Department of Psychology, University of Toronto, Toronto, Ontario, Canada.
Cereb Cortex. 2010 Nov;20(11):2568-82. doi: 10.1093/cercor/bhq004. Epub 2010 Feb 11.
Recent evidence suggests that the perirhinal cortex is involved in perception of complex objects with ambiguous features. Anterior regions of the temporal lobes, including the perirhinal cortex as well as lateral cortex, are also thought to play a critical role in semantic memory. To understand how semantic factors might contribute to perceptual discrimination of complex objects, we studied visual object discrimination in patients with semantic dementia (SD)-a neurodegenerative condition characterized by progressive deterioration of semantic knowledge and atrophy to anterior temporal lobes (including perirhinal cortex). In 3 experiments, we assessed discrimination of meaningful (e.g., familiar real-world objects) and novel (e.g., blobs) objects with varying feature ambiguity levels. In a fourth experiment, we compared SD patients with amnesic patients with nonprogressive medial temporal lobe (MTL) lesions and less impaired semantic memory. Across studies, patients with perirhinal damage were impaired at discriminating objects with a high, but not low, degree of feature ambiguity, consistent with previous work indicating a perceptual role for this structure. Stimulus meaningfulness, however, differentially influenced performance in SD patients compared with MTL amnesics, suggesting that perceptual representations of complex objects (dependent upon perirhinal cortex) interact with higher-order abstract conceptual representations, even for tasks with no overt semantic component.
最近的证据表明，边缘系统前皮质参与了具有模糊特征的复杂物体的感知。颞叶的前部区域，包括边缘系统前皮质和外侧皮质，也被认为在语义记忆中起着关键作用。为了了解语义因素如何有助于复杂物体的知觉辨别，我们研究了语义痴呆（SD）患者的视觉物体辨别能力 - 一种以语义知识进行性恶化和前颞叶（包括边缘系统前皮质）萎缩为特征的神经退行性疾病。在 3 项实验中，我们评估了具有不同特征模糊程度的有意义（例如，熟悉的现实世界物体）和新颖（例如，斑点）物体的辨别能力。在第四个实验中，我们将 SD 患者与非进行性内侧颞叶（MTL）病变和语义记忆受损程度较低的遗忘症患者进行了比较。在所有研究中，边缘系统前皮质损伤的患者在辨别具有高而非低特征模糊程度的物体时存在障碍，这与先前的工作一致，表明该结构具有感知作用。然而，与 MTL 遗忘症患者相比，SD 患者的刺激意义不同程度地影响了他们的表现，这表明复杂物体的知觉表示（依赖于边缘系统前皮质）与更高阶的抽象概念表示相互作用，即使对于没有明显语义成分的任务也是如此。
