Exploring the fly's neural code

• Grant number: 02/03565-4
• Support Opportunities: Research Projects - Thematic Grants
• Start date: December 01, 2002
• End date: December 31, 2008
• Field of knowledge: Physical Sciences and Mathematics - Physics - Classical Areas of Phenomenology and Applications
• Principal Investigator: Roland Koberle
• Grantee: Roland Koberle
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The aim of the present research project is to study the response of the motion sensitive neuron H1 in the lobula plate of flies, order Diptera, gentis Chrysomia, to visual stimuli. The data obtained are subjected to analysis with the aim to understand the encoding and the decoding properties of the neuron with special attention to adaptation dependent strategies employed by the fly. H1 being a spiking neuron, we record extracellularly from the live, immobilized fly with a Tungsten electrode and register the spike arrival times in synchrony with the stimulus, represented by a visual scene moving rigidly in the horizontal direction. The same scheme can be applied to neurons like V2, sensitive to movement in the vertical direction. Equipment is being completed to record simultaneously from neurons in the right and left lobula plate and from horizontally and vertically sensitive neurons. At present stimuli are displayed on a Tektronix 605 Monitor with refresh rate of 500 Hz. But our project includes support to project naturalistic stimuli, like transparencies of sceneries the fly might encounter in her natural environment, these being subjected to a translational velocity generated by the experimenter. The lab's activity may be divided into: building equipment for new experiments, actually doing these and subsequently analyzing the data obtainded. As far as the electronics is concerned, the TIO-10 National Instrument board will have to be replaced by dedicated hardware. This will also allow the simultaneous generation and monitoring of the stimulus, besides enabling us to control of the stimulus in real time, on the fly so to speak. The mechanical micromanipulators will have to be duplicatedj/adapted to allow simultaneaous access to both hemispheres of the fly's brain. The data analysis relies on established methods [3] [4] [5] for measureing the information conveyed by the spike train about the stimulus, characterizing the time scales involved and the strategies used by the fly to maneuver in a highly varying environment, which we simulate through a dynamically varying probability distribution for the stimuli. (AU)