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Bonfanti D, Mazzi C, Savazzi S. Mapping the routes of perception: Hemispheric asymmetries in signal propagation dynamics. Psychophysiology 2024; 61:e14529. [PMID: 38279560 DOI: 10.1111/psyp.14529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 12/14/2023] [Accepted: 01/11/2024] [Indexed: 01/28/2024]
Abstract
The visual system has long been considered equivalent across hemispheres. However, an increasing amount of data shows that functional differences may exist in this regard. We therefore tried to characterize the emergence of visual perception and the spatiotemporal dynamics resulting from the stimulation of visual cortices in order to detect possible interhemispheric asymmetries. Eighteen participants were tested. Each of them received 360 transcranial magnetic stimulation (TMS) pulses at phosphene threshold intensity over left and right early visual areas while electroencephalography was being recorded. After each single pulse, participants had to report the presence or absence of a phosphene. Local mean field power analysis of TMS-evoked potentials showed an effect of both site (left vs. right TMS) of stimulation and hemisphere (ipsilateral vs. contralateral to the TMS): while right TMS determined early stronger activations, left TMS determined later stronger activity in contralateral electrodes. The interhemispheric signal propagation index revealed differences in how TMS-evoked activity spreads: left TMS-induced activity diffused contralaterally more than right stimulation. With regard to phosphenes perception, distinct electrophysiological patterns were found to reflect similar perceptual experiences: left TMS-evoked phosphenes are associated with early occipito-parietal and frontal activity followed by late central activity; right TMS-evoked phosphenes determine only late, fronto-central, and parietal activations. Our results show that left and right occipital TMS elicits differential electrophysiological patterns in the brain, both per se and as a function of phosphene perception. These distinct activation patterns may suggest a different role of the two hemispheres in processing visual information and giving rise to perception.
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Affiliation(s)
- Davide Bonfanti
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Chiara Mazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Silvia Savazzi
- Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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2
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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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3
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Xu J, Schoenfeld MA, Rossini PM, Tatlisumak T, Nürnberger A, Antal A, He H, Gao Y, Sabel BA. Adaptive and maladaptive brain functional network reorganization after stroke in hemianopia patients: an EEG-tracking study. Brain Connect 2022; 12:725-739. [PMID: 35088596 DOI: 10.1089/brain.2021.0145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE Hemianopia following occipital stroke is believed to be mainly due to local damage at or near the lesion site. Yet, MRI studies suggest functional connectivity network (FCN) reorganization also in distant brain regions. Because it is unclear if reorganization is adaptive or maladaptive, compensating for, or aggravating vision loss, we characterized FCNs electrophysiologically to explore local and global brain plasticity and correlated FCN reorganization with visual performance. METHODS Resting-state EEG was recorded in chronic, unilateral stroke patients and healthy age-matched controls (n=24 each). The correlation of oscillating EEG activity was calculated with the imaginary part of coherence between pairs of interested regions, and FCN graph theory metrics (degree, strength, clustering coefficient) were correlated with stimulus detection and reaction time. RESULTS Stroke brains showed altered FCNs in the alpha- and beta-band in numerous occipital, temporal and frontal brain structures. On a global level, FCN had a less efficient network organization while on the local level node networks reorganized especially in the intact hemisphere. Here, the occipital network was 58% more rigid (with a more "regular" network structure) while the temporal network was 32% more efficient (showing greater "small-worldness"), both of which correlated with worse or better visual processing, respectively. CONCLUSIONS Occipital stroke is associated with both local and global FCN reorganization, but this can be both, adaptive and maladaptive. We propose that the more "regular" FCN structure in the intact visual cortex indicates maladaptive plasticity where less processing efficacy with reduced signal/noise ratio may cause perceptual deficits in the intact visual field. In contrast, reorganization in intact temporal brain regions is presumably adaptive, possibly supporting enhanced peripheral movement perception.
