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Brown University Researchers Change Sense of Novelty and Familiarity in Rats

Brown University scientists have used optogenetics to not only gain insight into recognition-related behaviour, but also take control of it in rats. The resulting paper, authored by Dr Rebecca D. Burwell et al, demonstrates exactly how the relevant brainwave patterns affect behaviour.


The Brown University team started from the knowledge that the crucial area of the brain when it comes to familiarity and novelty is the perirhinal cortex (PER). Using optogenetics, they manipulated neuron activity in the PERs of the rats, so the signals for familiar images resembled those for novel images and vice versa. This was achieved by placing the rats in a very basic maze divided to form two stalls. Images could be shown in each stall, and several days were allowed for the rats to become familiar with the environment. During the study, rats were first shown the same image in each stall. Then they were returned after a five-minute break to one of three scenarios: either there was a new image in one stall and a familiar one in the other, the same image was still showing in each stall, or both stalls had a new image.

Working on the basis that, like humans, rats will spend longer looking at a novel image than a familiar one, researchers timed how long rats spent looking at new and known images with and without stimulation. They experimented with different frequencies for the optogenetic stimulation, and found that that flickering the lights at 30 hertz when the rat was looking at a familiar image made the rat look at it for longer, as if it were new. Flickering the lights at 11 hertz appeared to convince the rats that new images were familiar. Outside of these frequencies, there were fewer clear behavioural effects.

On a cellular level, the stimulated cells in the PER network would fire faster, often in sync with the successful optogenetic frequencies. This has opened up the possibility for further research by the team, particularly around the way the PER and the prefrontal cortex interact.

This study was conducted using observation by researchers who, during testing sessions, did not know whether the rats were familiar with the images or not. They also did not know whether optogenetic stimulation was being used. Experiments like this demonstrate the vital importance of good, accurate testing data when it comes to all areas of science. Without highly specific timing information, for example, it would have been near impossible for Dr Burwell’s team to draw satisfactory conclusions. The need for greater accuracy and richer data in testing was a significant factor in our decision to design ActualHCA.

For more information on this study, read about it here in The Journal of Neuroscience. To read the article by Science Daily, click here. Alternatively, read the piece released by Brown University. For more details about ActualHCA, visit the product page or contact us today.