We have simulated the brain mechanisms involved in semantic processing tasks such as the differentiation of two sequential stimuli based upon recalled semantic features. In this paper we examine the relationship between perceptual inputs, working memory and semantic memory in these tasks. We propose that phase synchronous firing binds features in semantic memory with concepts in working memory, and that a phase comparison mechanism subserves the process of response selection. The model is consistent with the anatomy and physiology of the component brain circuits where known. This research is important because the relationship between working memory and long-term memory is a central component of many theories of cognition.

Recent Positron Emission Tomography (PET) and other studies have produced detailed information about the areas of the brain involved in word association tasks, their functional roles in learning word associations, and the changes in activity in these areas during learning. We present a dynamic neurond model that replicates observed human cognitive behavior in learning word as?sociations while satisfying salient neuroanatomical and neuropsychological constraints. The model captures the observed dynamics of cortico-thalamo-basal ganglionic loops.