Impairments of Gestalt perception in the intact hemifield of hemianopic patients are reflected in gamma-band EEG activity

Schadow, Jeanette; Dettler, Nicole; Paramei, Galina V.; Lenz, Daniel; Fründ, Ingo; Sabel, Bernhard A.; Herrmann, Christoph S.

doi:10.1016/j.neuropsychologia.2008.10.012

Cited by 43 publications

(50 citation statements)

References 101 publications

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“…To limit the number of variables, units of cardinal orientation preference were preselected as they have been shown to be stronger influenced by callosal input than obliques with whole-field grating stimuli (Schmidt et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

“…It is known that in cats both intrahemispheric and interhemispheric connections extend anisotropically and preferentially link neurons with collinearly aligned RFs (Schmidt et al, 1997b;Rochefort et al, 2009). To examine the interaction between the long-range connectivity within one hemisphere and connections between the two hemispheres, we flanked the single-centered Gabor patches by two collinearly aligned patches of iso-orientation, forming either a vertical line running parallel to the VM or a horizontal line orthogonal to it.…”

Section: A Collinear Context Stabilizes Responses Evoked By Vertical mentioning

confidence: 99%

“…Physiological studies (Payne, 1994;Makarov et al, 2008;Schmidt et al, 2010;Wunderle et al, 2013) support the midline theory that CCs extend the intrinsic network to the other hemisphere to unify the separated visual environments (e.g., Hubel and Wiesel, 1967). Indeed, intrahemispheric and interhemispheric networks have many morphological features in common.…”

Section: Introductionmentioning

confidence: 96%

“…Indeed, intrahemispheric and interhemispheric networks have many morphological features in common. Both long-range intrinsic and callosal axons arborize in a patchy manner (Kisvárday and Eysel, 1992;Houzel et al, 1994) and tend to link collinearly aligned neurons of the same orientation preference (Gilbert and Wiesel, 1989;Kisvárday et al, 1997;Schmidt et al, 1997a;Rochefort et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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An Updated Midline Rule: Visual Callosal Connections Anticipate Shape and Motion in Ongoing Activity across the Hemispheres

et al. 2013

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It is generally thought that callosal connections (CCs) in primary visual cortices serve to unify the visual scenery parted in two at the vertical midline (VM). Here, we present evidence that this applies also to visual features that do not cross yet but might cross the VM in the future. During reversible deactivation of the contralateral visual cortex in cats, we observed that ipsilaterally recorded neurons close to the border between areas 17 and 18 receive selective excitatory callosal input on both ongoing and evoked activity. In detail, neurons responding well to a vertical Gabor patch moving away from the deactivated hemifield decreased prestimulus and stimulus-driven activity much more than those preferring motion toward the cooled hemifield. Further, activity of neurons responding to horizontal lines decreased more than the response to vertical lines. Embedding a single Gabor into a collinear line context selectively stabilized responses, especially when the context was limited to the intact hemifield. These findings indicate that CCs interconnect not only neurons coding for similar orientations but also for similar directions of motion. We conclude that CCs anticipate stimulus features that are potentially relevant for both hemifields (i.e., coherent motion but also collinear shape) because already prestimulus activity and activity to stimuli not crossing the VM revealed feature specificity. Finally, we hypothesize that intrinsic and callosal networks processing different orientations and directions are anisotropic close to the VM facilitating perceptual grouping along likely future motion or (shape) trajectories before the visual stimulus arrives.

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Section: Methodsmentioning

confidence: 99%

Section: A Collinear Context Stabilizes Responses Evoked By Vertical mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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An Updated Midline Rule: Visual Callosal Connections Anticipate Shape and Motion in Ongoing Activity across the Hemispheres

et al. 2013

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“…However, the necessity of higher-level cortices does not forcibly exclude a causal role for low-level cortices. Directly testing this hypothesis is not straightforward, of course, because of the critical role played by V1/V2 in seeing (though see reports on aperceptive agnosia [68,81] and hemianopic patients [82]). Another approach that as yet has not been rigorously applied to IC processing is non-invasive neurostimulation in healthy subjects.…”

