Training-induced cortical representation of a hemianopic hemifield

Henriksson, Linda; Raninen, Antti; Näsänen, Risto; Hyvärinen, Lea; Vanni, Simo

doi:10.1136/jnnp.2006.099374

Cited by 89 publications

(87 citation statements)

References 34 publications

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“…pRFs for patients P1 and P4 increased by ∼30% but only for eccentricities 6-10°. The relative increase in pRF size seen in the contralesional hemisphere may be attributed to loss of input from interhemispheric connections (40)(41)(42), although the expectation that these would affect mainly pRFs along the vertical meridian is not well born out.…”

Section: Discussionmentioning

confidence: 99%

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Population receptive field analysis of the primary visual cortex complements perimetry in patients with homonymous visual field defects

Papanikolaou

Keliris

Papageorgiou

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Injury to the primary visual cortex (V1) typically leads to loss of conscious vision in the corresponding, homonymous region of the contralateral visual hemifield (scotoma). Several studies suggest that V1 is highly plastic after injury to the visual pathways, whereas others have called this conclusion into question. We used functional magnetic resonance imaging (fMRI) to measure area V1 population receptive field (pRF) properties in five patients with partial or complete quadrantic visual field loss as a result of partial V1+ or optic radiation lesions. Comparisons were made with healthy controls deprived of visual stimulation in one quadrant ["artificial scotoma" (AS)]. We observed no large-scale changes in spared-V1 topography as the V1/V2 border remained stable, and pRF eccentricity versus cortical-distance plots were similar to those of controls. Interestingly, three observations suggest limited reorganization: (i) the distribution of pRF centers in spared-V1 was shifted slightly toward the scotoma border in 2 of 5 patients compared with AS controls; (ii) pRF size in spared-V1 was slightly increased in patients near the scotoma border; and (iii) pRF size in the contralesional hemisphere was slightly increased compared with AS controls. Importantly, pRF measurements yield information about the functional properties of spared-V1 cortex not provided by standard perimetry mapping. In three patients, spared-V1 pRF maps overlapped significantly with dense regions of the perimetric scotoma, suggesting that pRF analysis may help identify visual field locations amenable to rehabilitation. Conversely, in the remaining two patients, spared-V1 pRF maps failed to cover sighted locations in the perimetric map, indicating the existence of V1-bypassing pathways able to mediate useful vision.cortical blindness | quadrantanopia | plasticity | retinotopy | hemianopia C ortical damage of the visual pathway often results from posterior or middle cerebral artery infarcts, hemorrhages, and other brain injuries. The most common visual cortex lesions involve the primary visual cortex (V1), the chief relayer of visual information to higher visual areas. Damage to area V1 or its primary inputs leads to the loss of conscious vision in the corresponding region of the contralateral visual hemifield, producing a dense contralateral scotoma that often covers a hemifield (hemianopia) or a single visual field quadrant (quadrantanopia).A much-debated issue is whether the adult V1 is able to reorganize after injury. Reorganization refers to long-term changes in the neuronal circuit (1) and generally requires the growth of new anatomic connections or a permanent change in the strength of existing connections. Several studies report significant remapping in area V1 of patients suffering from macular degeneration and other retinal lesions (2-12). The extent of this remapping has recently been called into question, however (1,(13)(14)(15)(16)(17)(18)(19). Less is known about how the visual system remaps to cover the visual field after injury to a...

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Section: Discussionmentioning

confidence: 99%

“…Previous reports have suggested that in some cases, residual vision in the blind hemifield might be mediated by visual areas in the intact hemisphere (40)(41)(42)(43). It is then possible that after area V1 injury, reorganization might occur in the contralateral, healthy hemisphere.…”

Section: Correspondence Between Visual Field Coverage Maps and Perimementioning

confidence: 95%

Population receptive field analysis of the primary visual cortex complements perimetry in patients with homonymous visual field defects

Papanikolaou

Keliris

Papageorgiou

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…He has developed an effective ability to scan, of which he is aware. One may speculate that his excellent performance in everyday life and as an elite player on the soccer field may be a consequence of scanning or of motion detection in the blind field 9,10 or both. Subjects 2 and 3 both display a scanning eye movement pattern, which does not resemble the inappropriate saccadic intrusions often seen in patients with cerebellar disorders.…”

Section: Discussionmentioning

confidence: 99%

“…8 Motion detection in the blind field has also been described in adults with acquired hemianopia. 9,10 With such compensation mechanisms, we can expect that the practical binocular VF function in everyday living differs from the monocular VF function assessed under strict control of fixation.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms compensating for visual field restriction in adolescents with damage to the retro-geniculate visual system

Jacobson

Lennartsson

Pansell

et al. 2012

Eye

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Background To describe visual field (VF) outcome in three adolescents with damage to the optic radiation and to focus on mechanisms that may compensate the practical functional limitations of VF defects. Design Descriptive, prospective multi-case study in a hospital setting. Participants Three teenagers with cerebral visual dysfunction because of damage to the retro-geniculate visual pathways. Methods Best-corrected visual acuity and eye alignment were assessed. Visual field function was tested with Goldmann perimetry, and with Rarebit, Humphrey Visual Field Analyzer and Esterman computerized techniques. Fixation was registered with video oculography during Rarebit examination. Magnetic resonance imaging of the brain illustrated brain damage and its relation to the posterior visual system. Results One of the three subjects had bilateral asymmetric white matter damage of immaturity, early-onset exotropia, and a relative homonymous VF defect, but normal binocular VF. The second subject also had bilateral asymmetric white matter damage of immaturity and showed an inferior right quadrantanopia, confirmed by the binocular field. Registration of fixation revealed automatic scanning during perimetry. The third subject had an almost total left homonymous hemianopia after resection of a brain tumour in the right temporal lobe. The hemianopia could be compensated for by fast voluntary scanning.

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“…Secondly, the issues of cerebral asymmetries and/or retinotopic organization of spatial frequency processing within the occipital cortex are still being debated in the literature. Many studies reveal retinotopic organization of spatial frequency processing in the occipital cortex [16][17][18]. HSF sinusoidal grating processing, for example, activates the foveal representation in all retinotopic areas (such as V1) of the occipital cortex, and LSF sinusoidal grating processing activates more peripheral representations in the same cortical areas.…”

Section: Introductionmentioning

confidence: 99%