Decoding auditory cognition: Unraveling the corticostriatal-SNr circuit's role in frequency discrimination accuracy.

The anterior auditory field (AAF) is critical for auditory discrimination, though underlying neural pathways remain unclear. Using viral tracing, optogenetics/pharmacogenetics, and behavior, we investigated the corticostriatal-substantia nigra pars reticulata (SNr) circuit's role in frequency discrimination. AAF excitatory neurons, synapsing on caudate putamen (CPu) GABAergic neurons, were highly active during tasks. Pharmacogenetic suppression of AAF→CPuGABA projections impaired discrimination performance. We further identified an AAF→CPu D1-medium spiny neuron (MSN) pathway regulating discrimination; its pharmacogenetic/optogenetic inhibition caused deficits. Histology confirmed CPuD1→SNr projections. Critically, suppressing/ablating AAF→CPu→SNr circuit neurons severely disrupted accuracy. Fiber photometry revealed SNrGABA neuron activation during tasks. Together, AAF→CPuD1 projections and the AAF→CPu→SNr circuit are pivotal for frequency discrimination, advancing mechanistic insights into auditory processing circuits.