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Danckert J, Striemer C, Rossetti Y. Blindsight. HANDBOOK OF CLINICAL NEUROLOGY 2021; 178:297-310. [PMID: 33832682 DOI: 10.1016/b978-0-12-821377-3.00016-7] [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: 12/24/2022]
Abstract
For over a century, research has demonstrated that damage to primary visual cortex does not eliminate all capacity for visual processing in the brain. From Riddoch's (1917) early demonstration of intact motion processing for blind field stimuli, to the iconic work of Weiskrantz et al. (1974) showing reliable spatial localization, it is clear that secondary visual pathways that bypass V1 carry information to the visual brain that in turn influences behavior. In this chapter, we briefly outline the history and phenomena associated with blindsight, before discussing the nature of the secondary visual pathways that support residual visual processing in the absence of V1. We finish with some speculation as to the functional characteristics of these secondary pathways.
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Affiliation(s)
- James Danckert
- Department of Psychology, University of Waterloo, Waterloo, ON, Canada.
| | | | - Yves Rossetti
- Trajectoires, Centre de Recherche en Neurosciences de Lyon, Inserm, CNRS, Université Lyon 1, Bron, France; Plateforme "Mouvement et Handicap", Hôpital Henry-Gabrielle, Hospices Civils de Lyon, Saint-Genis-Laval, France
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2
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The development of vision between nature and nurture: clinical implications from visual neuroscience. Childs Nerv Syst 2020; 36:911-917. [PMID: 32140777 DOI: 10.1007/s00381-020-04554-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 02/27/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND Vision is an adaptive function and should be considered a prerequisite for neurodevelopment because it permits the organization and the comprehension of the sensory data collected by the visual system during daily life. For this reason, the influence of visual functions on neuromotor, cognitive, and emotional development has been investigated by several studies that have highlighted how visual functions can drive the organization and maturation of human behavior. Recent studies on animals and human models have indicated that visual functions mature gradually during post-natal life, and its development is closely linked to environment and experience. DISCUSSION The role of vision in early brain development and some of the neuroplasticity mechanisms that have been described in the presence of cerebral damage during childhood are analyzed in this review, according to a neurorehabilitation prospective.
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Jiang H, Rowland BA, Stein BE. Reversing Hemianopia by Multisensory Training Under Anesthesia. Front Syst Neurosci 2020; 14:4. [PMID: 32076401 PMCID: PMC7006460 DOI: 10.3389/fnsys.2020.00004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/13/2020] [Indexed: 02/04/2023] Open
Abstract
Hemianopia is characterized by blindness in one half of the visual field and is a common consequence of stroke and unilateral injury to the visual cortex. There are few effective rehabilitative strategies that can relieve it. Using the cat as an animal model of hemianopia, we found that blindness induced by lesions targeting all contiguous areas of the visual cortex could be rapidly reversed by a non-invasive, multisensory (auditory-visual) exposure procedure even while animals were anesthetized. Surprisingly few trials were required to reinstate vision in the previously blind hemisphere. That rehabilitation was possible under anesthesia indicates that the visuomotor behaviors commonly believed to be essential are not required for this recovery, nor are factors such as attention, motivation, reward, or the various other cognitive features that are generally thought to facilitate neuro-rehabilitative therapies.
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Affiliation(s)
- Huai Jiang
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, United States
| | - Benjamin A Rowland
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, United States
| | - Barry E Stein
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, United States
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4
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Robust Visual Responses and Normal Retinotopy in Primate Lateral Geniculate Nucleus following Long-term Lesions of Striate Cortex. J Neurosci 2018; 38:3955-3970. [PMID: 29555856 DOI: 10.1523/jneurosci.0188-18.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/04/2018] [Accepted: 03/10/2018] [Indexed: 11/21/2022] Open
Abstract
Lesions of striate cortex (V1) trigger massive retrograde degeneration of neurons in the LGN. In primates, these lesions also lead to scotomas, within which conscious vision is abolished. Mediation of residual visual capacity within these regions (blindsight) has been traditionally attributed to an indirect visual pathway to the extrastriate cortex, which involves the superior colliculus and pulvinar complex. However, recent studies have suggested that preservation of the LGN is critical for behavioral evidence of blindsight, raising the question of what type of visual information is channeled by remaining neurons in this structure. A possible contribution of LGN neurons to blindsight is predicated on two conditions: that the neurons that survive degeneration remain visually responsive, and that their receptive fields continue to represent the region of the visual field inside the scotoma. We tested these conditions in male and female marmoset monkeys (Callithrix jacchus) with partial V1 lesions at three developmental stages (early postnatal life, young adulthood, old age), followed by long recovery periods. In all cases, recordings from the degenerated LGN revealed neurons with well-formed receptive fields throughout the scotoma. The responses were consistent and robust, and followed the expected eye dominance and retinotopy observed in the normal LGN. The responses had short latencies and preceded those of neurons recorded in the extrastriate middle temporal area. These findings suggest that the pathway that links LGN neurons to the extrastriate cortex is physiologically viable and can support residual vision in animals with V1 lesions incurred at various ages.SIGNIFICANCE STATEMENT Patients with a lesion of the primary visual cortex (V1) can retain certain visually mediated behaviors, particularly if the lesion occurs early in life. This phenomenon ("blindsight") not only sheds light on the nature of consciousness, but also has implications for studies of brain circuitry, development, and plasticity. However, the pathways that mediate blindsight have been the subject of debate. Recent studies suggest that projections from the LGN might be critical, but this finding is puzzling given that the lesions causes severe cell death in the LGN. Here we demonstrate in monkeys that the surviving LGN neurons retain a remarkable level of visual function and could therefore be the source of the visual information that supports blindsight.
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Bourne JA, Morrone MC. Plasticity of Visual Pathways and Function in the Developing Brain: Is the Pulvinar a Crucial Player? Front Syst Neurosci 2017; 11:3. [PMID: 28228719 PMCID: PMC5296321 DOI: 10.3389/fnsys.2017.00003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/23/2017] [Indexed: 11/29/2022] Open
Abstract
The pulvinar is the largest of the thalamic nuclei in the primates, including humans. In the primates, two of the three major subdivisions, the lateral and inferior pulvinar, are heavily interconnected with a significant proportion of the visual association cortex. However, while we now have a better understanding of the bidirectional connectivity of these pulvinar subdivisions, its functions remain somewhat of an enigma. Over the past few years, researchers have started to tackle this problem by addressing it from the angle of development and visual cortical lesions. In this review, we will draw together literature from the realms of studies in nonhuman primates and humans that have informed much of the current understanding. This literature has been responsible for changing many long-held opinions on the development of the visual cortex and how the pulvinar interacts dynamically with cortices during early life to ensure rapid development and functional capacity Furthermore, there is evidence to suggest involvement of the pulvinar following lesions of the primary visual cortex (V1) and geniculostriate pathway in early life which have far better functional outcomes than identical lesions obtained in adulthood. Shedding new light on the pulvinar and its role following lesions of the visual brain has implications for our understanding of visual brain disorders and the potential for recovery.
