Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A backup copy in the central brain: How fruit flies form orientation memory

07.03.2017

Gaseous neurotransmitters play an important role in the short-term orientation memory of Drosophila / Scientist decode biochemical processes

Insects have a spatial orientation memory that helps them remember the location of their destination if they are briefly deflected from their route. Researchers at Johannes Gutenberg University Mainz (JGU) have examined how this working memory functions on the biochemical level in the case of Drosophila melanogaster.


A small group of ring-shaped neurons (green) in the central brain of the fly (magenta) are the seat of visual orientation memory

photo/©: AG Strauss, JGU


A small group of ring-shaped neurons (green) in the ellipsoid body of the fly (magenta in the center of the image) are the seat of visual orientation memory. The scale bar shown at the bottom right of the image is equivalent to 25 micrometers (µm) in length

photo/©: AG Strauss, JGU

They have identified two gaseous messenger substances that play an important role in signal transmission in the nerve cells, i.e., nitric oxide and hydrogen sulfide. The short-term working memory is stored with the help of the messenger substances in a small group of ring-shaped neurons in the ellipsoid body in the central brain of Drosophila.

Flies form a memory of locations they are heading for. This memory is retained for approximately four seconds. This means that if a fly, for instance, deviates from its route for about a second, it can still return to its original direction of travel.

"This recall function represents the key that enables us to investigate the biochemistry of working memory," said Professor Roland Strauss of JGU's Institute of Developmental Biology and Neurobiology. The researchers are particularly interested in learning how a network in an insect's brain can build such an orientation memory and how exactly the related biochemical processes function.

Working on her doctoral thesis, Dr. Sara Kuntz found to her surprise that there are two gaseous neurotransmitters that are involved in information transmission. These gaseous messenger substances do not follow the normal route of signal transmission via the synaptic cleft but can diffuse directly across the membrane of neighboring nerve cells without docking to receptors.

It was already known that, for the purposes of memory formation, nitric oxide (NO) is essential for the feedback of information between two nerve cells. What has now emerged is that NO also acts as a secondary messenger substance in connection with the amplification of the output signals of neurons.

This function of nitric oxide can apparently also be assumed by hydrogen sulfide (H2S). Although researchers were aware that this gas plays a role in the control of blood pressure, they had no idea that it had another function in the nervous system. "It has long been assumed that hydrogen sulfide was harmful to the nervous system. But the results of our research show that it is also of importance as a secondary messenger substance," explained Strauss. "We were absolutely astonished to discover that there are two gaseous neurotransmitters that are important to memory."

Biochemical signal transduction pathway for visual working memory

Strauss and his colleagues postulate that both neurotransmitters together with cyclic guanosine monophosphate (cGMP) form the perfect storage media for short-term memories. They presume the process functions as follows: The fruit fly sees an orientation point and moves in its direction, at which point nitric oxide is formed. The nitric oxide stimulates an enzyme that then synthesizes cGMP. Either the nitric oxide itself or cGMP accumulate in a segment of the doughnut-shaped ellipsoid body that corresponds to the original direction taken by the fly.

The ellipsoid body is located in the central complex of the insect brain and is divided into 16 segments, rather like slices of cake, each of which represents a particular spatial orientation. Given that a Drosophila fly deviates from its path because it loses sight of its initial orientation point and temporarily becomes aware of another, that fly is then able to get back on its original course because a relatively large quantity of NO or cGMP has accumulated in the corresponding ellipsoid body segment.

However, all of this only functions under one condition. The memory is only called up if the fly does not see anything in the interim, the fly must also lose sight of the second orientation point. "The recall function only becomes relevant when there is nothing more to see and readily acts as an orientation aid for periods of up to four seconds," explained Dr. Sara Kuntz, primary author of the study, adding that this seemingly short time span of four seconds is perfectly adequate to enable a fly to deal with such a problem. "The ellipsoid body retains the backup copy to span any such brief interruptions." There is no point in having a working memory with a longer duration as objects that have been selected as orientation points are not necessarily anchored in place but may themselves also move.

Images:
http://www.uni-mainz.de/bilder_presse/10_drosophila_gedaechtnis_ort_01.jpg
A small group of ring-shaped neurons (green) in the central brain of the fly (magenta) are the seat of visual orientation memory
photo/©: AG Strauss, JGU

http://www.uni-mainz.de/bilder_presse/10_drosophila_gedaechtnis_ort_02.jpg
A small group of ring-shaped neurons (green) in the ellipsoid body of the fly (magenta in the center of the image) are the seat of visual orientation memory. The scale bar shown at the bottom right of the image is equivalent to 25 micrometers (µm) in length
photo/©: AG Strauss, JGU

Publication:
Sara Kuntz, Burkhard Poeck, Roland Strauss
Visual Working Memory Requires Permissive and Instructive NO/cGMP Signaling at Presynapses in the Drosophila Central Brain
Current Biology, 16 February 2017
DOI: 10.1016/j.cub2016.12.056

Further information:
Prof. Dr. Roland Strauss
Institute of Developmental Biology and Neurobiology
Johannes Gutenberg University Mainz
55099 Mainz, GERMANY
phone +49 6131 39-25034
fax +49 6131 39-25443
e-mail: rstrauss@uni-mainz.de
http://www.bio.uni-mainz.de/zoo/abt3/307.php

Weitere Informationen:

http://www.cell.com/current-biology/abstract/S0960-9822(16)31538-X – Article in Current Biology ;
http://www.bio.uni-mainz.de/zoo/abt3/269.php – Visual Orientation Behavior research at JGU ;
http://www.uni-mainz.de/presse/12513_ENG_HTML.php – Press release "Even fruit flies have an orientation memory: Recall tested in a virtual space", 3 June 2008

Petra Giegerich | idw - Informationsdienst Wissenschaft

More articles from Life Sciences:

nachricht Kidney tumor: Genetic trigger discovered
18.06.2018 | Julius-Maximilians-Universität Würzburg

nachricht New type of photosynthesis discovered
18.06.2018 | Imperial College London

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Novel method for investigating pore geometry in rocks

18.06.2018 | Earth Sciences

Diamond watch components

18.06.2018 | Process Engineering

New type of photosynthesis discovered

18.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>