MEMORY FROM THE DYNAMICS OF INTRINSIC MEMBRANE CURRENTS

Almost all theoretical and experimental studies of the mechanisms unde rlying learning and memory focus on synaptic efficacy and make the imp licit assumption that changes in synaptic efficacy are both necessary and sufficient to account for learning and memory. However, network dy namics depends on the complex interaction between intrinsic membrane p roperties and synaptic strengths and time courses. Furthermore, neuron al activity itself modifies not only synaptic efficacy but also the in trinsic membrane properties of neurons. This paper presents examples d emonstrating that neurons with complex temporal dynamics can provide s hort-term ''memory'' mechanisms that rely solely on intrinsic neuronal properties. Additionally, we discuss the potential role that activity may play in long-term modification of intrinsic neuronal properties. While not replacing synaptic plasticity as a powerful learning mechani sm, these examples suggest that memory in networks results from an ong oing interplay between changes in synaptic efficacy and intrinsic memb rane properties.