMID: 36743206 PMCID: PMC9833475 DOI: 10.12786/bn.2022.15.e13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/13/2022] [Accepted: 07/18/2022] [Indexed: 11/08/2022] Open
Abstract
Various interventions exist to treat non-motor impairments caused by stroke. Adjuvant treatments such as non-invasive brain stimulation, virtual reality, computer-assisted training, neurostimulation, and biofeedback are being investigated and applied in the areas of cognitive dysfunction, language problems, visual disorders, dysphagia, mood disorders, and post-stroke pain. Most of these treatments have shown efficacy and symptom improvement, but further investigation is required to fully clarify their effects.
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Affiliation(s)
- Jin Gee Park
- Department of Physical Medicine and Rehabilitation, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Korea
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10
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Urale PWB, Puckett AM, York A, Arnold D, Schwarzkopf DS. Highly accurate retinotopic maps of the physiological blind spot in human visual cortex. Hum Brain Mapp 2022; 43:5111-5125. [PMID: 35796159 PMCID: PMC9812231 DOI: 10.1002/hbm.25996] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 05/18/2022] [Accepted: 06/15/2022] [Indexed: 01/15/2023] Open
Abstract
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.
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Affiliation(s)
- Poutasi W. B. Urale
- School of Optometry & Vision ScienceUniversity of AucklandAucklandNew Zealand
| | - Alexander M. Puckett
- School of PsychologyUniversity of QueenslandBrisbaneQueenslandAustralia
- Queensland Brain InstituteUniversity of QueenslandBrisbaneQueenslandAustralia
| | - Ashley York
- School of PsychologyUniversity of QueenslandBrisbaneQueenslandAustralia
- Queensland Brain InstituteUniversity of QueenslandBrisbaneQueenslandAustralia
| | - Derek Arnold
- School of PsychologyUniversity of QueenslandBrisbaneQueenslandAustralia
- Queensland Brain InstituteUniversity of QueenslandBrisbaneQueenslandAustralia
| | - D. Samuel Schwarzkopf
- School of Optometry & Vision ScienceUniversity of AucklandAucklandNew Zealand
- Experimental PsychologyUniversity College LondonLondonUnited Kingdom
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11
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Cavanaugh MR, Tadin D, Carrasco M, Huxlin KR. Benefits of Endogenous Spatial Attention During Visual Double-Training in Cortically-Blinded Fields. Front Neurosci 2022; 16:771623. [PMID: 35495043 PMCID: PMC9046589 DOI: 10.3389/fnins.2022.771623] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 03/08/2022] [Indexed: 12/12/2022] Open
Abstract
Recovery of visual discrimination thresholds inside cortically-blinded (CB) fields is most commonly attained at a single, trained location at a time, with iterative progress deeper into the blind field as performance improves over several months. As such, training is slow, inefficient, burdensome, and often frustrating for patients. Here, we investigated whether double-location training, coupled with a covert spatial-attention (SA) pre-cue, could improve the efficiency of training. Nine CB participants completed a randomized, training assignment with either a spatial attention or neutral pre-cue. All trained for a similar length of time on a fine direction discrimination task at two blind field locations simultaneously. Training stimuli and tasks for both cohorts were identical, save for the presence of a central pre-cue, to manipulate endogenous (voluntary) SA, or a Neutral pre-cue. Participants in the SA training cohort demonstrated marked improvements in direction discrimination thresholds, albeit not to normal/intact-field levels; participants in the Neutral training cohort remained impaired. Thus, double-training within cortically blind fields, when coupled with SA pre-cues can significantly improve direction discrimination thresholds at two locations simultaneously, offering a new method to improve performance and reduce the training burden for CB patients. Double-training without SA pre-cues revealed a hitherto unrecognized limitation of cortically-blind visual systems’ ability to improve while processing two stimuli simultaneously. These data could potentially explain why exposure to the typically complex visual environments encountered in everyday life is insufficient to induce visual recovery in CB patients. It is hoped that these new insights will direct both research and therapeutic developments toward methods that can attain better, faster recovery of vision in CB fields.
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Affiliation(s)
- Matthew R. Cavanaugh
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
| | - Duje Tadin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
- Department of Brain and Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, NY, United States
| | - Marisa Carrasco
- Department of Psychology and Center for Neural Science, New York University, New York, NY, United States
| | - Krystel R. Huxlin
- Flaum Eye Institute and Center for Visual Science, University of Rochester, Rochester, NY, United States
- Department of Brain and Cognitive Sciences and Center for Visual Science, University of Rochester, Rochester, NY, United States
- *Correspondence: Krystel R. Huxlin,
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12
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Derrien D, Garric C, Sergent C, Chokron S. The nature of blindsight: implications for current theories of consciousness. Neurosci Conscious 2022; 2022:niab043. [PMID: 35237447 PMCID: PMC8884361 DOI: 10.1093/nc/niab043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 11/08/2021] [Accepted: 01/13/2022] [Indexed: 11/16/2022] Open
Abstract
Blindsight regroups the different manifestations of preserved discriminatory visual capacities following the damage to the primary visual cortex. Blindsight types differentially impact objective and subjective perception, patients can report having no visual awareness whilst their behaviour suggests visual processing still occurs at some cortical level. This phenomenon hence presents a unique opportunity to study consciousness and perceptual consciousness, and for this reason, it has had an historical importance for the development of this field of research. From these studies, two main opposing models of the underlying mechanisms have been established: (a) blindsight is perception without consciousness or (b) blindsight is in fact degraded vision, two views that mirror more general theoretical options about whether unconscious cognition truly exists or whether it is only a degraded form of conscious processing. In this article, we want to re-examine this debate in the light of recent advances in the characterization of blindsight and associated phenomena. We first provide an in-depth definition of blindsight and its subtypes, mainly blindsight type I, blindsight type II and the more recently described blindsense. We emphasize the necessity of sensitive and robust methodology to uncover the dissociations between perception and awareness that can be observed in brain-damaged patients with visual field defects at different cognitive levels. We discuss these different profiles of dissociation in the light of both contending models. We propose that the different types of dissociations reveal a pattern of relationship between perception, awareness and metacognition that is actually richer than what is proposed by either of the existing models. Finally, we consider this in the framework of current theories of consciousness and touch on the implications the findings of blindsight have on these.
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Affiliation(s)
- Diane Derrien
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Rothschild, Paris 75019, France
| | - Clémentine Garric
- Inserm, CHU Lille, U1172—LilNCog (JPARC)—Lille Neuroscience & Cognition, University of Lille, Lille 59000, France
| | - Claire Sergent
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
| | - Sylvie Chokron
- Integrative Neuroscience and Cognition Center, UMR 8002, CNRS & Université de Paris, Paris 75006, France
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Rothschild, Paris 75019, France
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Spared perilesional V1 activity underlies training-induced recovery of luminance detection sensitivity in cortically-blind patients. Nat Commun 2021; 12:6102. [PMID: 34671032 PMCID: PMC8528839 DOI: 10.1038/s41467-021-26345-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 09/29/2021] [Indexed: 11/19/2022] Open
Abstract
Damage 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. In humans, stroke damage to V1 causes large visual field defects. Spared V1 activity prior to training predicts the amount of training-induced recovery in luminance detection sensitivity. Moreover, visual training changes population receptive field properties within residual V1 circuits.
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