The goal of my lab is to understand the neural mechanisms that enable us to communicate. This process requires that we perform and perceive complex signals, and we are only beginning to understand how those signals are processed in the central nervous system. Particularly fascinating from a neurobiological perspective are forms of communication that are learned through social interaction, and a very familiar example is the set of sounds that we use in speech. We are born able to produce sound, but we are not born able to produce the nuance complexity of the sounds that we use in adult speech. Instead, we must learn to communicate through speech by listening to the sounds we hear produced by others and refining our imitation of those sounds through trial-and-error rehearsal.
In seeking to understand the neural basis of this learning, we turn to songbirds because they also learn the songs they use in vocal communication through a developmental sequence with striking parallels to how we acquire speech. Birds learn their songs by imitating the songs they hear produced by other members of their species, and young birds go through a “babbling” phase in which they refine their performance of the songs that they will eventually sing as adults. In addition, songbirds possess a discrete set of neural structures specialized for the learning, performance and perception of songs. We employ technology that allows us to eavesdrop on the activity of those neurons as the birds are going about their daily life and are engaged in singing and responding to the songs they hear performed by others. This approach of simultaneously monitoring the activity of individual neurons and the bird’s ongoing behavior provides an essential link in seeking to understand the role of those neurons in generating the behavior.
We have used this technique in the carefully controlled conditions of the laboratory to describe how one and the same song is represented as both a vocal output and an auditory input, providing mechanistic insight into how signals that are heard may be imitated in vocal output. We have also performed field studies of birds in the wild to link that neural activity to the bird’s perception of other birds’ songs. Future studies linking neurophysiology and field study will allow us to take advantage of the diversity of ways that songs are produced (vocal repertoires, song syntax) and used in communication (mate attraction, territorial defense) by birds of different species, relying on those “natural experiments” to explore how higher-order features associated with the recognition and interpretation of various signals may also be encoded in the brain.