Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Finding out how neurons fire

28.11.2011
Research on the mechanism that controls neuron firing in the rat brain reveals a surprise for neuroscientists

Contrary to expectations that the neurotransmitter GABA only inhibited neuronal firing in the adult brain, RIKEN-led research has shown that it can also excite interneurons in the hippocampus of the rat brain by changing the conductance of ions across the membranes of these cells1.

According to conventional wisdom, activation of the GABAA receptor subtype at the communication junction between neurons—the synapse—strongly increases membrane conductance of ions, triggering a process called shunting, which inhibits neuronal firing. Led by Alexey Semyanov of the RIKEN Brain Science Institute in Wako, the team demonstrated that activation of these receptors outside of synaptic junctions, so-called ‘extrasynaptic receptors’ can also excite the neurons.

Further activation of these extrasynaptic receptors by application of higher concentrations of GABA turn excitation into inhibition. “To our knowledge, this is the first demonstration that changes in membrane conductance can switch the action of a neurotransmitter from excitation to inhibition,” Semyanov says.

Semyanov and colleagues treated slices of the mouse hippocampus with low or high concentrations of GABA and compared the effects. They showed that the more GABA they added, the more they could detect an increase in the conductance of the membranes of hippocampus cells called CA1 interneurons. The increased conductance was mediated through extrasynaptic GABAA receptors.

The CA1 interneurons could spontaneously fire action potentials—electrical impulses that transfer signals in the network of interconnected neurons. Adding low concentrations of GABA increased the rate of action potential firing, while high concentrations of GABA reduced action potential firing in the cells. Because the concentration of GABA that slowed neuronal firing had also enhanced membrane conductance, the researchers argue that increasing this conductance by activating extrasynaptic GABAA receptors can result in inhibition via shunting along the membrane, which would cause a decrease in action potential generation in the neurons.

The hippocampus plays a key role in learning and memory, and GABA concentrations are known to increase in this part of the brain during exploratory behavior in rats. The findings therefore raise the intriguing possibility that changes in GABA concentration in the brain during some behavioral tasks could bidirectionally change neuronal excitability; this could be a characteristic of the hippocampal neuronal network that may be required for some behavioral tasks in animals.

“Many clinically used drugs, such as sedatives or anti-epileptics, target GABA receptors,” notes Semyanov. “Our findings could potentially explain their therapeutic action as well as some of their unwanted side effects.”

The corresponding author for this highlight is based at the Semyanov Research Unit, RIKEN Brain Science Institute

gro-pr | Research asia research news
Further information:
http://www.riken.jp
http://www.researchsea.com

More articles from Health and Medicine:

nachricht Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care

nachricht Disrupted fat breakdown in the brain makes mice dumb
19.05.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

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

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>