The secrets of visual navigation

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The circuit diagram of the nervous system of the fruit fly Drosophila melanogast
The circuit diagram of the nervous system of the fruit fly Drosophila melanogaster was the focus of the study. Image source: Tyler Sloan and Amy Sterling for FlyWire, Princeton University

A new study reveals groundbreaking findings on visual navigation in the brain of the fruit fly Drosophila melanogaster

An international research team from Freie Universität Berlin and the University of California Santa Barbara has conducted the first systematic analysis of all synaptic connections in the brain of an adult animal in a groundbreaking study. The study focused on the connectome - the wiring diagram of the nervous system - of the fruit fly Drosophila melanogaster. The study, entitled "Connectomic reconstruction predicts visual features used for navigation" and published in a special issue of the renowned journal Nature, sheds light in particular on the neuronal networks that underlie visual navigation (link to study ’024 -07967-z ).

The research team led by Mathias Wernet (Freie Universität Berlin) and Sung Soo Kim (University of California, Santa Barbara) was able to show that at least ten parallel synaptic pathways exist in the brain of the fruit fly that process visual information on its way to the central brain. "This is a remarkable finding that shows that even the brain of such a small organism has amazingly complex visual processing mechanisms," says Mathias Wernet, Professor of Neural Networks.

In their research work, the scientists used electron microscopy data to reconstruct over 5,000 nerve cells of the fruit fly Drosophila melanogaster, including their chemical synapses. The three first authors, doctoral student Emil Kind from Berlin and doctoral students Jennifer Yuet Ha Lai and Dustin Garner (both from California) have thus succeeded in creating the first complete representation of all visual inputs to the central complex. The central complex is an evolutionarily conserved structure in the central brain of insects that plays an important role in the development of navigational decisions.

"The results of this groundbreaking work allow conclusions to be drawn about the nature of the visual stimuli processed and the functional properties of the nerve cells involved," explains Mathias Wernet. The international research team also succeeded in experimentally confirming some of these scientific predictions using in vivo 2-photon microscopy.

In the same "Nature" special issue, the study "Connectomic reconstruction predicts visual features used for navigation" is complemented by a second publication in collaboration with the authors Professor Sebastian Seung and Mala Murthy from Princeton University entitled "Neuronal parts list and wiring diagram for a visual system" ( ’024 -07981-1 ). This provides an in-depth analysis of the neuronal components and wiring patterns of the fruit fly’s visual system.

The findings from both studies provide a crucial basis for future research. "In the future, these connectomic data will serve as an important foundation for the planning and interpretation of physiological work or behavioral experiments with the aim of better understanding navigation decisions," says Mathias Wernet. (cxm)