http://muse.jhu.edu/journals/perspectives_in_biology_and_medicine/v047/47.2tsonis.pdf

In the 2004 article, “A ‘Small-World’ Network Hypothesis for Memory and Dreams,” which appeared in the journal, Perspectives in Biology and Medicine, Panagiotis Tsonis links the small world phenomenon with memory processes in the brain. Citing the hypotheses of Watts and Strogatz that the connections between neurons create small-world networks, Tsonis suggests that memory associations similarly form small world networks, with each separate memory representing a different node in the model. Tsonis describes how memories are associated with the events and environment surrounding their formation, and how exposure to similar surroundings can trigger a cascade of stored memories leading to a seemingly irrelevant recollection. The article further relates the small world hypothesis to dreaming, noting that during sleep, memory consolidation occurs. During non-REM ( “hypnagogic” ) sleep, instances experienced throughout the day are incorporated into the long-term memory, while during deeper, REM sleep, more incoherent, stressful thought-processing and dreaming occurs. Tsonis posits that there are 2 network models involved in dreaming: a small-world, memory-association network that constructs the long-term memory during non-REM, conscious dreaming and a more random model of activated thoughts/memories during REM dreaming.

This article relates to our class discussion of the small-world phenomenon. Originating with the work of psychologist Stanley Milgram and his 1967 letter-targeting experiments (which gave rise to the phrase, “six degrees of separation”), the phenomenon shows how an apparently clustered, localized set of nodes (or people) with few long-range connections can be remarkably interconnected. This article extrapolates the concept to thought-processing and memory formation, suggesting that just as people are linked in a small-world network model, so too are memories. Furthermore, Tsonis suggests that these ordered memory networks are constructed during non-REM dreaming, as opposed to the more random thought models which occur during REM dreaming.