Depression and Schizophrenia: Shared neurological deficit

Max Planck Scientists discover the neurological basis of disturbed overnight memory consolidation

While we are asleep, our brain processes the new impressions we have gained during the day. For example, when a dancer learns a new choreography, the sequence of steps is “stored” in a specialized brain area, the hippocampus. This brain area is particularly involved in motor sequence learning. During sleep, the hippocampus distributes these new memories into existing networks via another specialized brain area, the prefrontal cortex. Thus, on the next day, the dancer has less difficulty in repeating the new choreography.

In patients suffering from depression or schizophrenia, however, the overnight memory consolidation of motor tasks is disturbed. At the Max Planck Institute of Psychiatry in Munich, sleep- and neuroscientists taught healthy controls and depressed or schizophrenic patients a simple finger tapping sequence. Both during the learning process and during the repetition of the finger tapping sequence on the next day, the scientists measured the brain activity using magnet resonance imaging.

“Compared to healthy subjects, we confirmed that the deficit in the patients is caused by a decreased connectivity between the hippocampus and the prefrontal cortex,” states Lisa Genzel, first author of the current study. “Interestingly, this decreased connectivity is a common neurologic element in the pathophysiology of both depression and schizophrenia. At least in some aspects, the two diseases are not so different at all.”

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