The Polley Lab is interested in the mechanisms and therapeutic potential of brain plasticity. Brain plasticity (or neuroplasticity) is the science of brain change. Of all the organs in our body, the brain exhibits a unique capacity to change its anatomical, physiological and chemical composition according to

Research conducted in the past 50 years supports the view that the lifelong expression of plasticity in neocortex can be divided into two sequential stages: sensitive period plasticity and reinforcement-based plasticity. In infancy and childhood, experience can exert particularly profound effects on the structure and function of the brain during limited time windows called sensitive periods. Whereas passive experience with sound is sufficient to shape developing forebrain circuits, reorganization in the adult auditory forebrain carries the additional requirement that sound predicts behaviorally meaningful consequences (i.e. reward or punishment). This line of work uses a combination of genetic, pharmacological, neurophysiological and behavioral tools to identify factors that regulate the timing of sensitive periods and the mechanisms that distinguish sensitive period plasticity from reinforcement-based plasticity.

The underlying premise for this line of inquiry is that depriving the cochlea of normal patterned input will have profound impacts on the development of auditory forebrain circuits and that this neurophysiological plasticity will map onto predictable hearing deficits defined behaviorally. Studies of neurophysiological plasticity in the central auditory system following acute sensorineural hearing loss have made considerable progress towards characterizing the distributed pattern of reorganization across midbrain and forebrain auditory nuclei. In contrast, comparatively little is known about the effects of auditory deprivation via conductive hearing loss. Given that conductive hearing loss in the form of middle ear pathologies such as otitis media with effusion (OME) is the most commonly diagnosed illness among children in the United States, and has been repeatedly associated with lasting deficits in auditory processing, detailed studies describing the central neurophysiological consequences of conductive hearing loss are needed. By combining a method for reversible conductive hearing loss with techniques to characterize plasticity at the level of single neurons, representational maps and the behaving animal, the proposed studies introduce a promising approach to address basic research questions regarding experience-dependent plasticity and translational questions related to the pathophysiology of developmental hearing loss.

Daniel B. Polley is an Assistant Professor in the Department of Hearing and Speech Sciences at Vanderbilt University School of Medicine, a member of the Vanderbilt Kennedy Center for Research on Human Development, a member of Vanderbilt Brain Institute, a member of the Center for Integrative and Cognitive Neuroscience, a member of the Center for Molecular Neuroscience and is affiliated with the Department of Psychology.

our specific experiences with the surrounding world. The mechanisms that convert experience into lasting neural changes are at the root of our individuality and play an essential role in our ability to encode, recall, predict, learn and act in a fast-paced world.

We choose to study experience-dependent plasticity in auditory regions of the rodent thalamus and neocortex. Experience plays a vital role in

refining the basic patterns of connectivity in these forebrain regions and shapes how social animals from mice to men perceive environmental and communication sounds. Our lab seeks to elucidate the mechanisms of plasticity in auditory forebrain circuits through the combined application of in vivo extracellular recordings, auditory behavioral assays, neuropharmacology, computational models and genetic manipulations. Our overall goal is to understand how experience with sound shapes the organization of the auditory forebrain in early postnatal development and how remediation methods based on the science of brain plasticity might be used to correct the functional properties of aberrant brain circuits in later life.

Ongoing work in the lab is focused on two related questions: