Daniel B. Polley, Ph.D.

Harvard Medical School

Associate Professor of Otolaryngology

Massachusetts Eye and Ear

Amelia Peabody Neural Plasticity Unit
Associate Scientist

Research Summary

Research Area Affiliations

Research Summary

Research efforts in the Polley Lab are directed towards understanding the mechanisms and clinical implications of brain plasticity. Auditory brain plasticity exhibits a fundamental duality, a yin and yang, in that it is both a source and possible solution for various types of hearing impairments. Following cochlear afferent loss, the balance of excitation and inhibition tips toward hyperexcitability throughout auditory processing regions of the brain, increasing the "central gain" on afferent signals so as to partially compensate for a diminished input from the auditory periphery. Our work has shown that central gain cannot fully compensate for the loss of cochlear afferent neurons. To the contrary, by increasing spontaneous rates and correlated activity while decreasing the dynamic range of central coding, excess central gain can further distort the neural representation of complex communication sounds, such as speech in noise, and even induce the perception of phantom sounds, contributing to pathophysiological processes such as hyperacusis and tinnitus. This is the "yin," the dark side of brain plasticity, wherein the transcriptional, physiological, and neurochemical changes that compensate for the loss or degradation of peripheral input can incur debilitating perceptual costs. We are also committed to understand the "yang" of brain plasticity, how the remarkable malleability of the adult brain can be harnessed and directed towards an adaptive—or even therapeutic—endpoint through pharmacology, direct brain stimulation, and non-invasive approaches such as immersive sensory training. 

In the Polley Lab, our ultimate interests lie at the intersection of these two sides of brain plasticity; we are working to identify interventions that will turn down excess central gain, correct distorted map topography, and restore normal auditory perception in individuals with hearing loss. The Polley Lab pursues its research interests in animal models and human subjects. Our work in animal models leverages cutting-edge approaches in optogenetics, in vivo cellular imaging, multi-channel electrophysiology, and behavioral neuroscience to manipulate neuromodulatory systems, identify drug targets, and develop auditory training strategies that might shed light on human auditory pathologies. Our work in human subjects focuses on using customized auditory training interfaces to enhance speech processing in noise and reduce the subjective intensity of tinnitus.

Select Publications

Persistent thalamic sound processing despite profound cochlear denervation. Chambers AR, Salazar JJ, Polley DB. Frontiers in Neural Circuits. 2016;10:1-13.

Central gain restores auditory processing following near-complete cochlear denervation. Chambers AR, Resnik J, Yuan Y, Whitton JP, Edge AS, Liberman MC, Polley DB. Neuron. 2016;89:867-879.

Immersive audiomotor game play enhances neural and perceptual salience of weak signals in noise. Whitton JP, Hancock KE, Polley DB. Proc Natl Acad Sci U S A. 2014;111(25):2606-15.

View a complete list of peer-reviewed publications »