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Affiliation(s)
- James A Bourne
- Australian Regenerative Medicine Institute, Monash University Melbourne, VIC, Australia
| | - Maria Concetta Morrone
- Department of Translational Research on New Technologies in Medicine and Surgery, University of Pisa and IRCCS Stella Maris Foundation Pisa, Italy
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6
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Hagan MA, Rosa MGP, Lui LL. Neural plasticity following lesions of the primate occipital lobe: The marmoset as an animal model for studies of blindsight. Dev Neurobiol 2016; 77:314-327. [PMID: 27479288 DOI: 10.1002/dneu.22426] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 07/21/2016] [Accepted: 07/29/2016] [Indexed: 12/15/2022]
Abstract
For nearly a century it has been observed that some residual visually guided behavior can persist after damage to the primary visual cortex (V1) in primates. The age at which damage to V1 occurs leads to different outcomes, with V1 lesions in infancy allowing better preservation of visual faculties in comparison with those incurred in adulthood. While adult V1 lesions may still allow retention of some limited visual abilities, these are subconscious-a characteristic that has led to this form of residual vision being referred to as blindsight. The neural basis of blindsight has been of great interest to the neuroscience community, with particular focus on understanding the contributions of the different subcortical pathways and cortical areas that may underlie this phenomenon. More recently, research has started to address which forms of neural plasticity occur following V1 lesions at different ages, including work using marmoset monkeys. The relatively rapid postnatal development of this species, allied to the lissencephalic brains and well-characterized visual cortex provide significant technical advantages, which allow controlled experiments exploring visual function in the absence of V1. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 314-327, 2017.
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Affiliation(s)
- Maureen A Hagan
- Department of Physiology, Monash University, Victoria, 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Victoria, 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Victoria, 3800, Australia
| | - Marcello G P Rosa
- Department of Physiology, Monash University, Victoria, 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Victoria, 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Victoria, 3800, Australia
| | - Leo L Lui
- Department of Physiology, Monash University, Victoria, 3800, Australia.,Neuroscience Program, Biomedicine Discovery Institute, Monash University, Victoria, 3800, Australia.,Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Victoria, 3800, Australia
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Abstract
More vision is preserved after removal of primary visual cortex in infant than adult primates. A recent study suggests that this is due to the preservation of a retina-to-pulvinar-to-cortex pathway that normally regresses during development.
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Affiliation(s)
- Jon H Kaas
- Psychology Department, Vanderbilt University, 301 Wilson Hall, PMB 407817, 2301 Vanderbilt Place, Nashville, TN 37240-7817, USA.
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Tinelli F, Cicchini GM, Arrighi R, Tosetti M, Cioni G, Morrone MC. Blindsight in children with congenital and acquired cerebral lesions. Cortex 2013; 49:1636-47. [DOI: 10.1016/j.cortex.2012.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/28/2012] [Accepted: 07/24/2012] [Indexed: 10/28/2022]
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9
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Farah MJ, Rabinowitz C, Quinn GE, Liu GT. Early commitment of neural substrates for face recognition. Cogn Neuropsychol 2012; 17:117-23. [PMID: 20945175 DOI: 10.1080/026432900380526] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
We present evidence of a striking failure of plasticity in the neural substrates of face recognition, which suggests that the distinction between faces and other objects, and the localisation of faces relative to other objects, is fully determined prior to any postnatal experience. A boy who sustained brain damage at 1 day of age has the classic lesions and behavioural profile of adult-acquired prosopagnosia. He has profoundly impaired face recognition, whereas his recognition of objects is much less impaired. This implies that the human genome contains sufficiently explicit information about faces and nonface objects, or visual features by which they can be distinguished, that experience with these categories is not necessary for their functional delineation and differential brain localisation.
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Lane AR, Smith DT, Schenk T. Clinical treatment options for patients with homonymous visual field defects. Clin Ophthalmol 2011; 2:93-102. [PMID: 19668392 PMCID: PMC2698722 DOI: 10.2147/opth.s2371] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The objective of this review is to evaluate treatments for homonymous visual field defects (HVFDs). We distinguish between three treatments: visual restoration training (VRT), optical aids, and compensatory training. VRT is both the most ambitious and controversial approach, aiming to restore portions of the lost visual field. While early studies suggested that VRT can reduce the visual field defect, recent studies using more reliable means of monitoring the patients’ fixation could not confirm this effect. Studies utilizing modern optical aids have reported some promising results, but the extent to which these aids can reliably reduce the patients’ visual disability has yet to be confirmed. Compensatory approaches, which teach patients more effective ways of using their eyes, are currently the only form of treatment for which behavioral improvements have been demonstrated. However, with the exception of one study using a reading training, placebo-controlled clinical evaluation studies are lacking. It is also not yet clear whether the training benefits found in laboratory tasks lead to reliable improvements in activities of daily living and which of the various forms of compensatory training is the most promising. It is therefore too early to recommend any of the currently available treatment approaches.
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Affiliation(s)
- Alison R Lane
- Cognitive Neuroscience Research Unit, Durham University, Durham, UK
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11
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Stoerig P. Task-irrelevant blindsight and the impact of invisible stimuli. Front Psychol 2011; 2:66. [PMID: 21716576 PMCID: PMC3110775 DOI: 10.3389/fpsyg.2011.00066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2010] [Accepted: 03/29/2011] [Indexed: 11/13/2022] Open
Abstract
Despite their subjective invisibility, stimuli presented within regions of absolute cortical blindness can both guide forced-choice behavior when they are task-relevant and modulate responses to visible targets when they are task-irrelevant. We here tested three hemianopic patients to learn whether their performance in an attention-demanding rapid serial visual presentation task would be affected by task-irrelevant stimuli. Per trial, nine black letters and one white target letter appeared briefly at fixation; the white letter was to be named at the end of each trial. On 50% of trials, a task-irrelevant disk (-0.6 log contrast) was presented to the blind field; in separate blocks, the same or a very low negative contrast distractor was presented to the sighted field. Mean error rates were high and independent of distractor condition, although the high-contrast sighted-field disk impaired performance significantly in one participant. However, when trials with and without distractors were considered separately, performance was most impaired by the high-contrast disk in the blind field, whereas the same disk in the sighted field had no effect. As this disk was least visible in the blind and most visible in the sighted field, attentional suppression was inversely related to visibility. We suggest that visual awareness, or the processes that generate it and are compromised in the blind hemisphere, enhances or enables effective attentional suppression.
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Affiliation(s)
- Petra Stoerig
- Institute of Experimental Psychology II, Heinrich-Heine-University Dusseldorf Dusseldorf, Germany
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12
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13
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Vision restoration after brain and retina damage: the "residual vision activation theory". PROGRESS IN BRAIN RESEARCH 2011; 192:199-262. [PMID: 21763527 DOI: 10.1016/b978-0-444-53355-5.00013-0] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vision loss after retinal or cerebral visual injury (CVI) was long considered to be irreversible. However, there is considerable potential for vision restoration and recovery even in adulthood. Here, we propose the "residual vision activation theory" of how visual functions can be reactivated and restored. CVI is usually not complete, but some structures are typically spared by the damage. They include (i) areas of partial damage at the visual field border, (ii) "islands" of surviving tissue inside the blind field, (iii) extrastriate pathways unaffected by the damage, and (iv) downstream, higher-level neuronal networks. However, residual structures have a triple handicap to be fully functional: (i) fewer neurons, (ii) lack of sufficient attentional resources because of the dominant intact hemisphere caused by excitation/inhibition dysbalance, and (iii) disturbance in their temporal processing. Because of this resulting activation loss, residual structures are unable to contribute much to everyday vision, and their "non-use" further impairs synaptic strength. However, residual structures can be reactivated by engaging them in repetitive stimulation by different means: (i) visual experience, (ii) visual training, or (iii) noninvasive electrical brain current stimulation. These methods lead to strengthening of synaptic transmission and synchronization of partially damaged structures (within-systems plasticity) and downstream neuronal networks (network plasticity). Just as in normal perceptual learning, synaptic plasticity can improve vision and lead to vision restoration. This can be induced at any time after the lesion, at all ages and in all types of visual field impairments after retinal or brain damage (stroke, neurotrauma, glaucoma, amblyopia, age-related macular degeneration). If and to what extent vision restoration can be achieved is a function of the amount of residual tissue and its activation state. However, sustained improvements require repetitive stimulation which, depending on the method, may take days (noninvasive brain stimulation) or months (behavioral training). By becoming again engaged in everyday vision, (re)activation of areas of residual vision outlasts the stimulation period, thus contributing to lasting vision restoration and improvements in quality of life.
