Deafening-induced rapid changes to spine synaptic connectivity in the adult avian vocal basal ganglia

The basal ganglia have been implicated in auditory-dependent vocal learning and plasticity in human and songbirds,but the underlying neural phenotype remains to be clarified.Here,using confocal imaging and three-dimensional electron microscopy,we investigated striatal structural plasticity in response to hearing loss in Area X,the avian vocal basal ganglia,in adult male zebrafinch(Taeniopygia guttata).We observed a rapid elongation of dendritic spines,by approximately 13%,by day 3 after deafening,and a considerable increase in spine synapse density,by approximately 61%,by day 14 after deafening,compared with the controls with an intact cochlea.Thesefind-ings reveal structural sensitivity of Area X to auditory deprivation and suggest that this striatal plasticity might contribute to deafening-induced changes to learned vocal behavior.