Efficiency of orientation channels in the striate cortex for distributed categorization process

The primary visual cortex neurophysiology shows a columnar organization tuned to different spatial frequency and different orientation sensitivities (De Valois & De Valois, 1988). Moreover, striate cortex provides a larger number of cells dedicated to vertical and horizontal orientations which generates an over-representation of those orientations in the human visual system (Mansfield, 1974). Complementary to those researches, statistics of the power spectra of natural scene images have shown that vertical and horizontal orientations are most present in the visual environment (Field, 1987; Van der Schaaf & Van Hateren, 1996). The over-representation of horizontal and vertical orientations column in the visual cortex was interpreted as an adaptation of the visual system to this broader amount of information (Van der Schaaf & Van Hateren, 1996). The present study is an attempt to show that this two orientation information are quantitatively effectively more available in the environment (natural scenes), but moreover, vertical information is qualitatively more efficient for a model of categorization.