Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers Discover Brain Circuits Enabling Hearing Develop Without Sensory Experience

22.06.2010
Using a newly applied scientific technique, researchers at the Keck School of Medicine of the University of Southern California (USC) have reached surprising findings about the role of nature versus nurture in the development of the neural circuits in the auditory cortex, the area of the brain that is responsible for processing information about sound. The discoveries will be published in the June 17 issue of Nature journal.

Two research teams at the Zilkha Neurogenetic Institute (ZNI) found that before an animal model had any hearing experience, the brain’s elementary thalamocortical circuits with balanced excitation and inhibition functions – a feature of brain activity essential for normal functions -- had already formed.

“The scientific view had been that sensory experience should play an instructive role in the initial formation of appropriate brain circuits, so this is a big surprise,” said Li Zhang, assistant professor of Physiology and Biophysics at the Keck School of Medicine, researcher at ZNI and principal investigator on the study. “Because the circuits had already formed, no sensory experience was required.”

With an eye toward future medical advances, the study is a step in addressing a major debate in neuroscience over the last century: What are the roles of genetics and environment in the development of the human nervous system?

“In general we know that both factors play essential roles in the establishment of neural circuits,” said Zhang. “The question is which factor plays a dominant role in the different stages of development, and how. It’s a difficult question to resolve because of the dauntingly complex structure of the brain.”

Their second finding is about how the circuits change during development. They found that after the onset of hearing an elegant refinement of the neuron’s excitation function takes place.

“Previously, it was thought that a pruning of profuse connectivity was responsible for the sharpening of sensory receptive fields of neurons, which leads to improved sensory processing during development,” said Zhang. “We now see that the sharpening depends more on fine adjustments in the strength of excitatory neural connections, and that modulations of the excitatory and inhibitory connections lead to a slight breakdown of the priorly formed excitation–inhibition balance.”

Key to these findings, Zhang said, was a new method of studying the functional neural circuitry of the brain. In the experimental setting, the researchers surgically exposed the cortex of the brain of a young anesthetized rat. They used glass microelectrodes to reach and patch onto neurons buried in the cortical tissue, and then break into their membranes in order to monitor their electrical activity. That allowed the researchers to separately record the inhibition and excitation functions of the neurons.

“This is the first time anyone has applied this cutting-edge electrophysiological technique – in vivo whole-cell voltage-clamp recording – to the developing cortex of the brain,” Zhang said. “Previous hypotheses were limited by techniques that couldn’t reveal detailed structure and subtle changes.”

One research team was led by Zhang, and the other was led by Huizhong W. Tao, an assistant professor in the Department of Cell and Neurobiology at the Keck School.

Currently, Zhang’s research team is examining how the neural circuitry is affected when animals are exposed to noise. “One potential extension of this research line is in looking at how environmental factors play a role in further sculpting the circuits during later development,” he said. In the future, he noted, such research may open the door to insights about the cause of disorders such as autism, in which it is speculated that the auditory system is a major target.

Leslie Ridgeway | Newswise Science News
Further information:
http://www.usc.edu

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>