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Abstract
The term blindsight describes the non-reflexive visual functions that remain or recover in fields of absolute cortical blindness. As visual stimuli confined to such fields are subjectively invisible, they are customarily announced by visible or audible cues that inform the patients when to respond. The pervasive use of cueing has spawned the widely held assumption that sight and blindsight differ in that only blindsight requires cueing. To test this assumption, we measured detection of auditorily cued and un-cued stimuli in three hemianopic patients. Stimuli fell onto the photosensitive retina of the subjectively blind field, onto the objectively blind optic disc, and, in one patient, into a region where they evoked impoverished conscious sight. Regardless of whether cues were given, performance was highly significant in the latter region of poor sight, clearly above chance in the subjectively blind field, and random in the optic disc control condition. Moreover, cues enhanced detection only in the relatively blind field. Showing that blindsight performance persists when cues are omitted, the results imply that non-reflexive responses can be initiated in the absence of both stimulus awareness and perceptible cues.
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Affiliation(s)
- Petra Stoerig
- Institute of Experimental Psychology, Heinrich-Heine-University Dusseldorf Dusseldorf, Germany
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15
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Combined functional MRI and diffusion tensor imaging analysis of visual motion pathways. J Neuroophthalmol 2009; 29:96-103. [PMID: 19491631 DOI: 10.1097/wno.0b013e3181a58ef8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Motion perception may be preserved after damage to striate cortex (primary visual cortex, area V1). Awareness and normal discrimination of fast-moving stimuli have been observed even in the complete absence of V1. These facts suggest that motion-sensitive cortex (the V5/MT complex or V5/MT+) may be activated by direct thalamic or collicular inputs that bypass V1. Such projections have been identified previously in monkeys but have not been shown in humans using neuroimaging techniques. METHODS We used diffusion tensor imaging (DTI) tractography to visualize white matter fiber tracts connecting with V5/MT+ in 10 healthy volunteers. V5/MT+ was localized for each subject using functional MRI (fMRI). Functional activity maps were overlaid on high-resolution anatomical images and registered with the diffusion-weighted images to define V5/MT+ as the region of interest (ROI) for DTI tractography analysis. Fibers connecting to V1 were excluded from the analysis. RESULTS Using conservative tractography parameters, we found connections between the V5/MT+ region and the posterior thalamus and/or superior colliculus in 4 of 10 subjects. CONCLUSIONS Connections between the V5/MT+ region and the posterior thalamus and/or superior colliculus may explain visual motion awareness in the absence of a functioning V1.
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Schmalzl L, Palermo R, Harris IM, Coltheart M. Face inversion superiority in a case of prosopagnosia following congenital brain abnormalities: What can it tell us about the specificity and origin of face-processing mechanisms? Cogn Neuropsychol 2009; 26:286-306. [DOI: 10.1080/02643290903086904] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Van der Stigchel S, van Zoest W, Theeuwes J, Barton JJS. The Influence of “Blind” Distractors on Eye Movement Trajectories in Visual Hemifield Defects. J Cogn Neurosci 2008; 20:2025-36. [PMID: 18416675 DOI: 10.1162/jocn.2008.20145] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
There is evidence that some visual information in blind regions may still be processed in patients with hemifield defects after cerebral lesions (“blindsight”). We tested the hypothesis that, in the absence of retinogeniculostriate processing, residual retinotectal processing may still be detected as modifications of saccades to seen targets by irrelevant distractors in the blind hemifield. Six patients were presented with distractors in the blind and intact portions of their visual field and participants were instructed to make eye movements to targets in the intact field. Eye movements were recorded to determine if blind-field distractors caused deviation in saccadic trajectories. No deviation was found in one patient with an optic chiasm lesion, which affect both retinotectal and retinogeniculostriate pathways. In five patients with lesions of the optic radiations or the striate cortex, the results were mixed, with two of the five patients showing significant deviations of saccadic trajectory away from the “blind” distractor. In a second experiment, two of the five patients were tested with the target and the distractor more closely aligned. Both patients showed a “global effect,” in that saccades deviated toward the distractor, but the effect was stronger in the patient who also showed significant trajectory deviation in the first experiment. Although our study confirms that distractor effects on saccadic trajectory can occur in patients with damage to the retinogeniculostriate visual pathway but preserved retinotectal projections, there remain questions regarding what additional factors are required for these effects to manifest themselves in a given patient.
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Affiliation(s)
| | - Wieske van Zoest
- 1Vrije Universiteit, Amsterdam, the Netherlands
- 2University of British Columbia, Vancouver, BC, Canada
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Wong P, Kaas JH. Architectonic subdivisions of neocortex in the gray squirrel (Sciurus carolinensis). Anat Rec (Hoboken) 2008; 291:1301-33. [PMID: 18780299 PMCID: PMC2908424 DOI: 10.1002/ar.20758] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Squirrels are highly visual mammals with an expanded cortical visual system and a number of well-differentiated architectonic fields. To describe and delimit cortical fields, subdivisions of cortex were reconstructed from serial brain sections cut in the coronal, sagittal, or horizontal planes. Architectonic characteristics of cortical areas were visualized after brain sections were processed with immunohistochemical and histochemical procedures for revealing parvalbumin, calbindin, neurofilament protein, vesicle glutamate transporter 2, limbic-associated membrane protein, synaptic zinc, cytochrome oxidase, myelin or Nissl substance. In general, these different procedures revealed similar boundaries between areas, suggesting that functionally relevant borders were being detected. The results allowed a more precise demarcation of previously identified areas as well as the identification of areas that had not been previously described. Primary sensory cortical areas were characterized by sparse zinc staining of layer 4, as thalamocortical terminations lack zinc, as well as by layer 4 terminations rich in parvalbumin and vesicle glutamate transporter 2. Primary areas also expressed higher levels of cytochrome oxidase and myelin. Primary motor cortex was associated with large SMI-32 labeled pyramidal cells in layers 3 and 5. Our proposed organization of cortex in gray squirrels includes both similarities and differences to the proposed of cortex in other rodents such as mice and rats. The presence of a number of well-differentiated cortical areas in squirrels may serve as a guide to the identification of homologous fields in other rodents, as well as a useful guide in further studies of cortical organization and function.
