Brain-derived neurotrophic factor (BDNF) is a preferred ligand for a
member of the tropomyosin-related receptor family, trkB. Activation of
trkB is implicated in various activity-independent as well as
activity-dependent growth processes in many developing and mature neural
systems. In the subcortical visual system, where electrical activity has
been implicated in normal development, both differential survival, as well
as remodeling of axonal arbors, have been suggested to contribute to
eye-specific segregation of retinal ganglion cell inputs. Here, we tested
whether BDNF is required for eye-specific segregation of visual inputs to
the lateral geniculate nucleus and the superior colliculus, and two other
major subcortical target fields in mice. We report that eye-specific
patterning is normal in two mutants that lack BDNF expression during the
segregation period: a germ-line knockout for BDNF, and a conditional
mutant in which BDNF expression is absent or greatly reduced in the
central nervous system. We conclude that the availability of BDNF is not
necessary for eye-specific segregation in subcortical visual nuclei.