THE MODULATION OF LEARNING STATE IN A BIOLOGICAL ASSOCIATIVE MEMORY -AN IN-VITRO, IN-VIVO, AND IN COMPUTO STUDY OF OBJECT RECOGNITION IN MAMMALIAN OLFACTORY CORTEX

During learning of overlapping input patterns in an associative memory , recall of previously stored patterns can interfere with the learning of new patterns. Most associative memory models avoid this difficulty by ignoring the effect of previously modified connections during lear ning, by clamping network activity to the patterns to be learned. Thro ugh the interaction of experimental and modeling techniques, we now ha ve evidence to suggest that a somewhat analogous approach may have bee n taken by biology within the olfactory cerebral cortex. Specifically we have recently discovered that the naturally occurring neuromodulato r acetylcholine produces a variety of effects on cortical cells and ci rcuits which, when taken together, can prevent memory interference in a biologically realistic memory model. Further, it has been demonstrat ed that these biological mechanisms can actually improve the memory st orage performance of previously published abstract ''neural network'' associative memory models.