Visual plasticity

视觉可塑性
  • 文章类型: Case Reports
    生殖器纹状体通路的受损导致视野相应部分的暗点瘤。这里,我们介绍了一例IB患者的左眼小眼症和大部分的左生殖器纹状体通路的病变,包括外侧膝状核(LGN)。尽管有严重的病变,患者仅在右下半场的外围部分有一个非常狭窄的暗点(超过15°的偏心率),并且在初级视觉皮层中有完整的视野表现。患者视野的人群感受野映射(pRF)显示了有序的偏心率图以及两个半球的对侧激活。扩散束成像,我们揭示了受病变影响的半球中的上丘(SC)和皮质结构之间的联系,这可以介导皮质水平的视网膜异位重组。我们的结果表明,发展中的视网膜图具有惊人的灵活性,其中对侧丘脑接收来自鼻和颞部视网膜的纤维。
    Impairment of the geniculostriate pathway results in scotomas in the corresponding part of the visual field. Here, we present a case of patient IB with left eye microphthalmia and with lesions in most of the left geniculostriate pathway, including the Lateral Geniculate Nucleus (LGN). Despite the severe lesions, the patient has a very narrow scotoma in the peripheral part of the lower-right-hemifield only (beyond 15° of eccentricity) and complete visual field representation in the primary visual cortex. Population receptive field mapping (pRF) of the patient\'s visual field reveals orderly eccentricity maps together with contralateral activation in both hemispheres. With diffusion tractography, we revealed connections between superior colliculus (SC) and cortical structures in the hemisphere affected by the lesions, which could mediate the retinotopic reorganization at the cortical level. Our results indicate an astonishing case for the flexibility of the developing retinotopic maps where the contralateral thalamus receives fibers from both the nasal and temporal retinae.
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  • 文章类型: Journal Article
    Schizophrenia is a severe mental illness with visual learning and memory deficits, and reduced long term potentiation (LTP) may underlie these impairments. Recent human fMRI and EEG studies have assessed visual plasticity that was induced with high frequency visual stimulation, which is thought to mimic an LTP-like phenomenon. This study investigated the differences in visual plasticity in participants with schizophrenia and healthy controls. An fMRI visual plasticity paradigm was implemented, and proton magnetic resonance spectroscopy data were acquired to determine whether baseline resting levels of glutamatergic and GABA metabolites were related to visual plasticity response. Adults with schizophrenia did not demonstrate visual plasticity after family-wise error correction; whereas, the healthy control group did. There was a significant regional difference in visual plasticity in the left visual cortical area V2 when assessing group differences, and baseline GABA levels were associated with this specific ROI in the SZ group only. Overall, this study suggests that visual plasticity is altered in schizophrenia and related to basal GABA levels.
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