1. Research

My lab investigates the neural mechanisms underlying vocal learning, motor control, and social behavior in songbirds.

SOCIAL MODULATION OF VOCAL LEARNING

Social interactions promote and guide vocal learning in songbirds as well as humans. For example, social interactions with a live tutor can facilitate and guide the trajectory of song development. I am interested in understanding the neural circuits that mediate such social influences on vocal learning. We have recently discovered that midbrain and hindbrain areas that synthesize dopamine and norepinephrine are differentially active when birds are socially tutored (Chen et al., PNAS, 2016). We are now investigating the brain areas in which dopamine and norepinephrine act to promote song learning.  

SOCIAL MODULATION OF VOCAL PERFORMANCE

The structure and organization of vocal signals varies across social contexts in songbirds, humans, and a number of other species. For example, Bengalese finches produce faster songs with more stereotyped syllables arranged in more stereotyped sequences when singing to a female than when singing in isolation (Sakata, Hampton, and Brainard, J. Neurophysiology, 2008; Sakata and Brainard, J. Neurophysiology, 2009). The circuits that modulate the distinct forms of vocal motor change remain largely unknown, though some of our previous studies indicate that distinct circuits control spectral and temporal features of song (Hampton, Sakata, and Brainard, 2009). Using immediate early gene immunohistochemistry, neurophysiological recordings, and manipulations of neural activity and neurochemistry, I am mapping the neural circuits that contribute to the social modulation of song (Matheson et al., Dev. Neurobiology, 2016). Of particular interest is the contribution of dopamine and norepinephrine to the social modulation of syllable structure, sequencing, and timing (e.g., Matheson and Sakata, Eur. J. Neurosci., 2015).

MECHANISMS UNDERLYING SEQUENCE LEARNING AND CONTROL 

Complex behaviors like birdsong consist of individual motor acts sequenced and timed in particular ways.  My lab is interested in revealing how brain activity in focal circuits regulates the learning and control of syllable sequencing and timing. We are characterizing and modelling the plasticity of syllable sequencing in juvenile and adult songbirds to gain insight into neurobiological mechanisms of sequence generation (e.g., James and Sakata, J. Neurophysiol., 2015; Matheson and Sakata, PLoS One, 2015; James et al., submitted).

We are also interested in revealing the mechanisms underlying biological predispositions in sequence learning in songbirds.  As for human speech and language, “universals” in the syntactic organization of song are observed in zebra finches, and we recently discovered that biological predispositions in sequence learning could underlie these universals in vocal sequencing (James and Sakata, Current Biology, 2017).  We are currently investigating the degree to which these learning biases are rooted in motor or auditory biases.  

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