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Affiliation(s)
- Jiahua Xu
- Otto von Guericke Universität Magdeburg, 9376, Magdeburg, Sachsen-Anhalt, Germany;
| | | | | | | | - Andreas Nürnberger
- Otto von Guericke Universität Magdeburg, 9376, Magdeburg, Sachsen-Anhalt, Germany;
| | - Andrea Antal
- University Medical Center Göttingen, 84922, Gottingen, Niedersachsen, Germany;
| | - Huiguang He
- Chinese Academy of Sciences Institute of Automation, 74522, Beijing, Beijing, China;
| | - Ying Gao
- Chinese Academy of Sciences Institute of Automation, 74522, Beijing, Beijing, China;
| | - Bernhard A Sabel
- Otto von Guericke Universität Magdeburg, 9376, Magdeburg, Sachsen-Anhalt, Germany;
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Geuzebroek AC, Woutersen K, van den Berg AV. When You Do Not Get the Whole Picture: Scene Perception After Occipital Cortex Lesions. Front Neurosci 2021; 15:716273. [PMID: 34966253 PMCID: PMC8710569 DOI: 10.3389/fnins.2021.716273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 11/08/2021] [Indexed: 11/29/2022] Open
Abstract
Background: Occipital cortex lesions (OCLs) typically result in visual field defects (VFDs) contralateral to the damage. VFDs are usually mapped with perimetry involving the detection of point targets. This, however, ignores the important role of integration of visual information across locations in many tasks of everyday life. Here, we ask whether standard perimetry can fully characterize the consequences of OCLs. We compare performance on a rapid scene discrimination task of OCL participants and healthy observers with simulated VFDs. While the healthy observers will only suffer the loss of part of the visual scene, the damage in the OCL participants may further compromise global visual processing. Methods: VFDs were mapped with Humphrey perimetry, and participants performed two rapid scene discrimination tasks. In healthy participants, the VFDs were simulated with hemi- and quadrant occlusions. Additionally, the GIST model, a computational model of scene recognition, was used to make individual predictions based on the VFDs. Results: The GIST model was able to predict the performance of controls regarding the effects of the local occlusion. Using the individual predictions of the GIST model, we can determine that the variability between the OCL participants is much larger than the extent of the VFD could account for. The OCL participants can further be categorized as performing worse, the same, or better as their VFD would predict. Conclusions: While in healthy observers the extent of the simulated occlusion accounts for their performance loss, the OCL participants' performance is not fully determined by the extent or shape of their VFD as measured with Humphrey perimetry. While some OCL participants are indeed only limited by the local occlusion of the scene, for others, the lesions compromised the visual network in a more global and disruptive way. Yet one outperformed a healthy observer, suggesting a possible adaptation to the VFD. Preliminary analysis of neuroimaging data suggests that damage to the lateral geniculate nucleus and corpus callosum might be associated with the larger disruption of rapid scene discrimination. We believe our approach offers a useful behavioral tool for investigating why similar VFDs can produce widely differing limitations in everyday life.
