Sleep and memory
Historical Background and Sleep Cycles: – David Hartley’s suggestion in 1801 about dreaming altering brain links. – Acceptance of the idea of sleep sorting memories […]
Historical Background and Sleep Cycles:
– David Hartley’s suggestion in 1801 about dreaming altering brain links.
– Acceptance of the idea of sleep sorting memories in the 19th century.
– Categorization of sleep stages in 1953 leading to memory studies.
– Progression of sleep through five stages in a 90-110 minute cycle.
– EEG measures brain activity in different sleep stages.
Memory Processes and Terms:
– Stabilization, enhancement, use-dependent, and experience-dependent processes.
– Consolidation encoding memories in a sturdy manner facilitated by sleep.
– Reconsolidation involving retrieving memories into short-term memory.
– Impact of reconsolidation on explicit and implicit memories.
Effects of Sleep Deprivation on Memory:
– Post-training vs. pre-training sleep deprivation studies on memory.
– Crucial understanding of memory processing in relation to sleep deprivation.
– Impact of sleep timing on memory retention.
– Insights into memory consolidation from different approaches.
Memory Measurement Techniques:
– Behavioral measures like self-ordered pointing and mirror tracing tasks.
– Neural imaging measures such as structural and functional imaging.
– Molecular measures enhancing activation areas indecipherable by neuroimaging.
– Electrophysiological measures like polysomnography for analyzing sleep patterns.
Memory Consolidation and Cognitive Functions:
– Role of sleep in memory consolidation and enhancement.
– Slow wave sleep (SWS) and REM sleep importance for different memory types.
– Brain activation during tasks related to cognitive functions.
– Effects of sleep deprivation on cognitive functions like attention and memory.
The relationship between sleep and memory has been studied since at least the early 19th century. Memory, the cognitive process of storing and retrieving past experiences, learning and recognition, is a product of brain plasticity, the structural changes within synapses that create associations between stimuli. Stimuli are encoded within milliseconds; however, the long-term maintenance of memories can take additional minutes, days, or even years to fully consolidate and become a stable memory that is accessible (more resistant to change or interference). Therefore, the formation of a specific memory occurs rapidly, but the evolution of a memory is often an ongoing process.
Memory processes have been shown to be stabilized and enhanced (sped up and/or integrated) and memories better consolidated by nocturnal sleep and daytime naps. Certain sleep stages have been demonstrated as improving an individual's memory, though this is task-specific. Generally, declarative memories are believed to be enhanced by slow-wave sleep, while non-declarative memories are enhanced by rapid eye movement (REM) sleep, although there are some inconsistencies among experimental results. The effect of sleep on memory, especially as it pertains to the human brain, is an active field of research in neurology, psychology, and related disciplines.