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Affiliation(s)
- Peiyan Wong
- Department of Psychology, Vanderbilt University, Nashville TN 37212
| | - Jon H. Kaas
- Department of Psychology, Vanderbilt University, Nashville TN 37212
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Gautschi M, Clarke PGH. Neuronal death in the lateral geniculate nucleus of young ferrets following a cortical lesion: time-course, age dependence and involvement of caspases. Brain Res 2007; 1167:20-30. [PMID: 17678880 DOI: 10.1016/j.brainres.2007.05.063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Accepted: 05/31/2007] [Indexed: 10/23/2022]
Abstract
In humans and many other mammalian species, the behavioural consequences of a cortical lesion tend to be milder when it occurs early in life, and there is evidence that an important factor contributing to the behavioural sparing in the young is the formation of new thalamo-cortical connections by thalamic neurons initially connected with the lesioned area. However, this plasticity may be hindered by the secondary death of many of these neurons owing to the elimination by the primary lesion of their trophic support from the cortex. With the long-term aim of preventing this neuronal death, we have here characterised its timing in the lateral geniculate nucleus of ferrets following lesions of the visual cortex on postnatal days 5, 10, 20 or 35. After the earliest lesions (P5 or P10), this cell death began rapidly and occurred synchronously, being maximal at 48 h and declining to zero over the next few days. Following later lesions the cell death began more slowly and continued for longer. The dying neurons contained activated caspase-3 and fragmented DNA and their number 2 days after a P5 lesion was reduced by the broad-band caspase inhibitor z-VAD.fmk. These experiments open the way for a concerted effort to enhance adaptive plasticity by neuroprotection in the hours or days following a cortical lesion.
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Affiliation(s)
- Matthias Gautschi
- Département de Biologie Cellulaire et de Morphologie (DBCM), Université de Lausanne, Rue du Bugnon 9, CH-1005 Lausanne, Switzerland
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Stoerig P. Blindsight, conscious vision, and the role of primary visual cortex. PROGRESS IN BRAIN RESEARCH 2007; 155:217-34. [PMID: 17027389 DOI: 10.1016/s0079-6123(06)55012-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
What is the role the primary visual cortex (V1) in vision? Is it necessary for conscious sight, as indicated by the cortical blindness that results from V1 destruction? Is it even necessary for blindsight, the nonreflexive visual functions that can be evoked with stimuli presented to cortically blind fields? In the context of this controversial issue, I present evidence indicating that not only is blindsight possible, but that conscious vision may, to a varying degree, return to formerly blind fields with time and practice even in cases where functional neuroimaging reveals no V1 activation.
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Affiliation(s)
- Petra Stoerig
- Institute of Experimental Psychology II, Heinrich-Heine-University Düsseldorf, 40225 Düsseldorf, Germany.
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21
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Amicuzi I, Stortini M, Petrarca M, Di Giulio P, Di Rosa G, Fariello G, Longo D, Cannatà V, Genovese E, Castelli E. Visual recognition and visually guided action after early bilateral lesion of occipital cortex: a behavioral study of a 4.6-year-old girl. Neurocase 2006; 12:263-79. [PMID: 17190747 DOI: 10.1080/13554790601026106] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We report the case of a 4.6-year-old girl born pre-term with early bilateral occipital damage. It was revealed that the child had non-severely impaired basic visual abilities and ocular motility, a selective perceptual deficit of figure-ground segregation, impaired visual recognition and abnormal navigating through space. Even if the child's visual functioning was not optimal, this was the expression of adaptive anatomic and functional brain modifications that occurred following the early lesion. Anatomic brain structure was studied with anatomic MRI and Diffusor Tensor Imaging (DTI)-MRI. This behavioral study may provide an important contribution to understanding the impact of an early lesion of the visual system on the development of visual functions and on the immature brain's potential for reorganisation related to when the damage occurred.
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Affiliation(s)
- Ileana Amicuzi
- Pediatric Rehabilitation Department, Children's Hospital Bambino Gesù, Rome, Italy.
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22
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Boire D, Matteau I, Casanova C, Ptito M. Retinal projections to the lateral posterior-pulvinar complex in intact and early visual cortex lesioned cats. Exp Brain Res 2004; 159:185-96. [PMID: 15252699 DOI: 10.1007/s00221-004-1946-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2004] [Accepted: 04/18/2004] [Indexed: 11/25/2022]
Abstract
In intact cats, it is generally considered that the lateral posterior-pulvinar complex (LP-pulvinar) does not receive direct retinal terminals, with the exception of the retino-recipient zone known as the geniculate wing. There is, however, some evidence that early lesions of the visual cortex can occasionally induce the formation of novel retinal projections to the LP nucleus. Given the importance of knowing the connectivity pattern of the LP-pulvinar complex in intact and lesioned animals, we used the B fragment of cholera toxin, a sensitive anterograde tracer, to reinvestigate the retinal projections to the LP-pulvinar in normal cats and in cats with early unilateral lesions of the visual cortex (areas 17 and 18). Immunohistochemical localization of the toxin was performed to show the distribution and morphology of retinofugal terminals. A direct bilateral but predominantly contralateral retinal projection reached the caudal portion of LPl and LPm in the form of patches located mainly along its dorsomedial surface and many scattered terminals. The distribution of retinal projections to LP-pulvinar in intact and operated cats did not differ. Contrary to what had been previously reported, we found no evidence for lesion-induced sprouting of retinal axons in these higher-order thalamic nuclei. Retinal input to the LP-pulvinar might modulate visual responses driven by primary visual cortex or superior colliculus.
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Affiliation(s)
- Denis Boire
- Ecole d'Optométrie, Université de Montréal, CP 6128 Succ Centre-Ville, H3C 3J7, Montréal, Canada.
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23
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Payne BR, Cornwell P. Greater sparing of visually guided orienting behavior after early unilateral occipital lesions: insights from a comparison with the impact of bilateral lesions. Behav Brain Res 2004; 150:109-16. [PMID: 15033284 DOI: 10.1016/j.bbr.2003.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2003] [Revised: 07/01/2003] [Accepted: 07/01/2003] [Indexed: 10/27/2022]
Abstract
We know that cats with bilateral lesions of occipital visual cortical areas 17, 18 and 19 sustained during the first postnatal week exhibit a modest level of sparing of the ability to re-orient head and eyes to new stimuli relative to cats that incurred equivalent lesions in adulthood. We now report that cats with equivalent unilateral lesions sustained during the first postnatal week (P1-4), or at the end of the first postnatal month (P27-30), orient to stimuli presented in the contralesional field as proficiently as to stimuli introduced into the ipsilesional field. Moreover, levels of proficiency are indistinguishable from those exhibited by intact cats. Thus, the sparing is greater following unilateral lesions than following bilateral lesions, and the level of sparing approaches completeness. The difference between the bilateral and unilateral lesion results suggests types of pathway reorganizations that may emerge as a result of unilateral occipital lesions. We postulate that the greater sparing is based on modifications in both excitatory and inhibitory circuitry linked to the intact hemisphere, and we provide a framework for future investigations that should be relevant to the comprehension of the repercussions of early unilateral and bilateral lesions sustained by monkeys and humans, which also show more robust residual vision following early relative to later damage of occipital cortex.
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Affiliation(s)
- Bertram R Payne
- Department of Anatomy and Neurobiology, Center for Advanced Biomedical Research, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
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24
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Gross CG, Moore T, Rodman HR. Visually guided behavior after V1 lesions in young and adult monkeys and its relation to blindsight in humans. PROGRESS IN BRAIN RESEARCH 2004; 144:279-94. [PMID: 14650855 DOI: 10.1016/s0079-6123(03)14419-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
After lesions of striate cortex in primates, there is still the capacity to detect and localize visual stimuli. In this chapter we review three aspects of our study of this phenomenon in macaques. First, we found that macaques that received their striate lesions as infants had considerably greater ability to detect and localize stimuli than those that received similar lesions as adults. Second, we suggest that the visual functions that survive striate lesions in macaques made in adulthood resemble those in human 'blindsight'. Third, we report that monkeys with striate lesions made in infancy are able to discriminate direction of visual motion.
