Reduced vocal variability in a XXXX model of @entity935 depletion: implications for @entity191 .

@entity1 @entity146 @entity935 @entity191 @entity12128 @entity2955 @entity4149
Midbrain @entity935 (DA) modulates the activity of basal ganglia circuitry important for motor control in a variety of species. In songbirds, DA underlies motivational behavior including reproductive drive and is implicated as a gatekeeper for neural activity governing vocal variability. In the @entity12128 , @entity12128 , DA levels increase in Area X, a song-dedicated subregion of the basal ganglia, when a male bird sings his courtship song to a female (female-directed; FD). Levels remain stable when he sings a less stereotyped version that is not directed toward a conspecific (undirected; UD). Here, we used a mild dose of the neurotoxin @entity2955 ( @entity2955 ) to reduce presynaptic DA input to Area X and characterized the effects on FD and @entity146 . Immunoblots were used to quantify levels of @entity4149 hydroxylase (TH) as a biomarker for DA afferent loss in vehicle- and @entity2955 -injected birds. Following @entity2955 administration, TH signals were lower in Area X but not in an adjacent subregion, ventral striatal-pallidum (VSP). A postsynaptic marker of DA signaling was unchanged in both regions. These observations suggest that effects were specific to presynaptic afferents of vocal basal ganglia. Concurrently, vocal variability was reduced during UD but not FD song. Similar decreases in vocal variability are observed in @entity1 with @entity191 ( @entity191 ), but the link to DA loss is not well-understood. The @entity2955 songbird model offers a unique opportunity to further examine how DA loss in cortico-basal ganglia pathways affects vocal control.
