Two interesting articles

 

On examination, they found that rat vibrissal cortex comprises about 500,000 neurons, the number and 3D distribution being remarkably preserved across animals. More importantly, the number of neurons per cortical column varied between 10,000 and 30,000 within individual animals.
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“Instead, the organization of the cerebral cortex seems to be shaped by the information obtained at the peripheral sensory sheet, a finding that may pertain to other sensory systems and species, including people.-link

 This one suggests that the size of hypercolumns or macrocolumns is not constant but based on input. 

The models suggest that cortical circuitry interconnects most neurons across cortical columns, rather than within and that these “trans-columnar” networks are not uniformly structured: they are highly specialized and integrate signals from multiple sensory receptors.

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 Neurons of all cell types projected the majority of their axon — the part of the neuron that transmits information to other neurons — far beyond the borders of the cortical column they were located in. That means information from a single whisker spreads into multiple cortical columns.-link

 Another interesting finding, showing the importance of transcolumnar connectivity