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Affiliation(s)
- Charles G Gross
- Department of Psychology, Green Hall, Princeton University, Princeton, NJ 08544, USA.
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25
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Abstract
When visual stimuli are presented in the cortically blind visual field of patients or monkeys with verified destruction of striate cortex, many subjects can voluntarily respond to them. In studies of this blindsight, the on- and/or offset of the visual stimulus is usually known to the subject, either because it is signaled in some way or because the subject can present the stimulus himself. To study the effect of stimulus uncertainty on the responses of four hemianopic monkeys and one human hemianope, we compared trials on which the subjects themselves could instantly trigger the stimulus with trials on which the same stimulus appeared 1-7 s after the start-light that normally served as the trigger was first touched. The latter manipulation diminished both the percentage of trials on which the subjects responded and the percentage correct when they did respond. As the start-light disappeared when touched in the first but not second condition, we interpret our results as indicating an influential role for attention in blindsight. Although keeping attention focused on the start-light and delaying the target impaired performance especially in the monkeys, localization was still significant in three and hardly affected in GY.
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Affiliation(s)
- Alan Cowey
- Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.
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26
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Payne BR, Rushmore RJ. Functional circuitry underlying natural and interventional cancellation of visual neglect. Exp Brain Res 2003; 154:127-53. [PMID: 14625667 DOI: 10.1007/s00221-003-1660-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2003] [Accepted: 07/28/2003] [Indexed: 10/26/2022]
Abstract
A large body of work demonstrates that lesions at multiple levels of the visual system induce neglect of stimuli in the contralesional visual field and that the neglect dissipates as neural compensations naturally emerge. Other studies show that interventional manipulations of cerebral cortex, superior colliculus or deep-lying midbrain structures have the power to attenuate, or cancel, the neglect and reinstate orienting into a neglected hemifield, and even into a profound cortically blind field. These results, and those derived from experiments on the behavioral impacts of unilateral and bilateral lesions, lead us to evaluate the repercussions of unilateral and bilateral deactivations, neural compensations and cancellations of attentional deficits in terms of an overarching hypothesis of neglect. The cancellations can be both striking and enduring, and they suggest that therapeutic strategies can be developed to reverse or ameliorate neglect in human patients. Animal studies show that in many instances of neglect adequate representations and the accompanying motor mechanisms are present despite the lesion and they simply need to be unmasked and brought into use to effect a remedy.
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Affiliation(s)
- Bertram R Payne
- Cerebral Dynamics, Department of Anatomy and Neurobiology, Boston University School of Medicine, W702, Boston, MA 02118, USA.
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27
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Giaschi D, Jan JE, Bjornson B, Young SA, Tata M, Lyons CJ, Good WV, Wong PKH. Conscious visual abilities in a patient with early bilateral occipital damage. Dev Med Child Neurol 2003; 45:772-81. [PMID: 14580134 DOI: 10.1111/j.1469-8749.2003.tb00888.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/26/2024]
Abstract
A 21-year-old male presented with occipital lobes that were extensively damaged by bilateral infarcts present at birth. The absence of the striate cortex was confirmed with anatomic and functional MRI and high-resolution EEG. His cortical visual impairment was severe, but he retained a remarkable ability to see fast-moving stimuli. Horizontal optokinetic nystagmus could be elicited from either eye. Resolution acuity was close to normal providing the patient was allowed to move his head and eyes. The direction of motion in random-dot patterns could be discriminated with perfect accuracy at speeds above 2 deg/s, and the patient reported that he could 'see' the motion at fast but not at slow speeds. This conscious residual vision for motion is known as Riddoch's phenomenon, but it has never been reported in the complete absence of the striate cortex. Functional neuroimaging revealed activation that was outside the motion-responsive regions of the extrastriate cortex. This case demonstrates remarkable plasticity in the human visual system and may have implications for understanding the functional organization of the motion pathways.
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Affiliation(s)
- Deborah Giaschi
- Department of Ophthalmology, University of British Columbia (UBC), Vancouver, Canada.
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28
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Trevethan CT, Sahraie A. Spatial and temporal processing in a subject with cortical blindness following occipital surgery. Neuropsychologia 2003; 41:1296-306. [PMID: 12757903 DOI: 10.1016/s0028-3932(03)00049-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Blindsight subjects are typically better at discriminating rapid, transient visual events than those with gradual on/off-sets. Surprisingly, the detailed investigation of temporal characteristics of mechanisms mediating blindsight is only reported in one subject (GY). It is of interest to establish whether these characteristics are similar to those in other cases of blindsight. Here, we report on a systematic study of spatio-temporal properties of mechanisms mediating blindsight in a subject VN. VN has a lower right quadranopia following surgical removal of the left occipital cortex above the calcarine sulcus, therefore, there are no remaining islands of intact visual cortex within this area. Similar to GY, the blindsight mechanisms in VN have narrowly tuned band-pass temporal characteristics with a peak sensitivity at 20Hz and above chance performance at temporal frequencies >/=10 and </=33Hz. The spatial channel in VN has low-pass characteristics with an upper cut-off <3.5c/ degrees. There is extensive spatial summation in the blindfield whereas no temporal summation was found in the time range tested (50-1600ms). In agreement with our previous reports, pupillary responses can predict the existence of residual vision within the field defect and show similar spatial characteristics to those obtained psychophysically. The spatio-temporal characteristics of blindsight in VN reported here are similar to those reported in subjects with ischaemic lesions, suggesting that such visual capacities need not necessarily be attributed to spared areas of visual cortex.
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Affiliation(s)
- Ceri T Trevethan
- Vision Research Laboratories, Department of Psychology, King's College, University of Aberdeen, AB24 2UB, Aberdeen, UK
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29
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Payne BR. Limit of spared pattern vision following lesions of the immature visual cortex. Exp Brain Res 2003; 150:61-7. [PMID: 12698217 DOI: 10.1007/s00221-003-1387-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2002] [Accepted: 12/19/2002] [Indexed: 12/24/2022]
Abstract
Lesions of primary visual cortex sustained early in life spare certain aspects of visual processing that can be linked to expansions of bypass pathways to extrastriate cortex. They also trigger, in an age-dependent way, partial or complete transneuronal retrograde degeneration of beta (X) retinal ganglion cells, which are implicated in visual processing under conditions of low contrast. We used two-dimensional geometric patterns whose saliency was reduced by gradually increasing levels of superimposed masking lines, and by reductions in spatial contrast. Normative data were collected from intact cats, and baseline lesion data were collected from cats with lesions sustained as young adults (postnatal day 180, P180). Experimental data were collected from cats that sustained lesions on P1-3 or P26-30. For high contrast patterns, the adult group was impaired at both acquisition (sequential progressive levels of masking) and concurrent (parallel high and low levels of masking) performance, whereas the early-lesioned groups were impaired only at concurrent performance. All lesion groups were equally impaired when contrast was reduced to modest or lower levels. These results show that sparing of masked-pattern learning is limited to the high end of the spatial contrast domain.
