Figure 18.

Ocular dominance columns form without eyes. (a) In control ferrets, biotinylated dextran amine was injected into the lateral geniculate nucleus, yielding ocular dominance columns in coronal sections through the visual cortex. Serial sections were aligned and drawn to provide a 2D view of the columns. (b) Enucleation was performed at birth, before geniculate afferents innervate the cortex. Despite this manipulation, ocular dominance columns were present after tracer injection into the lateral geniculate nucleus at 2 months of age (Crowley & Katz 1999).