Sleep behaviour and memory consolidation in patients with disorders of consciousness

• Applicant: Professor Dr. Boris Kotchoubey
• Subject Area: Personality Psychology, Clinical and Medical Psychology, Methodology ; General, Cognitive and Mathematical Psychology
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274661900

The presence of sleep-wakefulness cycles is a differential diagnostic criterion marking the transition from coma to Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS). Because a positive effect of sleep on the consolidation of memory traces was found in numerous studies and the mechanisms of the effect are largely known, a question arises whether such beneficial effect of sleep on learning can also be demonstrated in UWS and MCS patients (and if yes, perhaps it can be used in these patients’ rehabilitation). However, to investigate this issue, we had first (1) to describe the physiological structure of sleep in UWS and MCS, as it strongly differs from that in healthy individuals, (2) to elaborate criteria for their sleep scoring, as the extant criteria cannot be applied without adjustment due to the abnormal sleep structure, and (3) to develop specific learning tasks, as the tasks standardly used in sleep/memory experiments cannot be applied in behaviorally non-responsive patients.All these aims have been attained in the first period of this project. Now, in the second phase we plan to test the hypothesis that sleep supports memory consolidation in UWS and MCS. In a within-subject design, patients will be presented three counterbalanced conditions:1 Sleep Condition: Learning Task => 5h interval with sleep => Task Retest2 Wakefulness Condition: Learning Task => 5h interval w/out sleep => Task Retest3 Control Condition: 5h period w/out sleep => Learning Task (no task before the 5h period)The control condition is necessary to disentangle the possible effect of memory consolidation from the effect of therapeutic intervention during wakefulness period. We expect significantly better task performance at retest as compared with the first task presentation in the Sleep Condition. Furthermore, this improvement is expected to correlate with specific sleep components (e.g., spindles) and with the patient’s neuropsychological state.

• DFG Programme: Research Grants
• Co-Investigators: Privatdozentin Susanne Diekelmann, Ph.D.; Dr. Friedemann Müller