Summary diagram illustrating the patterns of afferent projections from DNLL to the central nucleus of IC in three groups: control (A), unilateral cochlear ablation (B), and bilateral cochlear ablation (C). Only a simplified schematic of ascending projections is included simplicity. Crossed projections from DNLL are shown as black symbols and shaded bands in IC and uncrossed projections as open symbols and bands. The hypothesized affects of cochlear influence on presynaptic and postsynaptic activity in the left and right IC in each condition are indicated by the direction of the arrows. The DNLL projections in the bilateral ablation condition, both deprived of cochlear influence, and the deprived DNLL projections to the IC ipsilateral to the unilateral cochlear ablation are not segregated into distinct bands as in the control condition. Together, results of bilateral and unilateral cochlear ablation are consistent with a role of non-Hebbian spontaneous activity-dependent regulation of afferent segregation. Other abbreviations: Co, cochlea; SOC, superior olivary complex.