(Holger Lison)

In this project we investigate the organizational principles of the cortical connections of the auditory cortex in Mongolian gerbils (Meriones unguiculatus). We want to evaluate, among others, which connections are organized in a parallel and which in a serial (hierarchical) fashion, whether they are ascending (i.e. feed-foreward, bottom-up, stimulus-driven) or descending (i.e. feed-back, top-down, task-specific), and whether they act excitatory or inhibitory. In order to approach these issues we (1) trace the connections of the known auditory fields by means of the anterograde and retrograde transport of various neuronal tracers, and (2) try to characterize the functional role of different neurotransmitters on these connections using immunohistochemical double-staining methods.

Fig.: GABAergic inhibitory interneuron in the auditory cortex which is immunopositive for the calcium-binding protein parvalbumin (bluish staining). This cell is contacted by the (probably excitatory acting) axon collaterals of a more distant pyramidal cell (brownish staining, arrows).