During sleep, the hippocampus distributes new memories into existing networks via the prefrontal cortex (which coordinates thoughts and actions).
Lisa Genzel, PhD, from the University of Edinburgh, Scotland, has investigated the role of sleep spindles in people with depression or schizophrenia. She has found that the consolidation of their memories of motor tasks is disturbed. While healthy people show an overnight increase in performance which is dependent on sleep, patients with schizophrenia and depression fail to show the same improvement.
Working with sleep scientists and neuroscientists at the Max Planck Institute of Psychiatry in Munich, they taught healthy people and depressed or schizophrenic patients (16 people in each group) a simple finger tapping sequence. They scanned the people’s brains both during the learning process and again the following day to measure the brain activity.
“When we compared the ability to learn the finger-tapping sequence, we found that that the deficit in the people with schizophrenia and depression is caused by a decreased connectivity between the hippocampus and the prefrontal cortex,” said Genzel at FENS [Federation of European Neuroscience Societies]. She believes that this contributes to the progression of the disease.