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A Princeton University and National Institutes of Health study suggests that our response to stressful situations originates from structural changes in our brain that allows us to adapt to turmoil. Adult rats with disruptions in their social hierarchy produced far fewer new neurons in the hippocampus, the part of the brain responsible for certain types of memory and stress regulation. They also reacted to the disruption by favoring the company of familiar rats. Their behavior manifested six weeks after social disruption, during which time brain-cell growth, or neurogenesis, had decreased by 50 percent. The photo shows adult hippocampal neurons that are less than two weeks old.
A Princeton University and National Institutes of Health study suggests that our response to stressful situations originates from structural changes in our brain that allows us to adapt to turmoil. Adult rats with disruptions in their social hierarchy produced far fewer new neurons in the hippocampus, the part of the brain responsible for certain types of memory and stress regulation. They also reacted to the disruption by favoring the company of familiar rats. Their behavior manifested six weeks after social disruption, during which time brain-cell growth, or neurogenesis, had decreased by 50 percent. The photo shows adult hippocampal neurons that are less than two weeks old.
The study involves rats running on treadmill, and focuses on specific neurons called grid cells which support navigation in time and space, even without visual landmarks and the optic flow.
Until now, there was no direct evidence demonstrating that the grid cells help the brain determine the distance and time passed.
To prove the contrary, researchers put rats on treadmills and recorded the activity of grid cells, keeping either distance or duration of running unchanged, and only varying the speed.
As a result, 92% of grid cells in rats emitted signals at specific moments: for instance, one cell would fire 8 seconds into the run, not taking into account speed or distance covered, and another cell would emit a signal every 400 cm, not depending on speed or duration of the run.
50 percent of the cells were affected by distance, another half by time, and around 40 percent by both factors.
Comment: See also: The Corruption of Science in America