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Affiliation(s)
- Anna C. Geuzebroek
- Donders Institute for Brain, Cognition and Behavior, Center for Cognitive Neuroscience, Radboud University, Nijmegen, Netherlands
- School of Electrical and Electronic Engineering, University College Dublin, Dublin, Ireland
| | - Karlijn Woutersen
- Donders Institute for Brain, Cognition and Behavior, Center for Cognitive Neuroscience, Radboud University Medical Center (RadboudUMC), Nijmegen, Netherlands
| | - Albert V. van den Berg
- Donders Institute for Brain, Cognition and Behavior, Center for Cognitive Neuroscience, Radboud University Medical Center (RadboudUMC), Nijmegen, Netherlands
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Pedersini CA, Lingnau A, Sanchez-Lopez J, Cardobi N, Savazzi S, Marzi CA. Visuo-spatial attention to the blind hemifield of hemianopic patients: Can it survive the impairment of visual awareness? Neuropsychologia 2020; 149:107673. [PMID: 33186572 DOI: 10.1016/j.neuropsychologia.2020.107673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 10/13/2020] [Accepted: 11/04/2020] [Indexed: 12/21/2022]
Abstract
The general aim of this study was to assess the effect produced by visuo-spatial attention on both behavioural performance and brain activation in hemianopic patients following visual stimulus presentation to the blind hemifield. To do that, we tested five hemianopic patients and six age-matched healthy controls in an MRI scanner during the execution of a Posner-like paradigm using a predictive central cue. Participants were instructed to covertly orient attention toward the blind or sighted hemifield in different blocks while discriminating the orientation of a visual grating. In patients, we found significantly faster reaction times (RT) in valid and neutral than invalid trials not only in the sighted but also in the blind hemifield, despite the impairment of consciousness and performance at chance. As to the fMRI signal, in valid trials we observed the activation of ipsilesional visual areas (mainly lingual gyrus - area 19) during the orientation of attention toward the blind hemifield. Importantly, this activation was similar in patients and controls. In order to assess the related functional network, we performed a psychophysiological interactions (PPI) analysis that revealed an increased functional connectivity (FC) in patients with respect to controls between the ipsilesional lingual gyrus and ipsilateral fronto-parietal as well as contralesional parietal regions. Moreover, the shift of attention from the blind to the sighted hemifield revealed stronger FC between the contralesional visual areas V3/V4 and ipsilateral parietal regions in patients than controls. These results indicate a higher cognitive effort in patients when paying attention to the blind hemifiled or when shifting attention from the blind to the sighted hemfield, possibly as an attempt to compensate for the visual loss. Taken together, these results show that hemianopic patients can covertly orient attention toward the blind hemifield with a top-down mechanism by activating a functional network mainly including fronto-parietal regions belonging to the dorsal attentional network.
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Affiliation(s)
- Caterina A Pedersini
- Physiology and Psychology Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy.
| | - Angelika Lingnau
- Faculty of Psychology, Education and Sport Science, Institute of Psychology, University of Regensburg, Germany; Centre For Mind/Brain Sciences (CIMeC), University of Trento, Italy
| | - Javier Sanchez-Lopez
- Physiology and Psychology Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Nicolo Cardobi
- Physiology and Psychology Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Silvia Savazzi
- Physiology and Psychology Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy
| | - Carlo A Marzi
- Physiology and Psychology Section, Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Verona, Italy; National Institute of Neuroscience, Verona, Italy
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Abstract
OBJECTIVE Both clinically observable and subclinical hemispatial neglect are related to functional disability. The aim of the present study was to examine whether increasing task complexity improves sensitivity in assessment and whether it enables the identification of subclinical neglect. METHOD We developed and compared two computerized dual-tasks, a simpler and a more complex one, and presented them on a large, 173 × 277 cm screen. Participants in the study included 40 patients with unilateral stroke in either the left hemisphere (LH patient group, n = 20) or the right hemisphere (RH patient group, n = 20) and 20 healthy controls. In addition to the large-screen tasks, all participants underwent a comprehensive neuropsychological assessment. The Bells Test was used as a traditional paper-and-pencil cancellation test to assess neglect. RESULTS RH patients made significantly more left hemifield omission errors than controls in both large-screen tasks. LH patients' omissions did not differ significantly from those of the controls in either large-screen task. No significant group differences were observed in the Bells Test. All groups' reaction times were significantly slower in the more complex large-screen task compared to the simpler one. The more complex large-screen task also produced significantly slower reactions to stimuli in the left than in the right hemifield in all groups. CONCLUSIONS The present results suggest that dual-tasks presented on a large screen sensitively reveal subclinical neglect in stroke. New, sensitive, and ecologically valid methods are needed to evaluate subclinical neglect.