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Affiliation(s)
- Bertram R Payne
- Department of Anatomy and Neurobiology, Center for Advanced Biomedical Research, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
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30
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Abstract
Monkey data suggest that of all perceptual abilities, motion perception is the most likely to survive striate damage. The results of studies on motion blindsight in humans, though, are mixed. We used an indirect strategy to examine how responses to visible stimuli were modulated by blind-field stimuli. In a 26-year-old man with focal striate lesions, discrimination of visible optic flow was enhanced about 7% by blind-field flow, even though discrimination of optic flow in the blind field alone (the direct strategy) was at chance. Pursuit of an imagined target using peripheral cues showed reduced variance but not increased gain with blind-field cues. Preceding blind-field prompts shortened reaction times to visible targets by about 10 msec, but there was no attentional crowding of visible stimuli by blind-field distractors. A similar efficacy of indirect blind-field optic flow modulation was found in a second patient with residual vision after focal striate damage, but not in a third with more extensive medial occipito-temporal damage. We conclude that indirect modulatory strategies are more effective than direct forced-choice methods at revealing residual motion perception after focal striate lesions.
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31
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Payne BR, Lomber SG. Plasticity of the visual cortex after injury: what's different about the young brain? Neuroscientist 2002; 8:174-85. [PMID: 11954561 DOI: 10.1177/107385840200800212] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The repercussions of localized injury of the cerebral cortex in young brains differ from the repercussions triggered by equivalent damage of the mature brain. In the young brain, some distant neurons are more vulnerable to the lesion, whereas others survive and expand their projections to bypass damaged and degenerated structures. The net result is sparing of neural processing and behaviors. This article summarizes both the modifications in visual pathways resulting from visual cortex lesions sustained early in life and the neural and behavioral processes that are spared or permanently impaired. Experiments using reversible deactivation show that at least two highly localizable functions of normal cerebral cortex are remapped across the cortical surface as a result of an early lesion of the primary visual cortex. Moreover, the redistributions have spread the essential neural operations underlying orienting behavior from the visual parietal cortex to a normally functionally distinct type of cortex in the visual temporal system, and in the opposite direction for complex-pattern recognition. Similar functional reorganizations may underlie sparing of neural processes and behavior following early lesions in other cerebral systems, and these other systems may respond well to emerging therapeutic strategies designed to enhance the sparing of functions.
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Affiliation(s)
- Bertram R Payne
- Laboratory for Visual Perception and Cognition, Department of Anatomy and Neurobiology, Boston University School of Medicine, Massachusetts 02118, USA.
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32
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Boire D, Théoret H, Ptito M. Visual pathways following cerebral hemispherectomy. PROGRESS IN BRAIN RESEARCH 2002; 134:379-97. [PMID: 11702556 DOI: 10.1016/s0079-6123(01)34025-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The anatomical consequences of unilateral cerebral hemispherectomy in some animal models are reviewed. We have shown that the retinogenigulate pathway undergoes severe degenerative changes in hemispherectomized monkeys, greater than those shown in cats and we proposed that remaining retinal terminals to the dorsal lateral geniculate nucleus have little potential for conveying visual information any further. All subdivisions of the pulvinar undergo severe degeneration following hemispherectomy showing that the ascending tectofugal pathway is also shut off. On the other hand, the retina subserving the blind field is not depleted of ganglion cells which still send normal appearing terminals to the midbrain pretectum and superior colliculus. Visual information from the blind hemifield can thus gain access to the brain and could potentially reach the contralateral cerebral cortex through the midbrain commissure and possibly through thalamic commissural cells.
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Affiliation(s)
- D Boire
- Ecole d'Optométrie, Université de Montréal, CP, 6128, succursale Centre-ville, Montréal, PQ, H3C 3J7 Canada
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33
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Desautels A, Casanova C. Response properties in the pulvinar complex after neonatal ablation of the primary visual cortex. PROGRESS IN BRAIN RESEARCH 2002; 134:83-95. [PMID: 11702565 DOI: 10.1016/s0079-6123(01)34007-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Injuries to specific areas of the brain (such as cerebrovascular accidents or surgical procedures) and particularly to the primary visual cortex, yield profound visual defects. The level of spared visual functions or residual vision depends on the extent and location of the lesion as well as the age at which the trauma occurs. For instance, in primate as well as non-primate species, it is well established that lesions in adulthood have a more profound effect than those occurring in young animals. The recovery of visually guided behavior observed after massive destruction of the occipital cortex in young animals across many species has been generally associated with the reorganization of the pathways from the extrageniculate thalamus to the spared visual cortex, i.e. the extrastriate areas. In this chapter, we present some evidence that the lateral posterior-pulvinar (LP-pulvinar) complex may contribute to maintaining visual capacities in brain-damaged cats. Our data indicate that the overall visual responsiveness of the lateral part of the LP (LPl) cells is not altered by the early removal of the visual cortex. However, some specific properties differ from those of intact animals: on average, LPl neurons in brain-damaged animals are more broadly tuned for orientation than that in intact cats. Spatial frequency tuning functions are also affected since most units in lesioned animals are of the low-pass type. Moreover, most LPl cells of lesioned cats responded to drifting gratings with modulated discharges and a linear spatial summation within their receptive field, a characteristic that is infrequently observed in intact animals. The change in LPl response properties observed in the present study is likely to come from the reorganization of cortical and retinal fibers reaching this extrageniculate nucleus.
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Affiliation(s)
- A Desautels
- Laboratoire des Neurosciences de la Vision, Ecole d'Optométrie, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, PQ, H3C 3J7 Canada
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34
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Payne BR, Lomber SG. Reconstructing functional systems after lesions of cerebral cortex. Nat Rev Neurosci 2001; 2:911-9. [PMID: 11733798 DOI: 10.1038/35104085] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- B R Payne
- Laboratory for Visual Perception and Cognition, Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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35
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Stiers P, van den Hout BM, Haers M, Vanderkelen R, de Vries LS, van Nieuwenhuizen O, Vandenbussche E. The variety of visual perceptual impairments in pre-school children with perinatal brain damage. Brain Dev 2001; 23:333-48. [PMID: 11504606 DOI: 10.1016/s0387-7604(01)00241-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To study the selectivity of visual perceptual impairment in children with early brain injury, eight visual perceptual tasks (L94), were administered to congenitally disabled children both with and without risk for cerebral visual impairment (CVI). The battery comprised six object-recognition and two visuoconstructive tasks. Seven tasks were newly designed. For these normative data are presented (age 2.75-6.50 years). Because the recognition tasks required object naming, each item included a canonical control drawing and visual perceptual ability was evaluated relative to the non-verbal intelligence level, instead of chronological age. In 22 multiple disabled children with no indications of CVI, the frequency of impairment did not exceed that in the reference sample for any L94 task. In contrast, in 57 5-year-old children who were at risk for CVI due to pre-maturity or birth asphyxia, a significant increase in the frequency of impairment was seen on six L94 tasks (range 12-38%). However, only five children had more than two impairments, indicating that the deficits were selective, not pervasive. We conclude that early brain lesions interfere with the functioning of particular visual subsystems, yet leave other subsystems intact and functioning within the normal range.
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Affiliation(s)
- P Stiers
- Laboratorium voor Neuropsychologie, K.U. Leuven, Campus Gasthuisberg, Herestraat 49, B-3000, Leuven, Belgium.
