Glomerular information processing in Xenopus laevis
von Daniëlle de Jong
Datum der mündl. Prüfung:2016-04-22
Betreuer:Prof. Dr. Dr. Detlev Schild
Gutachter:Prof. Dr. Walter Stühmer
Gutachter:Prof. Dr. Michael Müller
EnglischOlfactory glomeruli are structural and functional neuropils in the olfactory bulb. Although many olfactory receptor neurons (ORNs) project to one glomerulus, stimulusinduced responses within single glomeruli could not be previously distinguished using calcium imaging. At the level of the olfactory epithelium, however, activity differences within ORN subpopulations have been reported. I studied stimulus-induced and spontaneous activity patterns of intraglomerular ORN axons in order to obtain a deeper understanding of presynaptic odor representations within single glomeruli. Dose-response profiles and spontaneous activity patterns were obtained for glomeruli stained with CaGreen or JG205, which is a newly synthesized dye. From CaGreen-stained glomeruli odorant response profiles were acquired as well. Activity-specific information was then used to investigate how individual intraglomerular axons can be distinguished based on activity patterns. The presented data revealed, that, a combination of fast 3D line-illumination microscopy and activity correlation of spontaneous activity patterns was sufficient for the visualization of JG205-stained ORN axons. An activity-based separation of intraglomerular axons was, however, only partially possible for axons stained with CaGreen. The latter confirms previously reported results, namely, that response profiles and/or spontaneous activities from CaGreen-stained glomeruli cannot be assigned to individual CaGreen-stained axons (Wachowiak et al., 2004). The study of information processing within individual intraglomerular axons is essential for a deeper understanding of the presynaptic representation of odors. Visualizing and identifying individual intraglomerular axons simultaneously based on their activity patterns facilitates the study of presynaptic information processing. Furthermore, the combination of fast 3D calcium imaging and activity correlation imaging can also be used to investigate information processing in single neurons across brain areas and species.
Keywords: olfactory glomeruli; glomerular response profiles