New research conducted on rats suggests that while they’re asleep they dream of how to accomplish a certain task, particularly if they have a strong motivation, such as…food.
Researchers at the University College London have tracked neural activity in the rats’ brains while they were placed in a T-shaped maze. Secondly, neural activity in the rodents’ hippocampi was analyzed as the furry subjects were taking a comfy nap in their nest.
Researchers set out to understand how the mind maps places even before they have been explored.
Therefore, four rats were placed in the T-shaped maze. The two arms of the maze were blocked by clear barriers, leaving the curious rats to wonder on a straight path. In one of the arms the researchers placed one trigger for the rats: food.
As the rodents were exploring the maze and realized they can’t reach the food, their neural activity was mapped with the use of electrodes. What the researchers observed was that location mapping followed the same process as it would with humans.
‘Place cells’ are neural connections responsible for storing memories connected to location and mental mapping, found in the hippocampi. When the rats were in one spot of the maze, one specific set of ‘place cells’ was observed firing up.
Another spot would trigger the same process in a different ‘place cell’ set. Put together, these form the memories that comprehensively add up to form a map.
After the rats were left to analyze every corner of the path that wasn’t blocked, they were returned to their nest where a healthy session of sleep took over. During their nap, researchers also analyzed the rats’ neural activity.
It turned out that the mental mapping process that the team had observed while the rats were wandering in the T-shaped maze was identical to the ‘place cells’ that were firing up during the rodents’ sleep. Albeit only 8 percent, it was enough for the rats to figure out the exact path to reach their treat at the end of the journey.
There was no indication that the arm of the T-shaped maze that held no yummy treat for the rodents was even remotely taken into consideration. The ‘place cells’ pinpointing this location remained fully unactivated.
As they were returned to the T-shaped maze that was meanwhile fully accessible, the rats ‘place cells’ were seen to be firing in the same manner they had during sleep. Thus, they were able to reach the teasing food previously place behind a transparent barrier.
Hugo Spiers, one author of the paper detailing the experiment stated that this indicates a great amount of neural activity to be devoted to one task during sleep.
Another author of the paper, Dr. Freyja Olafsdottir commented:
“What’s surprising here is that we see the hippocampus planning for the future, actually rehearsing totally new journeys that the animals need to take in order to reach the food”.
The furry subjects of the experiment not only dream of the places where food is, but also of how to get their paws on it.
For humans, sleep significantly improves memory task performance. Thus, in the case of this experiment, it still remains unclear whether the goal-oriented mental mapping is linked to dreaming or another process.
Further research will certainly ensue. For now, the results of the University College London study are published in the eLife journal.
Image Source: camerafraud.com
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