Probing top-down information in neocortical layer 1

Accurate perception of the environment is a constructive process that requires inte-gration of external bottom-up sensory signals with internally generated top-down information. Decades of work have elucidated how sensory neocortex processes physical stimulus features. By contrast, examining how top-down information is encoded and integrated with bottom-up signals has been challenging using tradi-tional neuroscience methods. Recent technological advances in functional imaging of brain-wide afferents in behaving mice have enabled the direct measurement of top-down information. Here, we review the emerging literature on encoding of these internally generated signals by different projection systems enriched in neo-cortical layer 1 during defined brain functions, including memory, attention, and pre-dictive coding. Moreover, we identify gaps in current knowledge and highlight future directions for this rapidly advancing field.

Automated summary

Accurate perception of the environment involves integrating sensory signals with internally generated information. Recent advances in brain imaging techniques allow for the study of how top-down information is encoded and integrated with bottom-up signals.