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36
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Rodman HR, Sorenson KM, Shim AJ, Hexter DP. Calbindin immunoreactivity in the geniculo-extrastriate system of the macaque: implications for heterogeneity in the koniocellular pathway and recovery from cortical damage. J Comp Neurol 2001; 431:168-81. [PMID: 11169998 DOI: 10.1002/1096-9861(20010305)431:2<168::aid-cne1063>3.0.co;2-n] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although most projection neurons in the primate dorsal lateral geniculate nucleus (dLGN) target striate cortex (V1), a small number project instead to extrastriate visual areas and have been suggested to play a role in the preserved vision ("blindsight") that survives damage to V1. Moreover, the distribution of dLGN cells projecting to extrastriate bears a striking similarity to that of neurons that stain for calbindin D-28K (Cal), a calcium-binding protein involved in regulating neuronal excitability and considered a marker for the koniocellular or "K" pathway of geniculocortical processing. In these studies, we used double-labeling techniques to examine whether Cal content characterizes all or a subset of neurons making up the geniculo-extrastriate pathway in normal macaque monkeys. After injections of cholera toxin B-subunit into the prelunate gyrus, the proportion of retrogradely labeled neurons in the dLGN that were also immunoreactive for Cal varied from less than 40% to over 80%, indicating that only a subset of the geniculo-extrastriate projection falls within the K pathway as defined by Cal content. Analysis of the injected territories indicated that identity of the extrastriate cortical target may be systematically related to Cal content in the geniculo-extrastriate projection. To see whether the Cal-immunoreactive dLGN population might potentially play a role in preserved vision after V1 damage, we also examined the dLGN of a macaque that had sustained a lesion of V1 in infancy and survived until 4 years. In this animal, large, intensely Cal-immunoreactive neurons were found scattered throughout the otherwise degenerated dLGN zones and made up over 95% of the identifiable remaining neurons. The results support an emerging view that the macaque koniocellular system is highly heterogeneous in nature and also suggest that Cal content may be a critical feature of the pathway by which visual information reaches extrastriate cortex in the absence of V1.
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Affiliation(s)
- H R Rodman
- Department of Psychology, Emory University, 532 Kilgo Circle, Atlanta, GA 30322, USA.
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37
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Direction of motion discrimination after early lesions of striate cortex (V1) of the macaque monkey. Proc Natl Acad Sci U S A 2001. [PMID: 11134530 PMCID: PMC14589 DOI: 10.1073/pnas.021519698] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previous studies have established that humans and monkeys with damage to striate cortex are able to detect and localize bright targets within the resultant scotoma. Electrophysiological evidence in monkeys suggests that residual vision also might include sensitivity to direction of visual motion. We tested whether macaque monkeys with longstanding lesions of striate cortex (V1), sustained in infancy, could discriminate visual stimuli on the basis of direction of motion. Three monkeys with unilateral striate cortex lesions sustained in infancy were tested 2-5 years postlesion on a direction of motion discrimination task. Each monkey was trained to make saccadic eye movements to a field of moving dots or to withhold such eye movements, depending on the direction of motion in a coherent random dot display. With smaller motion displays, monkeys were unable to detect or discriminate motion within the scotoma, although they could discriminate moving from static stimuli. Yet, each monkey was able to discriminate direction of motion when the motion stimulus was larger, but still confined to the scotoma. The results demonstrate that the recovery after infant damage to striate cortex includes some sensitivity to direction of visual motion.
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38
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Moore T, Rodman HR, Gross CG. Direction of motion discrimination after early lesions of striate cortex (V1) of the macaque monkey. Proc Natl Acad Sci U S A 2001; 98:325-30. [PMID: 11134530 PMCID: PMC14589 DOI: 10.1073/pnas.98.1.325] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Previous studies have established that humans and monkeys with damage to striate cortex are able to detect and localize bright targets within the resultant scotoma. Electrophysiological evidence in monkeys suggests that residual vision also might include sensitivity to direction of visual motion. We tested whether macaque monkeys with longstanding lesions of striate cortex (V1), sustained in infancy, could discriminate visual stimuli on the basis of direction of motion. Three monkeys with unilateral striate cortex lesions sustained in infancy were tested 2-5 years postlesion on a direction of motion discrimination task. Each monkey was trained to make saccadic eye movements to a field of moving dots or to withhold such eye movements, depending on the direction of motion in a coherent random dot display. With smaller motion displays, monkeys were unable to detect or discriminate motion within the scotoma, although they could discriminate moving from static stimuli. Yet, each monkey was able to discriminate direction of motion when the motion stimulus was larger, but still confined to the scotoma. The results demonstrate that the recovery after infant damage to striate cortex includes some sensitivity to direction of visual motion.
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Affiliation(s)
- T Moore
- Department of Psychology, Green Hall, Princeton University, Princeton, NJ 08544-1010, USA.
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39
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Payne BR, Lomber SG, Gelston CD. Graded sparing of visually-guided orienting following primary visual cortex ablations within the first postnatal month. Behav Brain Res 2000; 117:1-11. [PMID: 11099752 DOI: 10.1016/s0166-4328(00)00276-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We compared the abilities of intact cats and cats that incurred lesions of areas 17 and 18 in adulthood, at one month of age (P28), or on the day of birth (P1), to detect and orient towards visual stimuli either moved into or illuminated in the periphery of the visual field, and to detect and orient towards a stationary, broad-band white-noise auditory stimulus. For all groups of cats, movement of a stimulus into the visual field was a more potent stimulus for evoking visually-guided orienting movements than illumination of a static light-emitting diode (LED). The potency of the auditory stimulus was also extremely high. Proficiency on both visual tasks was graded according to the age at which areas 17 and 18 were ablated in the sequence: adult, P1, P28 and intact in the sequence worst-->best performance. The superior performance of the P1- and P28-groups provided evidence for sparing of visually-guided orienting, but the sparing was incomplete because it did not match performance of intact cats. Lesions of areas 17 and 18 incurred in adulthood had no significant impact on orienting to auditory white-noise stimuli. However, orienting performance to auditory stimuli presented in the peripheral quadrants was slightly superior in the P28 group and reduced in the P1 group. Thus, the visual sparing exhibited by the P1 group may be at the expense of highly proficient orienting to auditory cues. Overall, these results extend our knowledge by showing that in addition to P1-cats, cats that incur lesions of areas 17 and 18 at one month-of-age also exhibit sparing of visually-guided orienting, and that the sparing is not confined to a single stimulation paradigm. Finally, the covariation in the magnitude of pathway modifications with the scale of the orienting proficiency in P1- and P28 cats helps to solidify the linkage between rewired brain pathways and spared visually-guided behaviors.
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Affiliation(s)
- B R Payne
- Department of Anatomy and Neurobiology, Center for Advanced Biomedical Research, Boston University School of Medicine, Boston, MA, 02118, USA.