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7
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Kovarski K, Caetta F, Mermillod M, Peyrin C, Perez C, Granjon L, Delorme R, Cartigny A, Zalla T, Chokron S. Emotional face recognition in autism and in cerebral visual impairments: In search for specificity. J Neuropsychol 2020; 15:235-252. [PMID: 32920927 DOI: 10.1111/jnp.12221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/15/2020] [Indexed: 12/16/2022]
Abstract
Autism spectrum disorder (ASD) is characterized by difficulties in the social domain, but also by hyper- and hypo-reactivity. Atypical visual behaviours and processing have often been observed. Nevertheless, several similar signs are also identified in other clinical conditions including cerebral visual impairments (CVI). In the present study, we investigated emotional face categorization in groups of children with ASD and CVI by comparing each group to typically developing individuals (TD) in two tasks. Stimuli were either non-filtered or filtered by low- and high-spatial frequencies (LSF and HSF). All participants completed the autism spectrum quotient score (AQ) and a complete neurovisual evaluation. The results show that while both clinical groups presented difficulties in the emotional face recognition tasks and atypical processing of filtered stimuli, they did not differ from one another. Additionally, autistic traits were observed in the CVI group and symmetrically, some visual disturbances were present in the ASD group as measured via the AQ score and a neurovisual evaluation, respectively. The present study suggests the relevance of comparing ASD to CVI by showing that emotional face categorization difficulties should not be solely considered as autism-specific but merit investigation for potential dysfunction of the visual processing neural network. These results are of interest in both clinical and research perspectives, indicating that systematic visual examination is warranted for individuals with ASD.
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Affiliation(s)
- Klara Kovarski
- Institut de Neuropsychologie, Neurovision et Neurocognition, Hôpital Fondation Rothschild, Paris, France.,Université de Paris, CNRS, Integrative Neuroscience and Cognition Center, Paris, France, Paris, France
| | - Florent Caetta
- Institut de Neuropsychologie, Neurovision et Neurocognition, Hôpital Fondation Rothschild, Paris, France
| | - Martial Mermillod
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LPNC, Grenoble, France
| | - Carole Peyrin
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, LPNC, Grenoble, France
| | - Céline Perez
- Institut de Neuropsychologie, Neurovision et Neurocognition, Hôpital Fondation Rothschild, Paris, France
| | - Lionel Granjon
- Université de Paris, CNRS, Integrative Neuroscience and Cognition Center, Paris, France, Paris, France
| | - Richard Delorme
- Department of Child and Adolescent Psychiatry, Assistance Publique-Hôpitaux de Paris, Robert Debré Hospital, Paris, France
| | - Ariane Cartigny
- Institut de Neuropsychologie, Neurovision et Neurocognition, Hôpital Fondation Rothschild, Paris, France.,Université de Paris, CNRS, Integrative Neuroscience and Cognition Center, Paris, France, Paris, France
| | - Tiziana Zalla
- Institut Jean Nicod, CNRS, Ecole Normale Supérieure, Paris, France
| | - Sylvie Chokron
- Institut de Neuropsychologie, Neurovision et Neurocognition, Hôpital Fondation Rothschild, Paris, France.,Université de Paris, CNRS, Integrative Neuroscience and Cognition Center, Paris, France, Paris, France
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8
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Halbertsma HN, Elshout JA, Bergsma DP, Norris DG, Cornelissen FW, van den Berg AV, Haak KV. Functional connectivity of the Precuneus reflects effectiveness of visual restitution training in chronic hemianopia. Neuroimage Clin 2020; 27:102292. [PMID: 32554320 PMCID: PMC7303670 DOI: 10.1016/j.nicl.2020.102292] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 04/17/2020] [Accepted: 05/19/2020] [Indexed: 01/10/2023]
Abstract
Visual field defects in chronic hemianopia can improve through visual restitution training, yet not all patients benefit equally from this long and exhaustive procedure. Here, we asked if resting-state functional connectivity prior to visual restitution could predict training success. In two training sessions of eight weeks each, 20 patients with chronic hemianopia performed a visual discrimination task by directing spatial selective attention towards stimuli presented in either hemifield, while suppressing eye movements. We examined two effects: a sensitivity change in the attended (trained) minus the unattended (control) hemifield (i.e., a training-specific improvement), and an overall improvement (i.e., a total change in sensitivity after both sessions). We then identified five visual resting-state networks and evaluated their functional connectivity in relation to both training effects. We found that the functional connectivity strength between the anterior Precuneus and the Occipital Pole Network was positively related to the attention modulated (i.e., training-specific) improvement. No such relationship was found for the overall improvement or for the other visual networks of interest. Our finding suggests that the anterior Precuneus plays a role in attention-modulated visual field improvements. The resting-state functional connectivity between the anterior Precuneus and the Occipital Pole Network may thus serve as an imaging-based biomarker that quantifies a patient's potential capacity to direct spatial attention. This may help to identify hemianopia patients that are most likely to benefit from visual restitution training.
