  The sequential analysis of information in a coarse-to-fine manner is a
fundamental mode of processing in the visual pathway. Spatial frequency (SF)
tuning, arguably the most fundamental feature of spatial vision, provides
particular intuition within the coarse-to-fine framework: low spatial
frequencies convey global information about an image (e.g., general
orientation), while high spatial frequencies carry more detailed information
(e.g., edges). In this paper, we study the development of cortical spatial
frequency tuning. As feedforward input from the lateral geniculate nucleus
(LGN) has been shown to have significant influence on cortical coarse-to-fine
processing, we present a firing-rate based thalamocortical model which includes
both feedforward and feedback components. We analyze the relationship between
various model parameters (including cortical feedback strength) and responses.
We confirm the importance of the antagonistic relationship between the center
and surround responses in thalamic relay cell receptive fields (RFs), and
further characterize how specific structural LGN RF parameters affect cortical
coarse-to-fine processing. Our results also indicate that the effect of
cortical feedback on spatial frequency tuning is age-dependent: in particular,
cortical feedback more strongly affects coarse-to-fine processing in kittens
than in adults. We use our results to propose an experimentally testable
hypothesis for the function of the extensive feedback in the corticothalamic
circuit.
