What's the smallest area in the cortex where we can find a loop and what are these loops?
I understand there are loops between different cortical areas through the white matter.
Experiments, like this one, show there are interactions between cortical layers. But it doesn't necessary mean there are loops.
Other experiments, like this one, looking at signals propagation in pieces of cortex with a cut showed the propagation could somehow circumvent the cut and keep propagating. Again it shows the existence of some local circuits but not necessarily loops.
Do we have a proof of local loops in the cortex? How large a piece of cortex has to be to contain a loop? What are these loops?