Section: Lesion and Neurostimulation Studiesmentioning

confidence: 99%

Illusory contours: a window onto the neurophysiology of constructing perception

Murray

Herrmann

2013

Trends in Cognitive Sciences

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Abstract:Seeing seems effortless, despite needing to segregate and integrate visual information that varies in its quality, quantity, and location. The extent to which seeing passively recapitulates the external world is challenged by phenomena such as illusory contours, an example of visual completion whereby borders are perceived despite their physical absence in the image. Instead, visual completion and seeing are increasingly conceived as active processes, dependent on information exchange across neural populations. How this is instantiated in the brain remains controversial. Divergent models emanate from single-unit and population-level electrophysiology, neuroimaging, and neurostimulation studies. We reconcile discrepant findings from different methods and disciplines, and underscore the importance of taking into account spatio-temporal brain dynamics in generating models of brain function and perception. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation 1 Highlights Illusory contours exemplify core challenges for perception and binding  Competing models stem from diverse neurophysiologic metrics in animals and humans  Consideration of spatio-temporal brain dynamics reconciles these differences 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 AbstractSeeing seems effortless, despite needing to segregate and integrate visual information that varies in its quality, quantity, and location. The extent to which seeing passively recapitulates the external world is challenged by phenomena such as illusory contours, an example of visual completion whereby borders are perceived despite their physical absence in the image.Instead, visual completion and seeing are increasingly conceived as active processes, dependent on information exchange across neural populations. How this is instantiated in the brain remains controversial. Divergent models emanate from single-unit and population-level electrophysiology, neuroimaging, and neurostimulation studies. We reconcile discrepant findings from different methods and disciplines, and underscore the importance of taking into account spatio-temporal brain dynamics in generating models of brain function and perception. KeywordsVisual perception; perceptual completion; binding; object recognition; illusory contour; neuroimaging 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 In what follows, we provide a review of these developments as they pertain to Single-unit StudiesPsychology differentiates sensation from perception (Box 1). Sensation reflects the neural representation of physical properties of stimuli, whereas perception refers to consci...

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An fMRI Investigation of the Cortical Network Underlying Detection and Categorization Abilities in Hemianopic Patients

et al. 2012

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The current study aims to investigate visual scene perception and its neuro-anatomical correlates for stimuli presented in the central visual field of patients with homonymous hemianopia, and thereby to assess the effect of a right or a left occipital lesion on brain reorganization. Fourteen healthy participants, three left brain damaged (LBD) patients with right homonymous hemianopia and five right brain damaged (RBD) patients with left homonymous hemianopia performed a visual detection task (i.e. "Is there an image on the screen?") and a categorization task (i.e. "Is it an image of a highway or a city?") during a block-designed functional magnetic resonance imaging recording session. Cerebral activity analyses of the posterior areas-the occipital lobe in particular-highlighted bi-hemispheric activation during the detection task but more lateralized, left occipital lobe activation during the categorization task in healthy participants. Conversely, in patients, the same network of activity was observed in both tasks. However, LBD patients showed a predominant activation in their right hemisphere (occipital lobe and posterior temporal areas) whereas RBD patients showed a more bilateral activation (in the occipital lobes). Overall, our preliminary findings suggest a specific pattern of cerebral activation depending on the task instruction in healthy participants and cerebral reorganization of the posterior areas following brain injury in hemianopic patients which could depend upon the side of the occipital lesion.

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Impairments of Gestalt perception in the intact hemifield of hemianopic patients are reflected in gamma-band EEG activity

Cited by 43 publications

References 101 publications

An Updated Midline Rule: Visual Callosal Connections Anticipate Shape and Motion in Ongoing Activity across the Hemispheres

An Updated Midline Rule: Visual Callosal Connections Anticipate Shape and Motion in Ongoing Activity across the Hemispheres

Illusory contours: a window onto the neurophysiology of constructing perception

An fMRI Investigation of the Cortical Network Underlying Detection and Categorization Abilities in Hemianopic Patients

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