Abnormalities in the way memories are replayed in the brains of people with schizophrenia have been identified for the first time, it was revealed yesterday.
Neuroscientists at UCL, UK, say their pathbreaking study, carried out at the UCL Max Planck Centre for Computational Psychiatry and Ageing and which is published in the newest edition of Cell, provides a new basis for explaining many of the condition’s core symptoms.
Theirs is the first research to demonstrate a link between abnormal neural replay and schizophrenia and they hope their findings might lead to detection of the disorder at a much earlier stage and provide a basis for examining novel treatment options.
The neuroscientists enrolled 55 participants, 28 with schizophrenia – 13 of whom were unmedicated – and 27 healthy volunteers and used magnetoencephalography (MEG) and machine learning tools to measure and assess neural activity that correspond to inner states of mind during rest periods when the brain is consolidating its prior experiences.
Each participant was given an abstract rule, for example [A ? B ? C ? D], and they had to arrange in their minds a series of presented pairs of images into two distinct groups and sequences, by applying an abstract rule they had learned.
Once participants had completed the tasks they relaxed for five minutes, which allowed the brain to enter a rest period. It is at this point the brain subconsciously replays its prior experiences using neural replay, which is believed to be an important mechanism for memory consolidation, inference and belief formation.
During both the task phase and rest phase, participants were seated, awake and their brains were monitored by the MEG.
When the researchers analysed the MEG neural activity data, they found participants with schizophrenia were far less able to “build a structure” of the task. This behavioural impairment was directly linked to an impoverished expression of neural replay measured during a post-task rest-period.
However, healthy volunteers were able to complete the task in a correct pattern of replay.
Lead author Dr Matthew Nour, of the UCL Queen Square Institute of Neurology, said: “These findings raise the tantalising possibility that subtle impairments in memory replay might result in alterations in memory consolidation and belief formation and thus explain previously mysterious aspects of schizophrenia.
“The findings also open up exciting new research avenues that apply similar imaging techniques across a range of mental health conditions, with the aim of developing better early assessments and more targeted treatment tools.”
Similar findings have previously been shown in mouse models and senior author Professor Ray Dolan, also of the UCL Queen Square Institute of Neurology, added: “We are very excited by these findings especially as they build on a set of techniques the group at UCL has developed over the past five years.
“This is the first demonstration of a link between replay and schizophrenia. Replay itself, and its disruption in schizophrenia, provides a highly plausible neurophysiological rationale for explaining core symptoms of the disorder in a way that has previously proved elusive.”
Neural replay of inferred relationships in schizophrenia. Cell 30 June 2021; doi: 10.1016/j.cell.2021.06.012.
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