Population receptive field analysis of the primary visual cortex complements perimetry in patients with homonymous visual field defects
Population receptive field analysis of the primary visual cortex complements perimetry in patients with homonymous visual field defects
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DOI：
10.1073/pnas.1317074111
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发表时间：
2014-04-22
影响因子：
11.1
通讯作者：
Smirnakis, Stelios M.
中科院分区：
文献类型：
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作者：
Papanikolaou, Amalia;Keliris, Georgios A.;Smirnakis, Stelios M.
初级视觉皮层 (V1) 损伤通常会导致对侧视觉半视野（暗点）的相应同名区域丧失意识视力。多项研究表明，视觉通路损伤后 V1 具有高度可塑性，而其他研究则对这一结论提出了质疑。我们使用功能磁共振成像 (fMRI) 来测量 5 名由于部分 V1+ 或视放射损伤而导致部分或完全象限视野丧失的患者的 V1 区域群体感受野 (pRF) 特性。与在一个象限中剥夺视觉刺激的健康对照进行比较[“人工暗点”(AS)]。我们观察到，由于 V1/V2 边界保持稳定，幸存的 V1 地形没有发生大规模变化，并且 pRF 偏心率与皮质距离图与对照组相似。有趣的是，三个观察结果表明重组有限：(i) 与 AS 对照相比，5 名患者中有 2 名患者中 pRF 中心的分布稍微向暗点边界移动； (ii) 在靠近暗点边界的患者中，spared-V1 的 pRF 大小略有增加； (iii) 与 AS 对照相比，对侧半球的 pRF 大小略有增加。重要的是，pRF 测量可提供有关备用 V1 皮层功能特性的信息，而标准视野测量图无法提供这些信息。在三名患者中，幸存的 V1 pRF 图与周边暗点的密集区域显着重叠，表明 pRF 分析可能有助于识别适合康复的视野位置。相反，在其余两名患者中，幸存的 V1 pRF 图未能覆盖视野图中的视力位置，表明存在能够介导有用视力的 V1 旁路通路。
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.