Laminar Organization of Working Memory Signals in Human Visual Cortex

Abstract

The primary visual cortex (V1) not only represents incoming visual information but is also engaged by higher-level cognitive processes such as visual working memory. Given the laminar terminations of feedback connections between brain areas, such internally generated signals are thought to be present selectively in the deep and superficial layers of V1, and avoid the middle layers. Here, we provide empirical support for this notion, using lamina-resolved fMRI in humans. We observed item-specific working memory signals in early visual cortex. In V1, this item-specific activity was selectively present in deep and superficial layers, avoiding the middle layers, while working memory related activity was present in all layers of V2 and V3. These results show for the first time the laminar organization of internally generated signals during visual working memory in the human visual system, and provide new insights into how bottom-up and top-down signals in visual cortex are separated.