Seasonal female processing of social/sexual vocal signals is state dependent
Abstract
Communication requires adaptability to the interlocutors' characteristics and variations, from mere behavioural flexibility to more profound brain plasticity. While plasticity in central processing has been mostly observed early in life - during development, the need for adaptation is present throughout the life, especially in social species for which breeding periods (intersexual signals prevail) are interspersed with more "social" (non sexual) periods.
Birdsong is a typical communication signal whose structure, output and function may change over the year. Here we investigated whether female European starlings’ primary auditory area (Field L) was tuned to these changes. Electrophysiological recordings revealed that Field-L auditory neurons were highly responsive to song elements that are crucial for intra-sexual social interactions during the non-breeding period, while they were highly responsive to male song elements involved in mate attraction during the breeding time.
This adult plasticity in a primary sensory area, with responsiveness differing from time periods when individuals are tuned to social cues to periods when they are tuned to sexual cues, opens an interesting line of research that may be of interest for all social species, including humans, which all undergo such shifts of interest over time.
The processing of these functionally relevant song elements reflect a high level of vigilance. In order to test this hypothesis we did the same recordings under anesthesia and found a clear impact of anesthesia on sensory and cognitive processes. Anesthesia induced an atypical increased neuronal responses towards biologically irrelevant sounds and prevented the seasonal neuronal tuning towards functionally relevant species-specific song elements.