A stress hormone may interfere with the brain’s built-in navigation system, according to a new study reported by ScienceDaily.
Researchers at Ruhr University Bochum in Germany found that cortisol weakened the activity of grid cells, a type of nerve cell in the entorhinal cortex that helps people keep track of where they are. In the imaging study, 40 healthy men completed a virtual navigation task while their brain activity was measured with MRI.
Participants took part in two sessions on separate days. In one session they received 20 milligrams of cortisol, and in the other they received a placebo. When they had cortisol in their system, they struggled more with the spatial task and made larger errors while trying to navigate back to their starting point.
The effect showed up whether or not a fixed landmark was available, though it was strongest when no permanent landmarks were present. Researchers also saw less distinct grid-like activity in the brain after cortisol, while activity in the caudate nucleus increased, suggesting the brain may shift to other navigation strategies when its main system is disrupted.
The findings, published in PLOS Biology, may also be relevant to Alzheimer’s disease because the entorhinal cortex is one of the first brain regions affected by the condition, according to the researchers.
