(Eike Budinger)

In this project we are investigating various aspects of the general anatomy as well as connections of the auditory cortex, which are related to its anatomical delineation and parcellation into functional fields, to the processing of auditory and non-auditory stimuli (in particular to the lateralized processing of complex sounds) and to its involvement in learning-dependent plasticity.

By means of standard histological (e.g., Nissl-, Golgi-, Myelin-stains), sophisticated immunhistochemical and neuronal tract racing methods we recently described the cyto-, fiber- and chemoarchitecture of the auditory cortex and of the subcortical auditory pathway, the organization of its (tonotopic and non-tonotopic) cortical and subcortical connections and several anatomical asymmetries between the hemispheres.

The functional role of these connections in cortical, corticofugal and interhemispheric processing of complex stimuli is investigated in a combined approach of anatomical, physiological and behavioral techniques.

Figure: Comparison of the cyto- and fiberarchitecture (Golgi-stain) of the medial geniculate body (MG; gerbil), in particular of its fibrodendritic laminae (arrows), with the anterograde and retrograde labeling after an injection of a red-fluorescent tracer into the high-frequency and of a green-fluorescent tracer into the low-frequency representation area of the primary auditory cortex (field A1). The topographic labeling patterns suggest tonotopic (frequency-specific) connections between both structures.