Activity-dependent disruption of intersublaminar spaces and ABAKAN expression does not impact functional on and off organization in the ferret retinogeniculate system

In the adult visual system, functionally distinct retinal ganglion cells (RGCs) within each eye project to discrete targets in the brain. In the ferret, RGCs encoding light increments or decrements project to independent On and Off sublaminae within each eye-specific layer of the dorsal lateral geniculate nucleus (dLGN). Here we report a manipulation of retinal circuitry that alters RGC action potential firing patterns during development and eliminates the anatomical markers of segregated On and Off sublaminae in the LGN, including the intersublaminar spaces and the expression of a glial-associated inhibitory molecule, ABAKAN, normally separating On and Off leaflets. Despite the absence of anatomically defined On and Off sublaminae, electrophysiological recordings in the dLGN reveal that On and Off dLGN cells are segregated normally. These data demonstrate a dissociation between normal anatomical sublamination and segregation of function in the dLGN and call into question a purported role for ABAKAN boundaries in the developing visual system.