CRG: Cracking the function of the fly olfactory system to understand how neural circuits work

CRG: Cracking the function of the fly olfactory system to understand how neural circuits work

News from CRG

If a banana is rotting in the fruit basket of your kitchen, chances are that a fruit fly will find it long before you do. How is the nervous system of a tiny fly capable of ascending the odour trail created by a banana? This question has been addressed in a new study conducted by the Sensory Systems and Behaviour laboratory led by Matthieu Louis at the EMBL-CRG Systems Biology Unit of the CRG. The fruit fly Drosophila melanogaster is an excellent model system to explore how complex behaviours, such as chemotaxis, are controlled by the activity of neural circuits. Although the word neuroscience may evoke the human brain to most of us, research in smaller genetic model organisms often represents the most direct entry point into the molecular and cellular basis neural functions.

The research carried out by the Louis lab is a new example on how the combination of interdisciplinary tools permits to probe basic principles underlying complex biological processes. In this case, CRG scientists dive deep into the fruit fly neural circuits, which could be the entrance to more complex systems as the human brain.

To identify the neural circuits involved in chemotaxis, the team decided to concentrate on the fruit fly larva, which comprises 10,000 neurons — 10 times less than adult flies and 10 million times less than humans. In temerarious efforts, the team screened over 1,100 fly strains where the function of a small subset of neurons of the brain could be genetically turned off. “At the beginning of this project, we had the feeling to be looking for a needle in a haystack. We knew about the 21 olfactory neurons in the head of the larva and the motor neurons in the equivalent of spinal cord in the larva. In contrast, we had virtually no clue about the identity of the neurons in between, the synapses responsible for the processing of the olfactory information and its conversion into navigational decisions”, explains Matthieu Louis.

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Tastekin et al. "Role of the subesophageal zone in sensorimotor control of orientation in Drosophila larva". Current Biology (2015). June 1 2015.

Schleyer et al. “The impact of odor-reward memory on chemotaxis in larval Drosophila” Learning & Memory (2015).