Credit: Thor Balkhed/Linköping University Special immune cells found in the brain, microglia, play a key role in the processes that make you feel uneasy and depressed in correlation with inflammation. This is the conclusion of a study using mice carried out by researchers at Linköping University, Sweden. The results have been published in the scientific journal Immunity, and suggest that microglial cells contribute to the negative mood experienced during several neurological diseases, and maybe also depression. David Engblom's research group at Linköping University has spent many years looking at why inflammation in the body, such as a common cold or influenza, causes us to feel poorly and despondent, and why we feel like retiring into our shell. The activity of the immune system influences nerve cells in some way. However, normal cells of the immune system are not able to get into the brain: it is sensitive and must be protected. Instead, the brain has its own special immune cells: microglial cells.