GAMMA-FREQUENCY OSCILLATIONS - A NEURONAL POPULATION PHENOMENON, REGULATED BY SYNAPTIC AND INTRINSIC CELLULAR PROCESSES, AND INDUCING SYNAPTIC PLASTICITY

Neurons are extraordinarily complicated devices, in which physical and chemical processes are intercoupled, in spatially non-uniform manner, over distances of millimetres or more, and over time scales of <1 mse c up to the lifetime of the animal. The fact that neuronal populations generating most brain activities of interest are very large-perhaps m any millions of cells-makes the task of analysis seem hopeless. Yet, d uring at least some population activities, neuronal networks oscillate synchronously. The emergence of such oscillations generates precise t emporal relationships between neuronal inputs and outputs, thus render ing tractable the analysis of network function at a cellular level. We illustrate this idea with a review of recent data and a network model of synchronized gamma frequency (>20 Hz) oscillations in vitro, and d iscuss how these and other oscillations may relate to recent data on b ack-propagating. action potentials, dendritic Ca2+ transients, long-te rm potentiation and GABA(A) receptor-mediated synaptic potentials. (C) 1998 Elsevier Science Ltd. All rights reserved.