Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN Sonderseminar

Tuesday, 28.03.2006 16:30 s.t.

A calcium imaging study of the representation of odour identity and intensity in the antennal lobe of the ant Camponotus floridanus

by Jakob Neef
from Department of Behavioral Physiology and Sociobiology, Universität Würzburg

Contact person: Fred Wolf

Location

Seminarraum Haus 2, 4. Stock (Bunsenstr.)

Abstract

Insects receive odours by odorant receptor cells located on their antennae. The olfactory information is subsequently relayed via the antennal nerve to the antennal lobes, the primary olfactory neuropil in the insect brain. The antennal lobes are organized in spherical subunits, the glomeruli, inside which an extensive processing of the incoming information takes place before it is forwarded to the higher order brain centres. In the course of this diploma thesis the technique of calcium imaging was successfully applied to visualize neural activity in vivo in the florida carpenter ant Camponotus floridanus. Selective staining of projection neurons in the antennal lobe of Camponotus floridanus with a calcium sensitive dye allowed to address the question of how odour quality and intensity are represented in this neuropil. It was shown that odour presentation evokes odour specific activity patterns in the antennal lobe with great similarity across individuals. The glomeruli were identified as the source of these patterns since size and position of activated areas coincide with size and location of glomeruli visible in the antennal lobe. Therefore, individual odours are represented by the activity of distinct sets of glomeruli. Odours presented to the animal at high concentrations from ranging from 10-4 to 10-1 evoked activity patterns in which a large number of glomeruli is strongly activated while the same odours presented at lower concentrations of 10-9 to 10-6 activated a lower number of glomeruli with lower intensity. The activity pattern evoked by low odour concentrations ranging from 10-9 to 10-6 was constant in intensity and number of activated glomeruli for all tested concentrations. The results of this study show in part good conformance with published results for the olfactory system of the honeybee. However, it seems that differences between ants and bees exist in the temporal structure of an odour response and in the representation of odour intensities in projection neurons.

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