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Affiliation(s)
- Hinke N Halbertsma
- Laboratory for Experimental Ophthalmology, University Medical Center Groningen, Groningen, the Netherlands.
| | - Joris A Elshout
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Douwe P Bergsma
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - David G Norris
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Frans W Cornelissen
- Laboratory for Experimental Ophthalmology, University Medical Center Groningen, Groningen, the Netherlands
| | - Albert V van den Berg
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Koen V Haak
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, the Netherlands
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9
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Chokron S, Dubourg L, Garric C, Martinelli F, Perez C. Dissociations between perception and awareness in hemianopia. Restor Neurol Neurosci 2020; 38:189-201. [PMID: 31929128 DOI: 10.3233/rnn-190951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby patients are blind to the contralesional visual field of each eye. Homonymous hemianopia has been studied in terms of its deleterious consequences on perceptual, cognitive and motor tasks as well as because it represents an interesting model of vision loss after a unilateral lesion of the occipital lobe. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, HH patients can also exhibit dissociations between perception and awareness. Firstly, HH patients suffering from anosognosia may be unaware of their visual field defect. Secondly, HH patients can present with unconscious visual abilities in the blind hemifield, a phenomenon referred to as blindsight. Thirdly, recent reports demonstrate that HH patients can suffer from a subtle deficit in their ipsilesional visual field that they are unaware of, a condition called sightblindness (i.e. the reverse case of 'blindsight'). Finally, HH patients may also exhibit visual hallucinations in their blind field; however, such patients are not systematically aware that their perceptions are unreal. In this review, we provide an overview of the visual-field losses in HH patients after a left or right unilateral occipital lesion. Furthermore, we explore the implications of these four phenomena for models of visual processing and rehabilitation of visual field defects in HH patients. Finally, in contrast to the traditional view that HH is solely a visual-field defect, we discuss why this deficit is an interesting model for studying the dissociation between perception and awareness.
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Affiliation(s)
- Sylvie Chokron
- Integrative Neuroscience and Cognition Center, CNRS, UMR 8242 et Université Paris-Descartes, Paris, France
| | - Lucas Dubourg
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Integrative Neuroscience and Cognition Center, CNRS, UMR 8242 et Université Paris-Descartes, Paris, France
| | - Clémentine Garric
- Laboratoire de Sciences Cognitives et Affectives, SCALab, CNRS UMR, Faculté de Médecine, Pôle Recherche et Université de Lille, Lille, France
| | - Fiora Martinelli
- Integrative Neuroscience and Cognition Center, CNRS, UMR 8242 et Université Paris-Descartes, Paris, France
| | - Céline Perez
- Institut de Neuropsychologie, Neurovision, NeuroCognition, Fondation Ophtalmologique Adolphe de Rothschild, Paris, France.,Integrative Neuroscience and Cognition Center, CNRS, UMR 8242 et Université Paris-Descartes, Paris, France
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10
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Garric C, Sebaa A, Caetta F, Perez C, Savatovsky J, Sergent C, Chokron S. Dissociation between objective and subjective perceptual experiences in a population of hemianopic patients: A new form of blindsight? Cortex 2019; 117:299-310. [PMID: 31181393 DOI: 10.1016/j.cortex.2019.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/06/2019] [Accepted: 05/05/2019] [Indexed: 01/05/2023]
Abstract
After a post-chiasmatic lesion, some patients may retain unconscious visual function, known as blindsight, in their contralesional visual field. Despite the importance of blindsight in the study of consciousness, little is known about the nature of patients' experience in their hemianopic field. To address this knowledge gap, we measured blindsight, and assessed the perceptual experience in the contralesional visual field, of seventeen homonymous hemianopic (HH) patients. To ensure that the stimuli were shown in a "blind" sector of the visual field, we selected a subgroup of eight complete-HH patients, as determined by automatic perimetry. Firstly, we measured blindsight through a forced-choice task in which the patients had to identify letters displayed on a