Chuck Bednar for redOrbit.com – @BednarChuck
A team of French neuroscientists has effectively hacked the brains of sleeping mice, implanting false memories using electrodes to directly stimulate and record nerve cell activities, according to new research published online Monday in the journal Nature Neuroscience.
Their technique created artificial associative memories that remained throughout the creatures’ sleep, and altered their behavior after they woke up, according to The Guardian. While this is far from the only time that scientists have altered brain cells in the laboratory, it demonstrates for the first time that fake memories can be implanted into the brains of sleeping animals.
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Furthermore, the study provides new insight into how nerve cells encode spatial memories, as well as the role of sleep in making those memories stronger. It shows how the brain replays the day’s events during slumber, New Scientist explained, and the methods used in the study could one day be used to alter the memories of people who have experienced traumatic events.
I distinctly remember there being cheese here?
As part of their work, Karim Benchenane of the French National Centre for Scientific Research (CNRS) and his colleagues implanted electrodes into the brains of 40 mice. Specifically, they focused on the medial forebrain bundle (MFB), which is involved in the reward process, and the CA1 region of the hippocampus, which helps encode spatial navigation-related memories.
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The rodents were then left alone to explore their surroundings as the scientists monitored how their hippocampal neurons fired when each of them entered was in a specific location or “place field” within their environment. In one part of the experiment, they timed electrical stimulation of the MFB in five awake mice to coincide with the firing of a specific location’s cell.
Later, as the mice were sleeping, the researchers monitored the animals’ brain activity as they replayed the day’s experiences. A computer recognized when the specific place cell fired, and as it did, a second electrode would cause the reward area of the brain to become stimulated, creating a false associative memory in the creatures’ brains.
The mice came to associate that location with a reward, and when they woke up, immediately traveled to that area, spending between four to five more time there than two control mice that were administered MFB stimulation that did not coincide with location-related neural activity. The findings indicate that a new memory linking the location with a reward had formed.
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“The mouse is remembering enough abstract information to think ‘I want to go to a certain place’, and go there when it wakes up,” University College London neuroscientist Neil Burgess told New Scientist. “It’s a bigger breakthrough [than previous studies] because it really does show what the man in the street would call a memory – the ability to bring to mind abstract knowledge which can guide behavior in a directed way.”
“This is exciting because it provides excellent evidence for the importance of place cells in guiding navigation to goals,” Hugo Spiers, a spatial cognition researcher at UCL, added in an interview with The Guardian. “It is also remarkable that the authors have been able to incept a false memory into the brain during sleep using this method.”
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