Physiological Studies in Deafferented Visual Cortex Cells of Cats Following Transplantation of Fetal Xenografts from the Rat's Cortex

Yinon, U.; Shemesh, Rachel; Arda, H. Efsun; Dobin, G.; Jaros, Peter P.

doi:10.1006/exnr.1993.1133

Cited by 6 publications

(7 citation statements)

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“…They did not observe any change in the profile of functional fMRI signal activity across the LPZ border. These results agree with Yinon et al 76who reported little reorganization following deafferentation of adult cat V1 by interrupting geniculo-cortical afferents. The fMRI measurements also agree with prior results from studies measuring CO activity, another metabolic marker57.…”

Section: V1 Inputs From the Two Eyessupporting

confidence: 93%

Plasticity and stability of visual field maps in adult primary visual cortex

2009

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Preface It is important to understand the balance between cortical plasticity and stability in various systems and spatial scales in the adult brain. We review measurements of adult plasticity in primary visual cortex (V1), a structure that has a key role in distributing visual information. There are claims of plasticity at multiple spatial scales in adult V1, but many inconsistencies in the data raise questions about the extent and nature of such plasticity. Understanding is further limited by a lack of quantitative models to guide the interpretation of the data. These problems limit efforts to translate research findings about adult cortical plasticity into significant clinical, educational and policy applications.

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Section: V1 Inputs From the Two Eyessupporting

confidence: 93%

Plasticity and stability of visual field maps in adult primary visual cortex

2009

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“…In this respect, the results support previous findings [24][25][26]31] and confirm the inability of the mature visual cortex to adapt their structural organization to the altered circumstances.…”

Section: Discussionsupporting

confidence: 92%

“…Most of the above-described methods are identical to those previously used in the laboratory [30][31][32].…”

Section: Methodsmentioning

confidence: 98%

Columnar organization of the mammalian visual cortex and its vulnerability following lesion in adult cats

Gurshumov

Yinon²

2005

Brain Injury

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It is well known that in the mammalian visual cortex the neurons, sharing similar response properties, are grouped together into functional units, known as cortical columns. The orientation and ocular dominance columnar organization is a fundamental element for both the anatomical and physiological features of the visual cortex. Nonetheless, little is known about the functional restoration of matured columnar columns following injury. In the present study, the visual cortex of adult cats was studied electrophysiologically, whereas the primary goal of the study was to reveal the functional stability of the columns, disconnected from the main visual input. Experiments were performed on the primary visual cortex (area 17) of 13 anaesthetized and paralyzed adult cats. The columnar distortion was produced by surgical incision perpendicular to the cortical columns. The single unit activity was recorded from 1186 visual cells (experimental groups) in areas proximal and distal to the lesion and, compared to data, received from intact visual cortex (control group). The results indicate that most of the visually responsive cells were found to be selective to specific orientation in all experimental groups (75-100%) similar to the normal control group (78%). Moreover, the distribution of orientation-specific cells was very similar in all experimental and control groups (p > 0.05), as well as in both recording areas (p > 0.05). The percentage of binocular cells was significantly lower in all experimental groups (23-49%) in comparison to the control (80%). However, the distribution of the binocular cells revealed the significant similarity between the experimental and control groups (p > 0.05). An additional finding of the study is that the visual responsiveness of cells was significantly reduced in all experimental groups: only 28-49% of cells were found to be responsive following injury, as compared to 86% in normal control group (p < 0.001). The distribution of cells has also been analysed in accordance with their directional specificity and it has been found that the majority of cells in the experimental groups were found to be bias and non-specific to light stimuli (52-84%) as compared normal controls (21%) (p < 0.001). It has been concluded that, despite the fact that no improvement in visual function was found, the inherent structure of the disrupted cortical columns in the visual cortex was generally preserved. Therefore, the disruption of the columnar connection does not lead to remarkable distortion of the connectivity pattern on the whole, though it does reduce the responsiveness level there. It was concluded that the columnar structure for both orientation and ocular dominance is characterized by high stability, which enables visual processing with minimal brain connections.

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“…Smaller, shortterm changes (2 d after the lesion) have been reported as well (24). As expected, reorganization is more extensive in young animals (23,25) compared with adults (26). A change in the balance between excitation and inhibition may underlie this functional reorganization (27)(28)(29)(30)(31).…”

mentioning

confidence: 59%

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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Physiological Studies in Deafferented Visual Cortex Cells of Cats Following Transplantation of Fetal Xenografts from the Rat's Cortex

Cited by 6 publications

References 0 publications

Plasticity and stability of visual field maps in adult primary visual cortex

Plasticity and stability of visual field maps in adult primary visual cortex

Columnar organization of the mammalian visual cortex and its vulnerability following lesion in adult cats

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

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