Samsonovich, Alexei
Coauthors(s): Lynn Nadel, Psychology, University of Arizona, Tucson AZ 85721-0068. Morris Moscovitch, University of Toronto, Toronto, Ontario, Canada.
University of Arizona
Psychology
Psychology Bldg. Room 314, University of Arizona, Tucson AZ 85721-0068
www.nsma.arizona.edu/alexei/

A Theory-of-Mind Connectionist Model of Episodic Memory Consolidation

Traditionally, semantic memory is understood as general world knowledge, which is not referenced to specific episodes and is therefore context-free. In contrast, an episodic memory is traditionally viewed as context-specific and rich in details. According to an alternative interpretation of this dichotomy (Wheeler, Stuss & Tulving, 1997), episodic memory retrieval involves mental simulation of a previously experienced mental state. On the other hand, semantic memory retrieval may involve objective thinking about the past, but not re-experiencing a previous mental state. In this work we design and study an abstract connectionist model based on the concept of a mental state (borrowed from theory-of-mind studies) and its plausible instantiation in the brain. A mental state is understood here as an ensemble of working memory representations, attributed to a particular source token agent, which we call a determinant of a mental state. We limit our consideration to the case where a determinant is either the current instance of the self or one of its past instances. Determinants are assumed to be represented in the hippocampus and in the prefrontal cortex. Computer simulation of the model is shown to be capable of reproducing the normal process of episodic memory consolidation as well as selected cases of its pathology. Mapping the model components onto brain neuroanatomy allows us to account for major well-documented facts about episodic and semantic memory disorders caused by localized brain damage (e.g., Vargha-Khadem et al., 1997). Therefore our results relate the studies of hippocampal amnesia to the studies of human theory of mind and metacognition. Supported by the Consciousness Studies Research Grant from the University of Arizona.