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 »

Activity 
6/7/12 
Brain Cell Activity Imbalance May Account for Seizure Susceptibility in Angelman Syndrome
By University of North Carolina Health Care
CHAPEL HILL, N.C. – New research by scientists at the University of North Carolina School of Medicine may have pinpointed an underlying cause of the seizures that affect 90 …
Inhibitory 
8/26/13 
Researchers Discover How Inhibitory Neurons Behave During Critical Periods of Learning
By Carnegie Mellon University
PITTSBURGH—We've all heard the saying "you can't teach an old dog new tricks." Now neuroscientists are beginning to explain the science behind the adage. …
Inhibition 
8/8/12 
Simple Mathematical Computations Underlie Brain Circuits
By Massachusetts Institute of Technology
CAMBRIDGE, MA -- The brain has billions of neurons, arranged in complex circuits that allow us to perceive the world, control our movements and make decisions. Deciphering those circuits …
Brain 
10/16/13 

When Neurons Have Less to Say, They Speak Up
By Max-Planck-Gesellschaft
Types 
5/26/13 
'Should I Stay Or Should I Go?' CSHL Scientists Link Brain Cell Types to Behavior
By Cold Spring Harbor Laboratory
Cold Spring Harbor, N.Y. – You are sitting on your couch flipping through TV channels trying to decide whether to stay put or get up for a snack. Such …
Inhibitory 
4/11/12 
Distinct Brain Cells Recognize Novel Sights
By Brown University
No matter what novel objects we come to behold, our brains effortlessly take us from an initial "What's that?" to "Oh, that old thing" after a few casual encounters. …
Brain 
5/27/14 
Dealing with Stress - to Cope Or to Quit?
By Cold Spring Harbor Laboratory
Cold Spring Harbor, NY – We all deal with stress differently. For many of us, stress is a great motivator, spurring a renewed sense of vigor to solve life's …
More » 
 
© Newsline Group  |  About  |  Privacy Policy  |  Feedback  |  Mobile  |  Japanese Edition