Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Feel-good hormone helps to jog the memory

08.11.2012
Press Release from the German Center for Neurodegenerative Diseases and the University of Magdeburg

The feel-good hormone dopamine improves long-term memory. This is the finding of a team lead by Emrah Düzel, neuroscientist at the German Center for Neurodegenerative Diseases (DZNE) and the University of Magdeburg.

The researchers investigated test subjects ranging in age from 65 to 75 years, who were given a precursor of dopamine. Treated subjects performed better in a memory test than a comparison group, who had taken a placebo.

The study provides new insights into the formation of long lasting memories and also has implications for understanding why memories fade more rapidly following the onset of Alzheimer’s disease. The results appear in the “Journal of Neuroscience”.

Dopamine is a multi-faced neurotransmitter. It provides communication between nerve cells as well as between nerve and muscle cells. If this signal transmission becomes disturbed, the consequences can be dramatic. This is illustrated by Parkinson’s disease, whose symptoms – akinesia and other movement disorders – can be traced back to a lack of dopamine. On the other hand, when someone is pleased or motivated, a flood of dopamine is released in the brain, which is why the term “feel-good hormone“ has become popular.

There have already been indications of the special role of dopamine in forming long-lasting memories for some time. The signs came from various studies and also from the fact that rewarding incidents and other important events can usually be remembered for a long time. Researchers led by Düzel, who is also affiliated with University College London, have now been able to confirm this effect in older people.

“Our investigations for the first time prove that dopamine has an effect on episodic memory. This is the part of long-term memory, which allows us to recall actual events. Occurrences in which we were personally involved,“ Düzel says. The Site Speaker of the DZNE in Magdeburg and Director of the Institute of Cognitive Neurology and Dementia Research at the University of Magdeburg adds: “Episodic memory is that part of our capacity to remember, which is first affected in Alzheimer’s dementia. This is why our results can contribute to a better understanding of the disease.“

Recognising pictures

In particular animal studies have indicated that to store experiences permanently the brain has to release dopamine. Düzel and his colleagues examined whether this also applies to humans: the task of the test subjects ranging in age from 65 to 75 years was to recognise photos which they had been shown previously. Half of the test participants had first taken a placebo and the remainder had taken Levodopa. This substance, also known as L-DOPA, is able to reach the brain from the bloodstream, and there it is converted into dopamine. In this way the researchers could exercise a targeted influence over dopamine levels in the brains of the test subjects. “Neurons, which produce dopamine, decline with age,“ Düzel says. “Increasing dopamine levels in these elderly subjects, should show a clear effect.“ The neuroscientist mentions another reason for undertaking the study with older people: „In old age the episodic memory declines. This is why the topic we are investigating is particularly relevant for elderly people.“

The participants were first shown black and white photos of indoor scenes and landscapes. They were to differentiate these images from others, which they had not seen before. When they first viewed the pictures brain activity of the participants was monitored using fMRT, a special form of magnetic resonance tomography. The photos which triggered hardly any activity in the memory centre were of particular interest to the neuroscientists. The reason: If this brain area is only slightly active, then it should cause little or no dopamine release. “In such cases the memory of these pictures should gradually fade. As they have been encoded only weakly,“ Düzel says, “we wanted to find out whether the memory of these pictures could nevertheless persist.“

Effect after six hours

Two and six hours after the participants had memorized the photos, they were requested to recognise and distinguish them from new images.

