Neural properties of fundamental function encoding of sound selectivity in the female avian auditory cortex

Zebra finches (Taeniopygia guttata) use their voices for communication. Song structures in the songs of individual males are important for sound recognition in females. The caudomedial mesopallium (CMM) and nidopallium (NCM) are known to be essential higher auditory regions for sound recognition. These two regions have also been discussed with respect to their fundamental functions and song selectivity. To clarify their functions and selectivity, we investigated latencies and spiking patterns and also developed a novel correlation analysis to evaluate the relationship between neural activity and the characteristics of acoustic factors. We found that the latencies and spiking patterns in response to song stimuli differed between the CMM and NCM. In addition, our correlation analysis revealed that amplitude and frequency structures were important temporal acoustic factors for both regions. Although the CMM and NCM have different fundamental functions, they share similar encoding systems for acoustic factors. The caudomedial mesopallium (CMM) and nidopallium (NCM) in avian brains are known to be essential higher auditory regions for sound recognition in female songbirds. Auditory neurons in these two regions showed different latency of first spike. Furthermore, our novel developed analysis “time series correlation” revealed that specific acoustic factors including amplitude, mean frequency, and Wiener entropy were strongly selective in auditory neurons of CMM and NCM.