A brain structure called the habenula is crucial for modifications of fear responses in zebrafish, according to a new study by researchers from the RIKEN Brain Science Institute, Wako(1). The zebrafish dorsal habenula is subdivided into two regions, each connected to different brain structures, but the function of each, and the significance of their connections, was unclear.
Hitoshi Okamoto and his colleagues used fluorescent dyes to trace the neural pathways from the interpeduncular nucleus (IPN), which recves connections from the dorsal habenula region . They fond that the dorsal IPN projects to midbrain structures called the dorsal raphe nucleus and griseum centrale. The corresponding structures in the mammalian brain have been implicated in responses to fear and stress, suggesting that the habenula–IPN pathway in zebrafish is also involved in these responses.
To investigate this, the researchers created transgenic zebrafish expressing tetanus toxin in the lateral subnucleus of the dorsal habenula. The toxin blocks neurotransmission, preventing neurons in that region from sending signals.
The transgenic fish were then subjected to an established fear conditioning task, in which a red light is repeatedly paired with an electric shock. Normally, the fish learn to associate the two stimuli, and become agitated—recognized by an increase in the frequency of turning—in the presence of the light alone. However, when the transgenic fish encountered the red light after the fear conditioning task, they froze rather than escaping. Okamoto and colleagues observed these differences between the transgenic fish and controls during the fear conditioning task. Both froze the first time they encountered the red light; the controls started to become agitated the second time, but the transgenic fish continued to freeze.
The exploratory behavior of the transgenic fish was no different from that of the controls, showing that their responses to fear conditioning were not due to abnormal sensory or motor function. Instead, the results suggest to the researchers that the transgenic fish cannot modify their fear response after new experiences. They therefore conclude that experience-dependent modifications of fear responses are controlled by the neurons in the lateral subnucleus of the dorsal habenula in the zebrafish.
“We would like to know whether the same regulation mechanism works in mammals, including humans,” says Okamoto, “and would also like to extend our research to reveal the functions of the other parts of the habenula.”
The corresponding author for this highlight is based at the Laboratory for Developmental Gene Regulation, RIKEN Brain Science Institute.
1. Agetsuma, M., Aizawa, H., Aoki, T., Nakayama, R., Takahoko, M., Goto, M., Sassa, T., Amo, R., Shiraki, T., Kawakami, K., et al. The habenula is crucial for experience-dependent modification of fear responses in zebrafish. Nature Neuroscience 13, 1354–1356 (2010).
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
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,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences