How One Part of the Body Knows What the Other Does

Gaëtan Lepreux and Volker Dürr investigate what an insect’s antenna tells the forelegs in a CITEC research project

How does the antenna of an insect transmit information to the legs? Gaëtan Lepreux and Professor Dr. Volker Dürr are tackling this question in their research project titled “Monitoring real-time world interaction in an identified neuron.” To do this, they are investigating how neurons convey the sensory information gathered by an insect’s antenna from the brain to the ventral nerve cord. In insects, the ventral nerve cord the part of their nervous system that controls muscle contractions, and thus motion – similar to what the spinal cord does in humans.

“Monitoring real-time real-world interaction in an identified neuron” is one of five small “high-risk” research projects at CITEC. Photo: J. Ache, CITEC/Biological Cybernetics “The neurons in the brain that transmit the information from the antennae to the movement-generating apparatus of the insect are what we call descending neurons,” says Professor Dr. Volker Dürr, a member of the Biocybernetics group at CITEC. “What interests us here is what kind of information is transmitted. How is information from different sensory organs encoded and integrated for the purpose of target-oriented motor control? How does self-movement of the insect affect information transfer?”

Recently, CITEC researchers Dr. Jan Ache (now at the Janelia Research Campus in Virginia, USA) and Dr. Stephan Haupt (now at Tokyo University, Japan) identified and characterized some of these descending neurons in this research project. Normally, the neuron has to be impaled by use of a very fine electrode in order to precisely measure its electrical impulse. This, however, is not necessary for the neuron cONv (the neoron shown in the image): the researchers can detect impulses of the cONv neuron among many hundreds of signals in the ventral nerve cord. And they can even do this while the animal is moving.

Gaëtan Lepreux, a member of the Biocybernetics group, is pursuing this topic in his PhD project: he is studying descending neurons in an electrophysiology lab, where the electrical activity of neurons is recorded with electrodes. Measuring instruments amplify the measured currents of the neurons, record and chart them. Due to the small size of the neurons, the measurement takes place under a microscope. So-called micro-manipulators are used to position the electrodes. The researchers also record the movement of the antennae with a special camera.

The lab is currently getting a new addition: a “spherical treadmill” on which the insect can walk on while its neuronal activity is being recorded. The insect walks stationarily on a "ball” that floats on an air cushion. The air cushion allows the insect to turn the ball underneath it during walking. “Thanks to our new tradmill, in the future, we will be able to measure how quickly and in which direction the insect is going, and how the neuronal activity changes,” says Gaëtan Lepreux.

Some results of this project have already been used to develop a software model that maps the characteristics of various descending neurons. The model explains, for instance, how the characteristic activity patterns of the descending neurons follow the movement of the antennae. Recent findings indicate that the activity of the neurons during active self-motion is quite distinct from passive movement of the antenna. Here, the researchers are investigating how the information transfer in the nervous system is adjusted during active interaction of the animal within its environment.

In this project line, researchers deal with particularly innovative and original topics with some uncertainty about the immediate outcome. In addition to these rather small, “high-risk” projects, there are also four large-scale research projects and eight interdisciplinary research projects. Beyond these projects, researchers from the Graduate School conduct research on their own innovative individual projects.

More information is available online at:
Project website: https://cit-ec.de/de/monitoring-real-time-real-world-interaction-identified-neuron

Contact:
Prof. Dr. Volker Dürr, Bielefeld University
Cluster of Excellence Cognitive Interaction Technology (CITEC)
Telephone: 0521 106-5528
Email: volker.duerr@uni-bielefeld.de