Researchers report that a set of brain cells linked to spatial disorientation in Alzheimer’s disease has been preserved across millions of years of evolution. These cells are located in the retrosplenial cortex, a brain area that helps animals and people know where they are and how to travel between familiar places. Charles Darwin described the underlying ability as "dead reckoning." Omar Ahmed, the senior author, said the retrosplenial cortex acts as a subconscious GPS with specialized neurons that calculate direction toward a desired destination. He also noted the region is active when people imagine themselves in a future time or place and that it is among the first regions affected in Alzheimer’s disease.
Ahmed’s group first identified a unique neuron type in the mouse retrosplenial cortex. In the new study, first author Isla Brooks and colleagues applied advanced AI-based tools to compare genetic signatures of neurons from mice and rats. Despite the large evolutionary distance, the team found the unique neuron type was remarkably well preserved in rats. They also discovered a second specialized neuron type restricted to the retrosplenial cortex; this type was preserved across species and slightly amplified in the rat.
By comparing thousands of genes across thousands of neurons from distinct species, the researchers say they can ask how specific neuron types change across evolution. The authors argue these neurons are likely important for survival because they help animals find their way home. Ahmed’s lab is now investigating whether the same specialized neurons exist in the human retrosplenial cortex and what happens to them in Alzheimer’s disease, with the aim of working toward targeted therapies to repair the neurons. The research appears in the Journal of Neuroscience and was supported by the National Institutes of Health and the Alzheimer’s Association.
Difficult words
- retrosplenial cortex — brain area that helps know location and direction
- spatial disorientation — difficulty knowing where you are in space
- neuron — a brain cell that sends electrical signalsneurons
- preserve — keep something in the same state over timepreserved
- dead reckoning — estimating position by tracking distance and direction
- genetic signature — a pattern of genes that identifies cell typesgenetic signatures
- targeted therapy — medical treatment aimed at a specific problemtargeted therapies
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Discussion questions
- What practical benefits could come from finding the same specialized neurons in humans?
- How could the preservation of these neurons across species influence Alzheimer’s research?
- What ethical or scientific challenges might researchers face when developing targeted therapies to repair neurons?
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