(June 26, 2015) When
rats rest, their brains simulate journeys to a desired future such as a tasty
treat, finds new UCL research funded by the Wellcome Trust and Royal Society.
The researchers monitored brain activity in rats, first as
the animals viewed food in a location they could not reach, then as they rested
in a separate chamber, and finally as they were allowed to walk to the food.
The activity of specialised brain cells involved in navigation suggested that
during the rest the rats simulated walking to and from food that they had been
unable to reach.
The study, published in the open access journal eLife, could
help to explain why some people with damage to a part of the brain called the
hippocampus are unable to imagine the future.
“During exploration, mammals rapidly form a map of the
environment in their hippocampus,” says senior author Dr Hugo Spiers (UCL
Experimental Psychology). “During sleep or rest, the hippocampus replays
journeys through this map which may help strengthen the memory. It has been
speculated that such replay might form the content of dreams. Whether or not
rats experience this brain activity as dreams is still unclear, as we would
need to ask them to be sure! Our new results show that during rest the
hippocampus also constructs fragments of a future yet to happen. Because the
rat and human hippocampus are similar, this may explain why patients with
damage to their hippocampus struggle to imagine future events.”