ABSTRACT
Computational modeling provides an effective means of linking data across different levels of experimental techniques. Currently, extensive physiological and molecular data concerns cellular mechanisms of cholinergic modulation within cortical structures. However, these data have not been extensively linked to the behavioral evidence for a role of acetylcholine in memory function or attentional mechanisms. This chapter describes a computational modeling framework that simultaneously addresses detailed experimental data at both cellular and behavioral levels, providing a means to bridge the gap between experimental data at a cellular level and the behavior of complete organisms (Hasselmo, 1995, 1999). This chapter also provides a description of how the different physiological effects of acetylcholine could interact to alter specific functional properties of the cortex. As a central theme, the chapter focuses on how acetylcholine enhances the response to afferent sensory input while decreasing the internal processing based on previously formed cortical representations. These same circuit-level effects can be categorized with different colloquial terms at a behavioral level, sometimes being interpreted as an enhancement of attention, sometimes as an enhancement of memory encoding. The same regulatory influences on circuit-level dynamics could underlie all these behavioral effects. This chapter first describes the basic change in circuit dynamics and then reviews specific physiological effects of acetylcholine in the context of this framework. Finally, we discuss how the loss of cholinergic modulation shifts network dynamics toward those appropriate for the consolidation of previously
encoded information.
