Home  |  Top News  |  Most Popular  |  Video  |  Multimedia  |  News Feeds  |  Feedback
  Medicine  |  Nature & Earth  |  Biology  |  Technology & Engineering  |  Space & Planetary  |  Psychology  |  Physics & Chemistry  |  Economics  |  Archaeology
Top > Biology > GPS in the Head? … >
GPS in the Head?

Published: September 15, 2011.
By Ruhr-University Bochum
http://www.ruhr-uni-bochum.de

Prof. Dr. Motoharu Yoshida and colleagues from Boston University investigated how the rhythmic activity of nerve cells supports spatial navigation. The research scientists showed that cells in the entorhinal cortex, which is important for spatial navigation, oscillate with individual frequencies. These frequencies depend on the position of the cells within the entorhinal cortex. "Up to now people believed that the frequency is modulated by the interaction with neurons in other brain regions", says Yoshida. "However, our data indicate that this may not be the case. The frequency could be fixed for each cell. We may need new models to describe the contribution of rhythmic activity to spatial navigation." The researchers report in the Journal of Neuroscience.

Rhythmic brains find their way

„The brain seems to represent the environment like a map with perfect distances and angles", explains Yoshida. "However, we are not robots with GPS systems in our head. But the rhythmic activity of the neurons in the entorhinal cortex seems to create a kind of map." The activity of individual neurons in this brain region represents different positions in space. If an animal is in a certain location, a certain neuron fires. The rhythmic activity of each cell may enable us to code a set of positions, which form a regular grid. Computer simulations of previous studies suggested that signals from cells in other brain regions influence the rhythmic activity of the entorhinal neurons. Using electrophysiological recordings in rats and computer simulations, Yoshida and his colleagues examined the nature of this influence.

Expressing the cellular rhythm in numbers

In order to simulate the input signals from other cells, Yoshida and his colleagues varied the voltage at the cell membrane (membrane potential). A change of the membrane potential from the resting state to more positive values thereby resembled an input signal from another cell. The membrane potential of the cells in the entorhinal cortex is not constant, but increases and decreases periodically; it oscillates. The scientists determined how fast the membrane potential changed (frequency) and how large the differences in these changes were (amplitude), when they shifted the mean membrane potential around which the potential oscillated.

Position determines the frequency

In the resting state, the membrane potential oscillations of the entorhinal cells were weak and in a broad frequency range. If the membrane potential was shifted to more positive values, thus mimicking the input of another cell, the oscillations became stronger. Additionally, the membrane potential now fluctuated with a distinct frequency, which was dependent on the position of the cell within the entorhinal cortex. Cells in the upper portion of this brain region showed oscillations with higher frequency than cells in the lower portion. However, the frequency was independent of further changes in membrane potential and thus largely independent of input signals from other cells.


Show Reference »


Translate this page: Chinese French German Italian Japanese Korean Portuguese Russian Spanish


 
All comments are reviewed before being posted. We cannot accept messages that refer a product, or web site.If you are looking for a response to a question please use our another feedback page.
Related »

Brain 
7/24/13 
Neural Simulations Hint at the Origin of Brain Waves
By Ecole Polytechnique Fédérale de Lausanne
For almost a century, scientists have been studying brain waves to learn about mental health and the way we think. Yet the way billions of interconnected neurons work together …
Brain 
3/19/14 
Study Describes First Maps of Neural Activity in Behaving Zebrafish
By JLM&A, SA
In a study published today (19/3/2014) in the scientific journal Neuron, neuroscientists at the Champalimaud Foundation, in collaboration with neuroscientists from Harvard University, describe the first activity maps at …
Brain 
10/16/13 

When Neurons Have Less to Say, They Speak Up
By Max-Planck-Gesellschaft
Brain 
4/11/11 
★★★★ 
Mapping the Brain: New Technique Poised to Untangle the Complexity of the Brain
By Wellcome Trust
Scientists have moved a step closer to being able to develop a computer model of the brain after developing a technique to map both the connections and functions of …
Memory 
3/15/12 
Princeton Scientists Identify Neural Activity Sequences That Help Form Memory, Decision-making
By Princeton University
Princeton University researchers have used a novel virtual reality and brain imaging system to detect a form of neural activity underlying how the brain forms short-term memories that are …
Visual 
10/28/13 
Smart Neurons: Single Neuronal Dendrites Can Perform Computations
By University College London
When you look at the hands of a clock or the streets on a map, your brain is effortlessly performing computations that tell you about the orientation of these …
Brain 
6/29/10 
NYU Researchers Identify a Key Mechanism in the Brain's Computation of Sound Location
By New York University
New York University researchers have identified a mechanism the brain uses to help process sound localization. Their findings, which appear in the latest edition of the journal PLoS Biology, …
More » 
 
© Newsline Group  |  About  |  Privacy Policy  |  Feedback  |  Mobile  |  Japanese Edition
All contents are copyright of their owners except U.S. Government works. U.S. Government works are assumed to be in the public domain unless otherwise noted. Everything else copyright ScienceNewsline.