Neural GPS: Alzheimer's and the Brain

Posted by: Mike Pallante on August 10, 2011 at 5:26PM
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The April 29 issue of the scholarly journal Science contains a report from biologists at UC San Diego about how human brains map their environment.

Your Internal GPS

Tests conducted on rats in 2005 by Norwegian scientists demonstrated that three types of cells in the rodent's neural networks created a sort of "internal GPS" system. A neuron scientists call "place cells" activated when the rats were in a specific place in the room; other "place cells" activated when the rats were in different places. A second group of neurons scientists call "head cells" are responsible for a rat's knowledge of left, right up and down relative to their position. The final group of neurons - "grid cells"- are located in a grid pattern within the brain and provide a memory of dimensions of an environment.


The research in April 29's Science demonstrates how similar cells located in the entorhinal cortex of human brains, most notably the grid cells, work. In the 2005 test, the rat subjects created a grid-like neural map of their environment. Equilateral triangles of "grid cells" became active when the rodents moved into the corresponding area of the physical environment like a GPS showing your latitude and longitude.

Defining Goals: A Better Understanding of Alzheimer’s

Lead researcher Stefan Leutgeb commented, "Our findings represent a major milestone in understanding memory processing, and they will guide efforts to restore memory function when cells in the entorhinal cortex are damaged."

The major impact of this research comes in its applications for Alzheimer’s- the research was funded in part by the Alzheimer's Association.

When scientists inhibited “grid cell” activity in test subjects they found that “head cells” and “place cells” still provided accurate information on the subject's location in an environment.

"...there was the assumption that grid cells would have a very large impact on place cells. We are surprised at how the function of place cells is maintained in the face of significant disruption in grid cell function," said Leutgeb.

Leutgeb continued, "This important result shows that, in general, you can eliminate a substantial amount of incoming information to a brain circuit without that brain circuit losing a majority of its functionality. The implication of this finding is that restoring memory function does not require that we exactly reassemble damaged neural circuitry, rather we can regain function by preserving or restoring key components."

"Our findings are a major step towards identifying these key components in an effort to preserve memory function in aging individuals and in patients with neurodegenerative diseases.”