Social Isolation study using the Marlau Cages, for environmental enrichment

Published: 04-08-2020 In Actualité

Tags: Marlau Cage

An experiment with mice shows how crucial physical contact with peers is. Isolated, their working memory and their attention span deteriorate and they make fewer new brain cells. Neurobiologist Ann Van der Jeugd (KU Leuven) divided forty adult mice into two groups. Half of them were placed in a cage by themselves and could still see and hear their peers, but they felt less and did not touch them at all. The other half stayed together and served as a control group. After a month, Van der Jeugd passed all kinds of tests on the animals. This showed that socially isolated mice had memory problems. They also became more anxious, their sleep-wake rhythm was disturbed, and later showed less interest in social interaction. All this was tested, among other things, by running the mice in a labyrinth. “The socially isolated mice continued to walk much more in the closed arms of the labyrinth, showing that they were more anxious. They explored less and did not remember where they had already been, ”explains Van der Jeugd. Alzheimer's Van der Jeugd prefers not to draw conclusions that are too drastic for people. But that's why she does this kind of research. “Mice, like humans, are social creatures. They eat, drink and play together and make nests together. You could compare a month of isolation in a mouse life to three years in a human life. So those few weeks of corona quarantine we're dealing with now may not have as much of an impact on our brains. “I set up this experiment to discover what could be the impact of the loss of your partner at an advanced age, in particular in people suffering from Alzheimer's disease. Therefore, I repeated this experiment later with mice that were modified to show symptoms of Alzheimer's disease at the age of six months. The impact of social isolation was even greater in this group. They had the same kind of memory problems. They also became aggressive and were more difficult to recognize objects. They also began to explore labyrinths in a much less systematic way and were less able to remember where they had already been. " Social isolation creates stress The symptoms that mice without Alzheimer's also showed are similar to those with Alzheimer's. “My hypothesis is that protein deposits, so typical of Alzheimer's disease, do not necessarily have to lead to the disease. There are people who show a lot of these accumulations of beta-amyloid protein and still don't get sick. A trigger may be necessary for the disease to manifest. One of these potential triggers could be social isolation. " Because social isolation creates stress, explains Van der Jeugd. She could also demonstrate this in her test mice. Isolated animals had increased levels of stress hormone cortisol in their blood. Van der Jeugd also later examined the brains of healthy mice. In the isolated group, she saw that fewer new neurons and fewer new connections between neurons were created in the hippocampus, the region of the brain that is important for memory. "So less information can be stored," says Van der Jeugd. She doesn't yet know how the Alzheimer's brain is doing. “The study is currently on hold because we cannot go to the laboratory because of the corona attack. The brain is waiting for us in the freezer. " Socially isolated mice continue to walk much more in the closed arms of the labyrinth. A different labyrinth every day Much research has already been done on the impact of social isolation at a young age. For children - and young mice - it is crucial, for example, to learn to speak or work together. Physical and social contact also seems important in adulthood and old age. "The message is clear," says Van der Jeugd. "Stay social!" The neurobiologist is currently studying whether the consequences of social isolation can still be reversed. “We are looking at the effect of physical activity, social stimulation and cognitive stimulation. The mice are placed in a cage with a spinning wheel, in a cage with other animals and in a cage with a labyrinth that changes daily. " “We are busy analyzing the results, but we are already finding that cognitive stimulation brings the most relief. Unfortunately we don't see any improvement in the sour group