In the test after two hours there was no significant difference between participants who had taken Levodopa and those who had consumed a placebo. However, after six hours memory performance changed. Test subjects with Levodopa recognised up to 20 per cent more photos than the members of the comparison group. The ratio between the amount of Levodopa taken and the body weight of the test subjects proved to be decisive for an optimal dose. “This confirms our assumption that dopamine contributes to anchoring memories in the brain on a permanent basis. You might say it improves the survival chances of memory content,“ Düzel indicates. “Our study also shows that the survival of memories can be regulated, regardless of how strong these were originally encoded. This is a new finding.“

But why did the effect emerge only after six hours? Düzel sees the cause in the way in which the brain stores memories. “When memories are encoded, certain changes take place at the nerve endings, the so-called synapses,“ he explains. “This activation is however only temporary, and afterwards the state of synapses change back again. This is unless dopamine is available so that newly formed synapses can be stabilised over a long period of time.“ The test after two hours must still have taken place during the period of short-term synaptic activation, according to the neuroscientist. Both test subject groups therefore had similarly good results. However, at the later time the memories of the test participants with the placebo had already started to fade. Now, the influence of the dopamine was noticeable for the other test subjects.

Future outlook

In this study participants had taken the dopamine precursor before memorizing. The finding that the persistence of memories can be influenced – independent of whether memory encoding was weak or strong – might open the way to further investigation. “It is conceivable that participants might receive the supplement at a later stage,“ Düzel says. “The idea is that they learn something, then take dopamine afterwards and still don’t forget what they have learnt.“

In addition, the study gives food for thought for the treatment of Alzheimer’s dementia. “The episodic memory suffers substantially when affected by Alzheimer’s. Our results show that in addition to current forms of treatment, which chiefly target certain protein deposits in the brain, other aspects should also be taken into consideration“, Düzel says. “Here dopamine and the so-called neuromodulatory systems, which release chemical messengers into the brain are of particular importance. But so far, research into this topic is still in its infancy.“

Original publication:
“Dopamine Modulates Episodic Memory Persistence in Old Age“, Rumana Chowdhury, Marc Guitart-Masip, Nico Bunzeck, Raymond J. Dolan, and Emrah Düzel, The Journal of Neuroscience, online at: http://www.jneurosci.org/content/32/41/14193

The German Center for Neurodegenerative Diseases (DZNE) investigates the causes of diseases of the nervous system and develops strategies for prevention, treatment and care. It is an institution of the Helmholtz Association with sites in Berlin, Bonn, Dresden, Göttingen, Magdeburg, Munich, Rostock/Greifswald, Tübingen and Witten. The DZNE cooperates closely with universities, their clinics and other research facilities. Co-operation partners in Magdeburg are the Otto-von-Guericke University, the University Clinic and the Leibniz-Institute for Neurobiology. Website: http://www.dzne.de

Contacts
Prof. Dr. Emrah Düzel
Deutsches Zentrum für Neurodegenerative Erkrankungen &
University of Magdeburg (Germany)
Tel.: + 49 391 6117 520
Dr. Dirk Förger
Head of Press and Public Relations
Deutsches Zentrum für Neurodegenerative Erkrankungen, Bonn (Germany)
Tel.: + 49 228 43302 260
dirk.foerger@dzne.de
Kornelia Preuß-Suske
Public Relations
University of Magdeburg (Germany)
Medizinische Fakultät
Tel.: + 49 391 67 15162
kornelia.suske@med.ovgu.de

Marcus Neitzert | idw
Further information:
http://www.dzne.de
http://www.jneurosci.org/content/32/41/14193

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
21.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Topologische Quantenzustände einfach aufspüren

Durch gezieltes Aufheizen von Quantenmaterie können exotische Materiezustände aufgespürt werden. Zu diesem überraschenden Ergebnis kommen Theoretische Physiker um Nathan Goldman (Brüssel) und Peter Zoller (Innsbruck) in einer aktuellen Arbeit im Fachmagazin Science Advances. Sie liefern damit ein universell einsetzbares Werkzeug für die Suche nach topologischen Quantenzuständen.

In der Physik existieren gewisse Größen nur als ganzzahlige Vielfache elementarer und unteilbarer Bestandteile. Wie das antike Konzept des Atoms bezeugt, ist...