screen. Secondly, we compared the patients' binary responses ("Something was presented" vs "Nothing was presented") to responses on a new, five-level scale, the Sensation Awareness Scale (SAS), which we designed to include visual as well as non-visual answers (e.g., "I felt something"). Interestingly, only one of the eight complete-HH patients met the criteria for blindsight. More importantly, our SAS enabled us to identify a previously unreported dissociation, which we have named blindsense, in four of the eight complete-HH patients. Specifically, these four patients exhibited better-than-chance sensitivity to the presence of a stimulus on the subjective scale, despite being unable to identify the stimulus during the forced-choice task. Our findings highlight the importance of awareness-assessment methods to investigate perceptual experiences in the contralesional visual field and suggest a low incidence of blindsight in post-stroke HH patients.
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Affiliation(s)
- Clémentine Garric
- Unité Vision et Cognition, Fondation Ophtalmologique de Rothschild, Paris, France; Laboratoire de Psychologie de la Perception, UMR 8242, CNRS & Université Paris-Descartes, Paris, France
| | - Aïda Sebaa
- Unité Vision et Cognition, Fondation Ophtalmologique de Rothschild, Paris, France
| | - Florent Caetta
- Unité Vision et Cognition, Fondation Ophtalmologique de Rothschild, Paris, France
| | - Céline Perez
- Unité Vision et Cognition, Fondation Ophtalmologique de Rothschild, Paris, France; Service de Neurologie, Fondation Ophtalmologique Rothschild, Paris, France
| | - Julien Savatovsky
- Service d'Imagerie, Fondation Ophtalmologique Rothschild, Paris, France
| | - Claire Sergent
- Laboratoire de Psychologie de la Perception, UMR 8242, CNRS & Université Paris-Descartes, Paris, France
| | - Sylvie Chokron
- Unité Vision et Cognition, Fondation Ophtalmologique de Rothschild, Paris, France; Laboratoire de Psychologie de la Perception, UMR 8242, CNRS & Université Paris-Descartes, Paris, France; Service de Neurologie, Fondation Ophtalmologique Rothschild, Paris, France.
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11
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Chokron S, Peyrin C, Perez C. Ipsilesional deficit of selective attention in left homonymous hemianopia and left unilateral spatial neglect. Neuropsychologia 2019; 128:305-314. [DOI: 10.1016/j.neuropsychologia.2018.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 03/06/2018] [Accepted: 03/08/2018] [Indexed: 12/23/2022]
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12
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Sanchez-Lopez J, Pedersini CA, Di Russo F, Cardobi N, Fonte C, Varalta V, Prior M, Smania N, Savazzi S, Marzi CA. Visually evoked responses from the blind field of hemianopic patients. Neuropsychologia 2019; 128:127-139. [PMID: 28987906 PMCID: PMC5845440 DOI: 10.1016/j.neuropsychologia.2017.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 11/28/2022]
Abstract
Hemianopia is a visual field defect characterized by decreased vision or blindness in the contralesional visual field of both eyes. The presence of well documented above-chance unconscious behavioural responses to visual stimuli presented to the blind hemifield (blindsight) has stimulated a great deal of research on the neural basis of this important phenomenon. The present study is concerned with electrophysiological responses from the blind field. Since previous studies found that transient Visual Evoked Potentials (VEPs) are not entirely suitable for this purpose here we propose to use Steady-State VEPs (SSVEPs). A positive result would have important implications for the understanding of the neural bases of conscious vision. We carried out a passive SSVEP stimulation with healthy participants and hemianopic patients. Stimuli consisted of four black-and-white sinusoidal Gabor gratings presented one in each visual field quadrant and flickering one at a time at a 12Hz rate. To assess response reliability a Signal-to-Noise Ratio analysis was conducted together with further analyses in time and frequency domains to make comparisons between groups (healthy participants and patients), side of brain lesion (left and right) and visual fields (sighted and blind). The important overall result was that stimulus presentation to the blind hemifield yielded highly reliable responses with time and frequency features broadly similar to those found for cortical extrastriate areas in healthy controls. Moreover, in the intact hemifield of hemianopics and in healthy controls there was evidence of a role of prefrontal structures in perceptual awareness. Finally, the presence of different patterns of brain reorganization depended upon the side of lesion.
