3. Modulation of auditory and motor processing by social context:

Previous accomplishments: Processing of courtship signals (visual and auditory) and the generation of appropriate behavioral responses are highly dependent on social context.  Using the male zebra finch, my laboratory has spent much effort examining the neural mechanisms that regulate auditory processing across different behavioral states (Margoliash and Schmidt, 2010; Lewandowski et al., 2013). We have shown that auditory responsiveness in specific areas of the “song system” can be modulated by arousal (Cardin and Schmidt, 2003; Cardin et al., 2005) in a manner that is dependent on local release of the neuromodulator norepinephrine (Cardin and Schmidt, 2004; Castelino and Schmidt, 2010). We have also shown that auditory response properties in awake behaving birds are dramatically different from those observed in sedated birds, not only in their response strength but also in their tuning properties (Raskin et al., 2012). These findings imply that norepinephrine is able to reconfigure sensory response properties in targeted brain areas in a way that is precisely aligned with the animal’s behavioral state. In addition to its role in sensory processing, our recent work has shown that norepinephrine can also regulate motor (song) output (Glaze et al., 2017). By targeting nucleus RA in the singing bird, we have shown that local infusion of norepinephrine causes changes in song properties that are identical to those observed while singing under different social contexts.


Current studies: All of our previous work was performed in male songbirds and changes in behavioral state were achieved primarily by manipulating arousal level in single individuals. Because auditory response properties can be modulated by simple changes in arousal, we hypothesize that similar modulation also is likely during more ethologically-relevant conditions. We decided to investigate this hypothesis in the female cowbird rather than the male, because females are particularly tuned to vocal interactions between males during the breeding season often using these vocal exchanges as a way to evaluate potential mates. We plan to record neural activity from auditory forebrain and “song control” areas from freely moving female cowbirds in our smart aviary and investigate how social context changes auditory responsiveness. These experiments will necessitate wireless recording methodology that can be synched with the acoustic and visual signals captured by our computational system. We are currently in the process of adapting/developing this technology.


Future directions: Our aim is to develop a computer capture system that can provide, for any given moment in time, detailed information about the positional information of all member in the group, their social relationships and both immediate and past visual and acoustic social interactions. From the perspective of a given female listening to the song of a male, this would provide information regarding the social context in which she hears that song. This would allow the investigation of how social context might affect neural processing in auditory/motor areas as well as monitor moment-to-moment changes in hormone (e.g. estrogen) or neuromodulator (e.g. norepinephrine, dopamine) levels in targeted brain areas that control courtship behavior.