Early development of ocular dominance columns. Crowly JC, Katz LC. Science 2000;290:1321–1324.

Abstract

The segregation of lateral geniculate nucleus (LGN) axons into ocular dominance columns is believed to involve a prolonged, activity-dependent sorting process. However, visualization of early postnatal ferret LGN axons by direct LGN tracer injections revealed segregated ocular dominance columns less than seven days after innervation of layer four. These early columns were unaffected by experimentally induced imbalances in retinal activity, implying that different mechanisms govern initial column formation and their modification during the subsequent critical period. Instead of activity-dependent plasticity, the authors propose that ocular dominance column formation relies on the targeting of distinct axonal populations to defined locales in cortical layer four. This study shows that ocular dominance columns in ferrets appear long before the columns can be modified by visual experience. The data presented suggests that neural activity from the eyes has little influence over the formation of the columns, questioning the earlier work of Hubel and Wiesel.—Hans E. Grossniklaus