Bona Silvia, Herbert Andrew, Toneatto Carlo, Silvanto Juha, Cattaneo Zaira
Brain Research Unit, OV Lounasmaa Laboratory, Aalto University School of Science, Espoo, Finland; BioMag Laboratory, HUS Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Finland; Advanced Magnetic Imaging Centre, Aalto Neuroimaging, OV Lounasmaa Laboratory, School of Science, Aalto University, Espoo, Finland.
Department of Psychology, Rochester Institute of Technology, Rochester, NY, USA.
Cortex. 2014 Feb;51:46-55. doi: 10.1016/j.cortex.2013.11.004. Epub 2013 Nov 21.
Despite the fact that bilateral mirror symmetry is an important characteristic of the visual world, few studies have investigated its neural basis. Here we addressed this issue by investigating whether the object-selective lateral occipital (LO) cortex, a key brain region in object and shape processing, is causally involved in bilateral symmetry detection. Participants were asked to discriminate between symmetric and asymmetric dot patterns, while fMRI-guided repetitive TMS was delivered online over either the left LO, the right LO or two control sites in the occipital cortex. We found that the application of TMS over both right and left LO impaired symmetry judgments, with disruption being greater following right LO than left LO TMS, indicative of right hemisphere lateralization in symmetry processing. TMS over LO bilaterally also affected a visual contour detection task, with no evidence for hemispheric difference in this task. Overall, our results demonstrates that LO bilaterally plays a causal role in symmetry detection possibly due to symmetry acting as a strong cue in Gestalt processes mediating object recognition.
尽管双侧镜像对称是视觉世界的一个重要特征，但很少有研究探讨其神经基础。在这里，我们通过研究物体选择性外侧枕叶（LO）皮层（物体和形状处理中的一个关键脑区）是否因果性地参与双侧对称检测来解决这个问题。参与者被要求区分对称和不对称的点阵图案，同时在功能磁共振成像（fMRI）引导下，对左侧LO、右侧LO或枕叶皮层的两个对照部位进行在线重复经颅磁刺激（TMS）。我们发现，对右侧和左侧LO施加TMS都会损害对称判断，右侧LO TMS后的干扰比左侧LO TMS更大，这表明在对称处理中存在右半球偏侧化。双侧LO的TMS也影响了视觉轮廓检测任务，在这个任务中没有半球差异的证据。总体而言，我们的结果表明，双侧LO在对称检测中起因果作用，这可能是因为对称在介导物体识别的格式塔过程中是一个强大的线索。
