Current Topics of Research

By combining physiological, neuroanatomical, and computational approaches we attempt to provide a better understanding of the cortical processing of complex sounds with the.  long-term goals to develop behavioral and technological rehabilitation strategies to compensate or correct for the consequences of peripheral hearing loss as well as to optimize design and implementation of auditory prostheses in the profoundly deaf patient.

Michael M. Merzenich, PhD,  addresses in his research a wide range of issues surrounding questions of  the consequences of  maturation and aging on the ability of auditory cortex to process speech  sounds. Among the questions that are currently addressed are:

How does expectation bias cortical representations of sequent (syntactic) acoustic inputs?  By what mechanisms does sensory feedback bias cortical representations of expected sound  sequences?

How is closure of the maturational critical period regulated in the auditory/aural speech cortex?

How does temporal processing of acoustic inputs change as we age? 

How can we quickly reverse abnormal cortical processing that arises as a function of impoverished language exposure or from inherited sources of high noise in early infancy, by behavioral training applied in older children and in adults? 

What are the contributions of different neuromodulatory systems  - such as serotonin, dopamine and neuroadrenaline – in the regulation of cortical plasticity and in models of autism and other brain dysfunctions?

Steven Cheung, MD, focuses some of his scientific efforts on translational research, such as complex medical decision making using conjoint analysis tools applied to acoustic tumor treatment outcomes. Clinically oriented research goals include developing methods for tinnitus suppression and brain imaging analysis of auditory processing deficits in subjects with altered voicing. His basic research efforts are directed at recordings from auditory cortex in animals with altered vocal apparatuses, and consequences for auditory cortex organization for subjects with peripheral hearing losses.

Christoph Schreiner, PhD, MD, focuses his research on the understanding of the functional organization of central auditory stations of the mammalian brain (mainly the thalaus and auditory cortex) for the encoding of complex auditory signals – such as speech and communication signals – in normal and hearing-impaired models. He approaches this topic by using electrophysiology of single neurons in the context of broader topographic organizations and combines this with studies of the neuroanatomy of central auditory stations.  The encoding of complex sounds in the central auditory system of mammals assesses the effects of speaker-dependent signal categorization.  The goal is to determine where and how an acoustic-based sound representation is transformed into a speaker-independent, object-based representation of the auditory environment. The lamina-specific functional organization of auditory cortex of behaviorally relevant aspects (e.g. frequency resolution, discrimination of vowel-like signals) is studied in awake, behaving animals and in models of linear-nonlinear receptive fields. The nature of information transmission and transformation is explored within and between different functional modules in auditory cortex. Intracellular investigations of cortical receptive field generation and plasticity with whole-cell recordings have revealed fundamental insights into the construction of cortical receptive fields and the mechanisms that regulate their plasticity. The goal is to dissect the cellular and network contributions to functional organization and plasticity in the developing and adult animal.