Early visual cortex as a multiscale cognitive blackboard.

Neurons in early visual cortical areas not only represent incoming visual information
but are also engaged by higher level cognitive processes, including
attention, working memory, imagery, and decision-making. Are these cognitive
effects an epiphenomenon or are they functionally relevant for these
mental operations? We review evidence supporting the hypothesis that the
modulation of activity in early visual areas has a causal role in cognition. The
modulatory influences allow the early visual cortex to act as a multiscale cognitive
blackboard for read and write operations by higher visual areas, which
can thereby efficiently exchange information. This blackboard architecture
explains how the activity of neurons in the early visual cortex contributes to
scene segmentation and working memory, and relates to the subject’s inferences
about the visual world. The architecture also has distinct advantages
for the processing of visual routines that rely on a number of sequentially
executed processing steps.