Fig 1.

This is Tulving's conceptualization of human memory in the serial parallel independent (SPI) model. Three memory systems representing the perceptual representation system (PRS), semantic, and episodic memory are related in a hierarchical fashion during encoding, where information processing is Serial. Storage of memories is Parallel in each system, and these can be retrieved Independently. Of interest during anaesthesia is the PRS, the lowest ‘rung’ of the model (sensation). If any memory function operates during anaesthesia, it would be the PRS. It is likely that any perceptual (or sensate) memories would be stored in secondary sensory association cortices.