Column structure of inferotemporal cortex: "visual alphabet" or "differential amplifiers"?

Cells in the inferotemporal cortex (area TE) selectively respond to complex visual object-features, and those which respond to similar features cluster in a columnar region elongated vertical to the cortical surface. What are the functional roles of the column structure in the inferotemporal cortex? Selectivity of cells within a column is not identical, though similar. If we emphasize the similarity among cells within a column, we can regard the columns as units for description of object features. Because the features represented by columns are still partial features of images of objects, the representation of images of objects require combination of multiple columns. Thus, we can compare the set of columns in the inferotemporal cortex to "visual alphabet". Alternatively, if we emphasize the differences in selectivity of cells within a column, the columns can be compared to "differential amplifiers" each of which represents variety within a group of features. The enormous number of objects present in nature can be described by combining outputs of the multiple differential amplifiers in the inferotemporal cortex. Whether or not these hypotheses are valid can be tested by investigating new column structures created by artificial training.