Brinkmann, Alexander Peter Ernst

English

The olfactory system is renowned for its ability to sample and process a tremendously
large odorant space. Lately, it has been shown that other sensory qualities
such as temperature and pressure are detected in the olfactory system. However,
little is known about how they are processed within the olfactory bulb and how this
multisensory information is integrated in the context of olfaction.
In this thesis, two specific olfactory glomeruli — the mechanosensitive beta- and the
thermosensitive gamma
-glomerulus — in the olfactory bulb of Xenopus laevis tadpoles
were analyzed by means of a custom-built line illumination microscope. The line
illumination technique was combined with subtraction imaging and pixel reassignment
to perform fast calcium recordings in three dimensions. These recordings,
covering first- and second-order neurons in the olfactory bulb, revealed a strong
interconnection of both sensitivity to temperature drops as well as mechanosensitivity
with olfaction. Dual-sensitive mitral/tufted cells responding to amino acids as
well as to temperature drops were located in the proximity of the 
-glomerulus. A
dose-response curve for the mechanosensitivity of the beta-glomerulus was measured.
Additionally, the same glomerulus showed sensitivity to a surprisingly broad spectrum
of single amino acids, thereby combining mechano- and chemosensitivity in the
same structure. The axon separation of different olfactory receptor neurons within
a single glomerulus was successful using double staining electroporation. Recordings
obtained from such stainings suggest that the sensitivity of the beta-glomerulus
to amino acids was caused by a single broadly tuned olfactory receptor. Lastly, a
sufficient resolution for single axon as well as for single dendrite recordings within
the beta-glomerulus was achieved by line illumination microscopy. The demonstrated
increase in efficiency of the line scanning technique enables future experiments with
two calcium indicators to analyze the signal transmission within a single glomerulus

Georg-August-University Göttingen

Processing of different sensory qualities in the olfactory bulb of Xenopus laevis studied by advanced line illumination microscopy

https://ediss.uni-goettingen.de/bitstream/11858/00-1735-0000-002B-7C18-F/1/Dissertation_AlexanderBrinkmann.pdf

Processing of different sensory qualities in the olfactory bulb of Xenopus laevis studied by advanced line illumination microscopy

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Georg-August-University Göttingen