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Villablanca JR, Hovda DA. Developmental neuroplasticity in a model of cerebral hemispherectomy and stroke. Neuroscience 2000; 95:625-37. [PMID: 10670431 DOI: 10.1016/s0306-4522(99)00482-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cerebral hemispherectomy, a last resort treatment for childhood epilepsy, is a standard procedure which dramatically illustrates the resilience of the brain to extensive damage. If this operation, also mimicking long-term, extensive unilateral capsular stroke, is performed in postnatal cats of up to 60 days of age, there is a remarkable recovery/sparing of neurological functions that is not seen when the lesion occurs during late fetal life or in adulthood. A long-term effect at all ages is loss of neurons in bilateral brain areas remote from the resection site. This is pronounced in adult cats and shows intriguing, paradoxical features in fetal animals, but is substantially attenuated in neonatal cats. Similarly, large-scale reinnervation of subcortical sites (sprouting) by neurons of the remaining, intact hemisphere is prominent in young cats, but not in fetal or adult animals. These and other restorative processes (described herein) in young postnatal animals are matched by relatively higher rates of local cerebral glucose utilization, supporting the notion that they underlie the improved behavioral outcome. Thus, during a critical, defined stage of maturation, presumably common to higher mammals including humans, the brain entirely remodels itself in response to extensive but focal injury. Perhaps the molecular environment allowing for rescue of neurons and enhanced reinnervation at a specific developmental stage could be recreated in subjects with brain lesions at less favorable ages, thereby helping to restore circuitry and spare neurons. However, replacement via transplantation of neurons eliminated by the damage appears to be crucial in attempts to further preserve cells located remotely but yet destined to die or decrease in size. This article presents abundant evidence to show that there is a surprisingly comprehensive long-term morphological remodeling of the entire brain after extensive unilateral damage and that this occurs preferentially during a discrete period of early life. Additional evidence strongly suggests that the remodeling underlies the outstanding behavioral and functional recovery/sparing following early cerebral hemispherectomy. We argue that this period of reduced brain vulnerability to injury also exists in other higher mammals, including man, and suggest ways to enhance restorative processes after stroke/hemispherectomy occurring at other ages.
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Affiliation(s)
- J R Villablanca
- Department of Psychiatry and Biobehavioral Sciences, Mental Retardation Research Center and Brain Research Institute, University of California, Los Angeles, CA 90024-1759, USA.
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Abstract
It is well known that a lesion in the optic radiation or striate cortex leads to blind visual regions in the retinotopically corresponding portion of the visual field. However, various studies show that some subjects still perceive certain stimuli even when presented in the "blind" visual field. Such subjects either perceive stimuli abnormally or only certain aspects of them (residual vision) or, in some cases, deny perception altogether even though visual performance can be shown to be above chance (blindsight). Research on monkeys has suggested a variety of parallel extrastriate visual pathways that could bypass the striate cortex and mediate residual vision or blindsight. In the present study, we investigated a subject with perimetrically blind visual areas caused by bilateral brain damage. Black and white stimuli were presented at many locations in the intact and affected areas of the visual field. The subject's task was to state, using confidence levels, whether the target stimulus was black or white. The results revealed an area in the "blind" visual field in which the subject perceived a light flash when the experimental black stimulus was presented. We hypothesize that a spared region in the visual cortex most likely accounts for these findings.
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Affiliation(s)
- H Schärli
- University of Western Australia, Australia
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Scharli H, Harman AM, Hogben JH. Blindsight in subjects with homonymous visual field defects. J Cogn Neurosci 1999; 11:52-66. [PMID: 9950714 DOI: 10.1162/089892999563247] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Brain damage in the visual system can lead to apparently blind visual areas. However, more elaborate testing indicates that some visual ability may still exist for specific stimuli in the otherwise blind regions. This phenomenon is called 'blindsight' if subjects report no conscious awareness of visual stimuli but when forced to guess, nevertheless perform better than chance. It has mainly been suggested that secondary visual pathways are responsible for this phenomenon. However, no published study has clearly shown the neural mechanism responsible for blindsight. Furthermore, experimental artifacts may have been responsible for the appearance of the phenomenon in some subjects. In the present study, the visual fields of nine subjects were mapped and residual visual performance was examined in many areas using three different experimental procedures. Artifacts such as stray light or eye movements were well controlled. In addition, confidence ratings were required after each trial in the forced-choice tests. The results show that only one subject with a lesion in the optic radiation had blindsight in two discrete areas of the affected visual field. Spared optic radiation fibers of the main (primary) geniculo-striate visual pathway were most likely to account for this finding.
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Affiliation(s)
- H Scharli
- Department of Psychology, University of Western Australia, Nedlands 6907, Australia
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Benson PJ, Guo K, Blakemore C. Direction discrimination of moving gratings and plaids and coherence in dot displays without primary visual cortex (V1). Eur J Neurosci 1998; 10:3767-72. [PMID: 9875355 DOI: 10.1046/j.1460-9568.1998.00383.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We present new experimental observations of G.Y., a well-tested patient with unilateral loss of primary visual cortex. We stimulated G.Y.'s blind hemifield using first- and second-order motion stimuli at velocities around psychophysical threshold. Using a dual response paradigm (awareness level of visual motion, motion direction discrimination) psychophysical performance improved with increasing velocity and dot coherence. We were also able to influence directly G.Y.'s performance for the better and at will, by placing the emphasis solely on direction discrimination. In the absence of V1, graduated detection and discrimination of stimuli known to activate both V1 and extrastriate motion areas MT/V5 and MST is still possible. These results are in line with residual visual processing but did not show evidence of unconscious processing of motion stimuli characteristic of 'blindsight'.
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Affiliation(s)
- P J Benson
- University Laboratory of Physiology, Oxford, UK.
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Théoret H, Herbin M, Boire D, Ptito M. Transneuronal retrograde degeneration of retinal ganglion cells following cerebral hemispherectomy in cats. Brain Res 1997; 775:203-8. [PMID: 9439845 DOI: 10.1016/s0006-8993(97)00949-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have assessed the extent of transneuronal retrograde degeneration of retinal ganglion cells (RGCs) following the removal of a whole cerebral hemisphere at postnatal age 16 and 25 days. In the P16 animal, the nasal retina contralateral to the lesion suffered a 41% cell loss, whereas cell loss in the temporal retina ipsilateral to the lesion was 33%. Cell loss was greater in nasal retina and mainly included medium sized cells (200-600 microns2). In the P25 animal overall there was no evidence for ganglion cell loss.
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Affiliation(s)
- H Théoret
- Groupe de Recherche en Neuropsychologie Expérimentale, Université de Montréal, Canada
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Payne BR, Lomber SG. Age dependent modification of cytochrome oxidase activity in the cat dorsal lateral geniculate nucleus following removal of primary visual cortex. Vis Neurosci 1996; 13:805-16. [PMID: 8903025 DOI: 10.1017/s095252380000907x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of the present study was to assess changes in the levels of cytochrome oxidase (CO) activity in the dorsal lateral geniculate nucleus (dLGN) of the adult cat following removal of primary visual cortical areas 17 and 18 on the day of birth (PI), P28, or in adulthood (> or = 6 months). Cytochrome oxidase activity was measured in histological sections 9 or more months after the cortical ablation. Control measures obtained from intact cats show that CO activity is normally highest in the A-laminae of dLGN, and slightly lower in the C-complex. Following visual cortex ablations incurred at any age, CO activity levels are reduced in the A-laminae. This reduction is most profound following ablations incurred on P28 or in adulthood. In contrast, CO activity in the C-complex of dLGN is at nearly normal levels following ablations on P1 or P28, but not in adulthood. These findings contribute to our understanding of the role played by the dLGN in the transfer of visual signals along retino-geniculo-extrastriate pathways that expand following early removal of areas 17 and 18. Moreover, they have implications for our understanding of spared behavioral functions attributed to the extrastriate cortex in cats which incurred early damage of areas 17 and 18.
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Affiliation(s)
- B R Payne
- Department of Anatomy and Neurobiology, Boston University School of Medicine, MA 02118, USA
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