THE ROLE OF NEWBORN NEURONS FOR THE SONG VARIABILITY IN THE ADULT BENGALESE FINCH

The adult neurogenesis is essential for maintaining neural plasticity and cognitive functions. In songbirds, new neurons integrate into the forebrain nuclei AreaX and HVC, crucial for vocal learning and production, respectively. Our previous work in the songbird Bengalese finch (Lonchura striata domestica) showed that the higher number of newborn neurons in these areas is associated with singing more variable song. The causal relationship of neurogenesis and learned birdsong, however, remains unclear. In this study, we manipulated neurogenesis and investigated its effect on song variability in adult male Bengalese finches.
We used 32 males divided into 3 groups according to the type of substance administered intramuscularly for 4 weeks: saline (control, n=9), memantine (MEM, n=9), or temozolomide (TMZ, n=14). New cells were labeled with the proliferation markers 5-bromo-2′-deoxyuridine (BrdU) and 5-ethynyl-2′-deoxyuridine (EdU) and the birds were sacrificed at six weeks.
We found that the substances significantly affected the number of dividing cells in the neurogenic ventricular zone and the number of new neurons in vocal areas. Compared to controls, MEM increased the cell counts, while TMZ decreased them. TMZ reduced song sequence variability, leading to more stable, linear songs. It also decreased the number of syllables, transitions, and motifs. The effect of MEM on song variability was bidirectional.
These findings suggest that MEM and TMZ influence neurogenesis, and that newly generated neurons contribute to variability in song sequences.
This study is supported by APVV-20-0344, VEGA 2/0150/24 and APP0532.