Mechanisms and functional consequences of the regulation of visual motion processing by a neuromodulator in the fly brain

• Applicant: Dr. Roland Kern, since 9/2015
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 233302803

Many animals show frequent transitions between different states of locomotor activity. Visual motion input differs profoundly between these states, in particular for rapidly flying animals like blowflies. In the fly brain the gain and the velocity dependence of visual motion-sensitive neurons were shown to depend on the locomotor state. Larger responses and higher velocity optima were present during walking or flying than during rest. Similar effects were also shown to be evoked by application of an agonist of the neuromodulator octopamine, indicating that state-dependent gain adjustments in the visual system are mediated by octopaminergic efferents. In the planned project, the mechanisms and the functional consequences of this modulation will be investigated. (1) By performing intracellular recordings from visual motion-sensitive neurons we will test the effects of octopamine on cellular properties. Changes in membrane potential, input resistance and synaptic currents will be evaluated to characterize cell-intrinsic sensitivity modulation by octopamine as well as its impact on presynaptic input layers. (2) The functional relevance of state-dependence for the processing of behaviorally relevant stimuli will be assessed. We will analyze the impact of octopamine on the neuronal representation of naturalistic visual stimuli reconstructed from the flies' movement trajectories recorded in a flight arena. (3) To examine whether the modulation of brain activity by octopamine affects behavioral choices we will test whether steering responses during tethered flight are biased by unilateral manipulation of octopamine signaling.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Dr. Rafael Kurtz, until 9/2015