The Center for Sleep and Cognition (and before that, the Laboratory of Neurophysiology) has been at the forefront of investigations into the role of sleep in learning and memory consolidation. In our published work, we have provided clear demonstrations, and in many cases the first such demonstration, that:
- Some forms of memory consolidation are absolutely dependent on post-training sleep.
- Naps can be as effective as a night of sleep for memory consolidation and can reverse daytime task-specific fatigue.
- Sleep can enhance the memory of emotional elements within pictures, while allowing memory of other aspects of the pictures to deteriorate.
- Sleep can enhance memory for the gist of an experience, while allowing the details to deteriorate.
- Sleep can extract the rules that explain previous complex experiences.
- Access to associative memories is altered during REM sleep.
- Sleep induces changes in the brain regions activated during the performance of previously learned skills.
- Sleep deprivation prior to learning leads to the preferential retention of memories with negative emotional tone.
- Memory reconsolidation can be blocked in humans by introducing competing memories.
- Charles Bonnet syndrome, a visual disorder with hallucinations, can be induced by visual deprivation.
- Patients with sleep apnea fall to show normal sleep-dependent improvement on both procedural and declarative memory tasks.
- Patients addicted to cocaine fail to show normal sleep-dependent improvement on motor and perceptual skill tasks during withdrawal, despite showing normal improvement during periods of drug use.
- Chronic, medicated schizophrenia patients show deficits in sleep-dependent improvement on a motor task, a deficit that is correlated with deficits in sleep spindles
- Chronic medicated schizophrenia patients show sleep spindles deficits of as much as 40%.
- Sleep spindle deficits are also seen in early course, antipsychotic medication-naïve schizophrenia patients, as well as in first-degree relatives of schizophrenia patients.
- Hypnagogic dreams are constructed without the help of the hippocampally mediated episodic memory system, can replay events of the day in abstracted but recognizable forms.
- Dreaming about a recently learned task predicts enhanced sleep-dependent memory consolidation.
These studies, published in journals including The Journal of Cognitive Neuroscience, Nature, Nature Neuroscience, Neuron, Biological Psychiatry, Current Biology and Science, have contributed to a new and exciting understanding of the role of sleep and dreaming in memory processing.