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Affiliation(s)
- Javier Sanchez-Lopez
- Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy.
| | - Caterina A Pedersini
- Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy
| | - Francesco Di Russo
- Department. of Movement, Human and Health Sciences, University of Rome "Foro Italico", Rome, Italy; IRCCS Santa Lucia Foundation, Rome, Italy
| | - Nicolò Cardobi
- Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy
| | - Cristina Fonte
- Neuromotor and Cognitive Rehabilitation Research Center, Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy
| | - Valentina Varalta
- Neuromotor and Cognitive Rehabilitation Research Center, Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy
| | | | - Nicola Smania
- Neuromotor and Cognitive Rehabilitation Research Center, Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy
| | - Silvia Savazzi
- Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy; Perception and Awareness (PandA) Laboratory, Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy; National Institute of Neuroscience, Verona, Italy
| | - Carlo A Marzi
- Department of Neuroscience, Biomedicine and Movement, University of Verona, Italy; National Institute of Neuroscience, Verona, Italy
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Hemianopia and Features of Bálint Syndrome following Occipital Lobe Hemorrhage: Identification and Patient Understanding Have Aided Functional Improvement Years after Onset. Case Rep Ophthalmol Med 2019; 2019:3864572. [PMID: 31019823 PMCID: PMC6452550 DOI: 10.1155/2019/3864572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 02/17/2019] [Accepted: 03/06/2019] [Indexed: 11/17/2022] Open
Abstract
Introduction. Cerebral visual impairment (CVI) can present around birth or any time thereafter. Homonymous hemianopia is a common feature. The concept that functional improvement is unattainable augurs against active management. Dorsal stream dysfunction (or Bálint syndrome when severe) results from bilateral posterior parietal dysfunction but may go undetected, especially in children. Case Presentation. At 16 the patient suffered spontaneous left occipital lobe brain hemorrhage from a ruptured arteriovenous malformation. This was surgically excised. Short lived right upper limb intermittent jerking, with additional left sided weakness, ensued. Anomalous EEG recordings, with right-sided bias, arose from the posterior temporoparietal area. A right homonymous hemianopia was evident. During the ensuing 17 years she experienced multiple complex difficulties, until, at a lecture describing how to identify and support children with CVI, she realized she herself had many of the difficulties described. Visual assessment identified hemianopia and dorsal stream dysfunction. Discussion. Following identification, characterization, and explanation of the impact of her visual difficulties, she both gained greater awareness of her visual difficulties and their impact and developed a range of strategies leading to functional improvement of her visual field loss and amelioration of her dorsal stream dysfunction, with great improvement in quality of life.
