Neurogenetic Analysis of a Visual Working Memory in Drosophila melanogaster

• Applicant: Professor Dr. Roland H. Strauß
• Subject Area: Cognitive, Systems and Behavioural Neurobiology ; Animal Physiology and Biochemistry ; Sensory and Behavioural Biology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 256782602

Apart from simple reflexes adaptive behavior of animals is not imaginable without their ability to remember external stimuli, own actions and the consequences thereof. Insects employ different strategies during an excursion in order to find back to a nest or just their starting point. For instance, the own position can be stored in relation to a point of reference and updated idiothetically in cases where a landmark gets out of view. Indeed, we have identified such a working memory for visual orientation in the genetic model organism Drosophila melanogaster. Analysis of the brain structure mutant ellipsoid-body open (ebo) led us to the ellipsoid body in the central brain of Drosophila as the relevant structure for the orientation memory. Molecular analysis of the ebo mutant showed that the Drosophila ortholog of the transcription activator Serum Response Faktor (dSRF) is essential for a functional working memory in the adult ellipsoid body. Moreover, the cGMP regulated protein kinase (PKG) encoded by foraging and the S6 Kinase II (RSK2) encoded by ignorant are both essential in a common pathway in the ring neurons of the Drosophila ellipsoid body. Genetic interaction studies indicate that foraging PKG positively regulates the activity of the ignorant kinase. It is the goal of this grant application to understand the visual orientation memory of Drosophila in detail using genetic and neuroanatomical methods as well as behavioral physiology. We aim to unravel the complete signal transduction pathway in which both protein kinases act together. First results indicate that the transcription activator CREB (cAMP responsive element binding protein) and its target genes form the endpoint of this pathway. The respective gene expression seems inevitable for the neurons to be able to hold this memory of just a few seconds; its transient substrate remains to be identified. In addition, we aim to understand the interaction between the transcription factor dSRF and the PKG-RSK2 signaling pathway. The overarching goal is to unravel the fundamental molecular mechanisms of learning and particularly those of a short-lived working memory, required to establish an orientation memory from acute visual information. We expect to find, at least in part, novel and alternative principles and signaling pathways as compared to those governing olfactory conditioning with its short-, middle-, and long-term memory forms.

• DFG Programme: Research Grants
• Participating Person: Dr. Burkhard Poeck