We investigated the neural mechanism of the processing of three-dimensional (3D) shapes defined by disparity and perspective. We measured blood oxygenation level-dependent signals as participants viewed and classified 3D images of convex–concave shapes. According to the cue (disparity or perspective) and element type (random dots or black and white dotted lines), three types of stimuli were used: random dot stereogram, black and white dotted lines with perspective, and black and white dotted lines with binocular disparity. The blood oxygenation level-dependent images were then classified by multivoxel pattern analysis. To identify areas selective to shape, we assessed convex–concave classification accuracy with classifiers trained and tested using signals evoked by the same stimulus type (same cue and element type). To identify cortical regions with similar neural activity patterns regardless of stimulus type, we assessed the convex–concave classification accuracy of transfer classification in which classifiers were trained and tested using different stimulus types (different cues or element types). Classification accuracy using the same stimulus type was high in the early visual areas and subregions of the intraparietal sulcus (IPS), whereas transfer classification accuracy was high in the dorsal subregions of the IPS. These results indicate that the early visual areas process the specific features of stimuli, whereas the IPS regions perform more generalized processing of 3D shapes, independent of a specific stimulus type.

我们研究了由视差和透视定义的三维 (3D) 形状处理的神经机制。当参与者观看凸凹形状的 3D 图像并对其进行分类时，我们测量了血氧水平相关信号。根据提示（视差或透视）和元素类型（随机点或黑白虚线），使用三种类型的刺激：随机点立体图、透视黑白虚线和双眼黑白虚线差距。然后通过多体素模式分析对血氧水平依赖性图像进行分类。为了识别对形状有选择性的区域，我们使用由相同刺激类型（相同线索和元素类型）引起的信号进行训练和测试的分类器来评估凸凹分类的准确性。为了识别具有相似神经活动模式的皮质区域（无论刺激类型如何），我们评估了转移分类的凸凹分类准确性，其中使用不同刺激类型（不同的线索或元素类型）来训练和测试分类器。使用相同刺激类型的分类精度在早期视觉区域和顶内沟 (IPS) 子区域中较高，而转移分类精度在 IPS 的背侧子区域中较高。这些结果表明，早期视觉区域处理刺激的特定特征，而 IPS 区域则执行更通用的 3D 形状处理，与特定的刺激类型无关。