Van Rinsveld Amandine, Wens Vincent, Guillaume Mathieu, Beuel Anthony, Gevers Wim, De Tiège Xavier, Content Alain
Center for Research in Cognition and Neurosciences (CRCN), UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels 1050, Belgium.
Laboratoire de Cartographie fonctionnelle du Cerveau (LCFC), UNI - ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels 1070, Belgium.
Cereb Cortex Commun. 2021 Apr 7;2(2):tgab028. doi: 10.1093/texcom/tgab028. eCollection 2021.
Humans and other animal species are endowed with the ability to sense, represent, and mentally manipulate the number of items in a set without needing to count them. One central hypothesis is that this ability relies on an automated functional system dedicated to numerosity, the perception of the discrete numerical magnitude of a set of items. This system has classically been associated with intraparietal regions, however accumulating evidence in favor of an early visual number sense calls into question the functional role of parietal regions in numerosity processing. Targeting specifically numerosity among other visual features in the earliest stages of processing requires high temporal and spatial resolution. We used frequency-tagged magnetoencephalography to investigate the early automatic processing of numerical magnitudes and measured the steady-state brain responses specifically evoked by numerical and other visual changes in the visual scene. The neuromagnetic responses showed implicit discrimination of numerosity, total occupied area, and convex hull. The source reconstruction corresponding to the implicit discrimination responses showed common and separate sources along the ventral and dorsal visual pathways. Occipital sources attested the perceptual salience of numerosity similarly to both other implicitly discriminable visual features. Crucially, we found parietal responses uniquely associated with numerosity discrimination, showing automatic processing of numerosity in the parietal cortex, even when not relevant to the task. Taken together, these results provide further insights into the functional roles of parietal and occipital regions in numerosity encoding along the visual hierarchy.
人类和其他动物物种具备一种能力，即无需计数就能感知、表征并在脑海中处理一组物品的数量。一个核心假说是，这种能力依赖于一个专门用于处理数量的自动化功能系统，即对一组物品离散数值大小的感知。传统上，这个系统与顶叶区域相关联，然而，越来越多支持早期视觉数字感的证据对顶叶区域在数量处理中的功能作用提出了质疑。在处理的最早阶段，要在其他视觉特征中专门针对数量进行处理，需要高时间和空间分辨率。我们使用频率标记脑磁图来研究数字大小的早期自动处理，并测量视觉场景中数字和其他视觉变化专门诱发的稳态脑反应。神经磁反应显示了对数量、总占用面积和凸包的隐性辨别。与隐性辨别反应相对应的源重建显示，沿着腹侧和背侧视觉通路有共同和独立的源。枕叶源证明数量的感知显著性与其他可隐性辨别的视觉特征相似。至关重要的是，我们发现顶叶反应与数量辨别独特相关，表明即使与任务无关，顶叶皮层中数量也能自动处理。综上所述，这些结果为顶叶和枕叶区域在视觉层级中数量编码的功能作用提供了进一步的见解。
