Are there neural loops within a column or an area of the cortex? Neuronal networks can make loops because a neuron has a direction (from dendrite to axon).

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?
I've read evidence for single-neuron, two-neuron, and larger loops/cycles throughout the cortex, including intralaminar, interlaminar, and interareal neural loops. But it would take me far too long to back that statement up.

Instead, I offer a list of papers to get you started. I've read all these papers, and they all provide evidence for neural loops in the cortex, especially two-neuron loops. Within these papers, search for "loop", "reciprocal", and, if you're interested in single-neuron loops, "autapse".

References


  
  Alonso, J.-M. (2002) Neural Connections and Receptive Field Properties in the Primary Visual Cortex. The Neuroscientist. 8(5):443-456
  Feldmeyer, D. (2012) Excitatory Neuronal Connectivity in the Barrel Cortex. Frontiers in Neuroanatomy. 6(24):1-22
  Rockland, K.S. and Knutson, T. (2000) Feedback Connections from Area MT of the Squirrel Monkey to Areas V1 and V2. The Journal of Comparative Neurology. 425:345-368
  Thomson, A.M., West, D.C., Wang, Y., and Bannnister, A.P. (2002) Synaptic Connections and Small Circuits Involving Excitatory and Inhibitory Neurons in Layers 2-5 of Adult Rat and Cat Neocortex: Triple Intracellular Recordings and Biocytin Labelling In Vitro. Cerebral Cortex. 12:936-953