- parasitic memory hypothesis
- A hypothesis involving the role of spurious memory traces in the mediation of * musical hallucinations. The term parasitic memory was introduced in or shortly before 1983 by the British neuroscientists Francis Harry Compton Crick (1916-2004) and Graeme Mitchison (b. 1944). These authors use the term in the context of their reverse-learning dream-sleep hypothesis, which involves the notion that certain undesirable connections in cerebral cortical networks are removed by a reverse learning mechanism during REM sleep. This reverse learning mechanism is conceptualized as a neural mechanism by means of which memory traces are weakened rather than strengthened during * dream activity. As Crick and Mitchison recapitulate, "We dream in order to forget." Thus the notion of the parasitic memory was introduced to denote an apparently 'useless' memory trace which is accidentally consolidated rather than weakened. The notion of the parasitic memory was taken up in 1992 by the American psychiatrists Matcheri S. Kesha-van et al. as one of a series of explanatory models for the mediation of musical hallucinations. Starting from the observation that musical hallucinations tend to consist of tunes perceived in the past, Keshavan et al. argue that "a musical memory, with its particular propensity to arouse affect, involving widely distributed brain regions, may prove resistant to unlearning." As they conclude, "This may resonate in a neural net producing the experience of a hallucination. The conditions necessary to set such a chain of events in motion remain unclear, but perhaps sensory deprivation and cerebral dysfunction play a role." On the basis of the authors' account, it would seem justified to classify the parasitic memory hypothesis of musical hallucinations as a variant of the * reperception model of hallucinations.ReferencesCrick, F., Mitchison, G. (1983). The function of dream sleep. Nature, 304, 111-114.Keshavan, M.S., Davis, A.S., Steingard, S., Lish-man, W.A. (1992). Musical hallucinations: A review and synthesis. Neuropsychiatry, Neuropsychology, and Behavioral Neurology,5, 211-223.
Dictionary of Hallucinations. J.D. Blom. 2010.