Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Revealing the stars of brain adaptability

15.05.2012
Star-shaped brain cells called astrocytes are found to bridge the gap between global brain activity and localized circuits. Global network activity in the brain modulates local neural circuitry via calcium signaling in non-neuronal cells called astrocytes (Fig. 1), according to research led by Hajime Hirase of the RIKEN Brain Science Institute.
The finding clarifies the link between two important processes in the brain.

Activity in large-scale brain networks is thought to modulate changes in neuronal connectivity, so-called ‘synaptic plasticity’, in the cerebral cortex. The neurotransmitter acetylcholine regulates global brain activity associated with attention and awareness, and is involved in plasticity.
To investigate how these processes are linked, Hirase and his colleagues simultaneously stimulated the whiskers of mice and the nucleus basalis of Meynert (NBM), a basal forebrain structure containing neurons that synthesize acetylcholine and project widely to the cortex. Using electrodes and an imaging technique called two-photon microscopy, performed through a ‘cranial window', they monitored the responses of cells in the barrel cortex, which receives inputs from the whiskers.

Recordings from the electrodes showed that repeated co-stimulation of the whiskers and NBM induced plasticity in the barrel cortex. This plasticity depended on two types of receptors—muscarinic acetylcholine receptors (mAChRs) and N-methyl-D-aspartic acid receptors (NMDARs). Two-photon imaging microscopy further revealed that activation of the mAChRs during co-stimulation elevated the concentration of calcium ions within astrocytes of the barrel cortex.

The researchers repeated these experiments in mutant mice lacking the receptor that controls the release of calcium ions in astrocytes. Since co-stimulation of whiskers and NBM did not induce plasticity in the mutants, Hirase and colleagues concluded that calcium signaling in astrocytes acts as a ‘gate’ linking the changes in global brain state induced by acetylcholine to activity in local cortical circuits.

Figure 1: Astrocytes are star-shaped cells with numerous fine projections that ensheath synapses in the brain. Copyright : © 2012 Hajime Hirase

Furthermore, the researchers found that stimulation of the NBM led to an increase in the extracellular concentration of the amino acid D-serine in the normal, but not the mutant, mice. D-serine is secreted by astrocytes and activates NMDARs. Hirase’s team had previously shown that astrocytes are electrically silent in living rodents even in the presence of neural activity. The new findings showed that the biochemical, as opposed to electrical, activation of astrocytes induces them to release the transmitter that modulates synaptic plasticity in the neuronal circuitry.

“Our study is probably the first to show that calcium signaling in astrocytes is related to neuronal circuit plasticity in living animals,” says Hirase. “We are now studying if this type of calcium signaling occurs in all parts of an astrocyte or is restricted to some parts of the cell.”

The corresponding author for this highlight is based at the Laboratory for Neuron–Glia Circuitry, RIKEN Brain Science Institute

References:

1.Takata, N., Mishima, T., Hisatsune, C., Nagai, T., Ebisui, E., Mikoshiba, K. & Hirase, H. Astrocyte calcium signaling transforms cholinergic modulation to cortical plasticity in vivo. The Journal of Neuroscience 31, 18155–18165 (2011).

2.Mishima, T. & Hirase, H. In vivo intracellular recording suggests that gray matter astrocytes in mature cerebral cortex and hippocampus are electrophysiologically homogeneous. The Journal of Neuroscience 30, 3093–3100 (2010).

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

Further reports about: Brain Hirase NBM NMDARs Neuroscience RIKEN Science TV calcium ions calcium signaling cerebral cortex

More articles from Life Sciences:

nachricht Closing in on advanced prostate cancer
13.12.2017 | Institute for Research in Biomedicine (IRB Barcelona)

nachricht Visualizing single molecules in whole cells with a new spin
13.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>