Department of Education and Psychology, Freie Universität Berlin, Berlin, Germany.
Berlin School of Mind and Brain, Humboldt-Universität zu Berlin, Berlin, Germany.
Commun Biol. 2021 Sep 14;4(1):1069. doi: 10.1038/s42003-021-02582-4.
Primary visual cortex (V1) in humans is known to represent both veridically perceived external input and internally-generated contents underlying imagery and mental rotation. However, it is unknown how the brain keeps these contents separate thus avoiding a mixture of the perceived and the imagined which could lead to potentially detrimental consequences. Inspired by neuroanatomical studies showing that feedforward and feedback connections in V1 terminate in different cortical layers, we hypothesized that this anatomical compartmentalization underlies functional segregation of external and internally-generated visual contents, respectively. We used high-resolution layer-specific fMRI to test this hypothesis in a mental rotation task. We found that rotated contents were predominant at outer cortical depth bins (i.e. superficial and deep). At the same time perceived contents were represented stronger at the middle cortical bin. These results identify how through cortical depth compartmentalization V1 functionally segregates rather than confuses external from internally-generated visual contents. These results indicate that feedforward and feedback manifest in distinct subdivisions of the early visual cortex, thereby reflecting a general strategy for implementing multiple cognitive functions within a single brain region.
人类初级视皮层（V1）已知既可以表示真实感知到的外部输入，也可以表示表象和心理旋转等内在生成的内容。然而，目前尚不清楚大脑如何将这些内容区分开来，从而避免感知和想象的混合，这可能会导致潜在的不利后果。受神经解剖学研究的启发，这些研究表明 V1 的前馈和反馈连接终止于不同的皮层层，我们假设这种解剖结构的分区分别是外部和内部生成的视觉内容功能分离的基础。我们使用高分辨率的层特异性 fMRI 在心理旋转任务中测试了这一假设。我们发现，旋转的内容主要出现在外皮层深度箱（即浅层和深层）。同时，感知的内容在中层皮层箱中表现得更强。这些结果表明，通过皮层深度分区，V1 可以对外部和内部生成的视觉内容进行功能区分，而不是将它们混淆。这些结果表明，前馈和反馈在早期视觉皮层的不同细分部分表现出来，从而反映了在单个脑区中实现多种认知功能的一般策略。