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14
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Paramei GV, Favrod O, Sabel BA, Herzog MH. Pathological completion in the intact visual field of hemianopia patients. VISUAL COGNITION 2017. [DOI: 10.1080/13506285.2017.1352056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
| | - Ophélie Favrod
- Laboratory of Psychophysics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Bernhard A. Sabel
- Institute of Medical Psychology, Otto-von-Guericke University of Magdeburg, Magdeburg, Germany
| | - Michael H. Herzog
- Laboratory of Psychophysics, Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
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15
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Geuzebroek AC, van den Berg AV. Impaired visual competition in patients with homonymous visual field defects. Neuropsychologia 2017; 97:152-162. [PMID: 28209521 DOI: 10.1016/j.neuropsychologia.2017.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 02/06/2017] [Accepted: 02/12/2017] [Indexed: 10/20/2022]
Abstract
Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events. Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the 'intact' visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed. Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients' supposedly 'intact' visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions. The present results indicate that patients and controls have similar decision-making mechanisms but patients' choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also include training focused on improving visual decision-making of the defective and the intact visual field.
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Affiliation(s)
- A C Geuzebroek
- Department Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Postbus 9101, 6500 HB Nijmegen (route 205), The Netherlands.
| | - A V van den Berg
- Department Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Postbus 9101, 6500 HB Nijmegen (route 205), The Netherlands.
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Ajina S, Bridge H. Blindsight and Unconscious Vision: What They Teach Us about the Human Visual System. Neuroscientist 2016; 23:529-541. [PMID: 27777337 DOI: 10.1177/1073858416673817] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Damage to the primary visual cortex removes the major input from the eyes to the brain, causing significant visual loss as patients are unable to perceive the side of the world contralateral to the damage. Some patients, however, retain the ability to detect visual information within this blind region; this is known as blindsight. By studying the visual pathways that underlie this residual vision in patients, we can uncover additional aspects of the human visual system that likely contribute to normal visual function but cannot be revealed under physiological conditions. In this review, we discuss the residual abilities and neural activity that have been described in blindsight and the implications of these findings for understanding the intact system.
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Affiliation(s)
- Sara Ajina
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Holly Bridge
- 1 Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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Chokron S, Perez C, Peyrin C. Behavioral Consequences and Cortical Reorganization in Homonymous Hemianopia. Front Syst Neurosci 2016; 10:57. [PMID: 27445717 PMCID: PMC4923162 DOI: 10.3389/fnsys.2016.00057] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/13/2016] [Indexed: 12/16/2022] Open
Abstract
The most common visual defect to follow a lesion of the retrochiasmal pathways is homonymous hemianopia (HH), whereby, in each eye, patients are blind to the contralesional visual field. From a behavioral perspective, in addition to exhibiting a severe deficit in their contralesional visual field, hemianopic patients can also present implicit residual capacities, now usually referred to collectively as blindsight. It was recently demonstrated that HH patients can also suffer from a subtle deficit in their ipsilesional visual field, called sightblindness (the reverse case of blindsight). Furthermore, the nature of the visual deficit in the contralesional and ipsilesional visual fields, as well as the pattern of functional reorganization in the occipital lobe of HH patients after stroke, all appear to depend on the lesion side. In addition to their contralesional and ipsilesional visual deficits, and to their residual capacities, HH patients can also experience visual hallucinations in their blind field, the physiopathological mechanisms of which remain poorly understood. Herein we review blindsight in terms of its better-known aspects as well as its less-studied clinical signs such as sightblindness, hemispheric specialization and visual hallucinations. We also discuss the implications of recent experimental findings for rehabilitation of visual field defects in hemianopic patients.
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Affiliation(s)
- Sylvie Chokron
- Unité Fonctionnelle Vision and Cognition, Fondation Ophtalmologique RothschildParis, France; UMR 8242, Laboratoire de Psychologie de la Perception, CNRS and Université Paris-DescartesParis, France
| | - Céline Perez
- Unité Fonctionnelle Vision and Cognition, Fondation Ophtalmologique RothschildParis, France; UMR 8242, Laboratoire de Psychologie de la Perception, CNRS and Université Paris-DescartesParis, France
| | - Carole Peyrin
- UMR 5105, CNRS, Laboratoire de Psychologie et NeuroCognition, Université Grenoble Alpes Grenoble, France
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