Im Focus: Unterwasserroboter soll nach einem Jahr in der arktischen Tiefsee auftauchen

Am Dienstag, den 22. August wird das Forschungsschiff Polarstern im norwegischen Tromsø zu einer besonderen Expedition in die Arktis starten: Der autonome Unterwasserroboter TRAMPER soll nach einem Jahr Einsatzzeit am arktischen Tiefseeboden auftauchen. Dieses Gerät und weitere robotische Systeme, die Tiefsee- und Weltraumforscher im Rahmen der Helmholtz-Allianz ROBEX gemeinsam entwickelt haben, werden nun knapp drei Wochen lang unter Realbedingungen getestet. ROBEX hat das Ziel, neue Technologien für die Erkundung schwer erreichbarer Gebiete mit extremen Umweltbedingungen zu entwickeln.

„Auftauchen wird der TRAMPER“, sagt Dr. Frank Wenzhöfer vom Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI) selbstbewusst. Der...

Im Focus: Mit Barcodes der Zellentwicklung auf der Spur

Darüber, wie sich Blutzellen entwickeln, existieren verschiedene Auffassungen – sie basieren jedoch fast ausschließlich auf Experimenten, die lediglich Momentaufnahmen widerspiegeln. Wissenschaftler des Deutschen Krebsforschungszentrums stellen nun im Fachjournal Nature eine neue Technik vor, mit der sich das Geschehen dynamisch erfassen lässt: Mithilfe eines „Zufallsgenerators“ versehen sie Blutstammzellen mit genetischen Barcodes und können so verfolgen, welche Zelltypen aus der Stammzelle hervorgehen. Diese Technik erlaubt künftig völlig neue Einblicke in die Entwicklung unterschiedlicher Gewebe sowie in die Krebsentstehung.

Wie entsteht die Vielzahl verschiedener Zelltypen im Blut? Diese Frage beschäftigt Wissenschaftler schon lange. Nach der klassischen Vorstellung fächern sich...

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Forscher entwickeln maisförmigen Arzneimittel-Transporter zum Inhalieren

Er sieht aus wie ein Maiskolben, ist winzig wie ein Bakterium und kann einen Wirkstoff direkt in die Lungenzellen liefern: Das zylinderförmige Vehikel für Arzneistoffe, das Pharmazeuten der Universität des Saarlandes entwickelt haben, kann inhaliert werden. Professor Marc Schneider und sein Team machen sich dabei die körpereigene Abwehr zunutze: Makrophagen, die Fresszellen des Immunsystems, fressen den gesundheitlich unbedenklichen „Nano-Mais“ und setzen dabei den in ihm enthaltenen Wirkstoff frei. Bei ihrer Forschung arbeiteten die Pharmazeuten mit Forschern der Medizinischen Fakultät der Saar-Uni, des Leibniz-Instituts für Neue Materialien und der Universität Marburg zusammen Ihre Forschungsergebnisse veröffentlichten die Wissenschaftler in der Fachzeitschrift Advanced Healthcare Materials. DOI: 10.1002/adhm.201700478

Ein Medikament wirkt nur, wenn es dort ankommt, wo es wirken soll. Wird ein Mittel inhaliert, muss der Wirkstoff in der Lunge zuerst die Hindernisse...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Wissenschaftliche Grundlagen für eine erfolgreiche Klimapolitik

21.08.2017 | Veranstaltungen

DGI-Forum in Wittenberg: Fake News und Stimmungsmache im Netz

21.08.2017 | Veranstaltungen

European Conference on Eye Movements: Internationale Tagung an der Bergischen Universität Wuppertal

18.08.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Forscher entwickeln zweidimensionalen Kristall mit hoher Leitfähigkeit

21.08.2017 | Physik Astronomie

Ein neuer Indikator für marine Ökosystem-Veränderungen - der Dia/Dino-Index

21.08.2017 | Ökologie Umwelt- Naturschutz

Kieler Wissenschaft entwickelt exzellentes Forschungsdatenmanagement

21.08.2017 | Informationstechnologie