I would like first to thank Charles Woody and his organizing committee for arranging the symposium on the "Cellular Mechanisms of Conditioning and Behavioral Plasticity," which was also a satellite meeting of the International Union of Physiological Sciences 30th International Congress. The proceedings of this symposium are represented by the chapters that follow. During the 1970s, Dr. Woody and co-workers were able to carry out a remarkable series of microelectrode studies, both intracellular and extracellular, of cortical nerve cells during conditioning of the eye-blink response to sound in the intact waking cat. He demonstrated enduring changes in excitability and membrane resistance in pericruciate cortical cells during associative conditioning of the eye blink, changes that are facilitated by ACh and cGMP and reinforced by stimulation of the hypothalamus (the latter con firming the original studies of Voronin). These findings have been of considerable im portance in our attempt to understand the conditioning process at the cellular level.

The electrical and synaptic neuronal activity within the brain is altered when animals acquire new information about their environment. During classical olfactory conditioning, for example, the conditioned stimulus gains a new value by being rewarded. This process correlates with modulations of cell physiology in some of those neurons that are involved in odor processing and odor learning. Physiologists aim to identify the mechanisms underlying learning-dependent cellular plasticity. Ionic currents and transmitter receptors as well as their cellular consequences are investigated. In honeybees, the cellular physiology of olfactory learning is well described, and models of some of the neural mechanisms of learning are established. This chapter surveys how the properties of voltage- and ligand-gated ionic currents and metabotropic receptors of honeybee neurons fit into a model of cellular plasticity underlying appetitive odor learning in the honeybee.

This is the second volume to be based on a series of symposia being held periodically on the neurobiology of conditioning. The first, entitled Conditioning: Representation of Involved Neural Functions was based on a symposium held in Asilomar, Cali fornia, in October 1982 (Woody, 1982). The present volume is based on a sym posium, organized by D. Alkon and C. Woody, held at the Marine Biological Laboratory in Woods Hole, Massachusetts in November 1983. This series of sym posia and their publication are more than justified by the extraordinary progress be ing made during recent years in all branches of neuroscience and its application to our understanding of some of the basic neuronal mechanisms of conditioning and learning. Invertebrate models of conditioning have been used by many in the attempt to obtain a more thoroughly controlled analysis at the single cellular and synaptic level of the mechanisms involved in elementary conditioning in a simple nervous system. Examples of this approach are presented in this volume and utilize insects (grasshopper), crustacea (crayfish), and particularly the relatively simple nervous systems of mollusks (Aplysia and Hermissenda). In such preparations it is possible to carry out precise electrophysiological and neurochemical studies of single iden tified cells and synapses involved in such simple processes as habituation and sensitization, as well as simple forms of "associative" conditioning, usually using simple aversive or withdrawal reflexes.

Although classical and operant conditioning are operationally distinct, it is unclear to what extent they are mechanistically similar or different. Feeding behavior in the mollusk Aplysia californica is a useful model system to analyze these two ubiquitous forms of associative learning and compare the underlying neuronal mechanisms. Here, we review studies that have analyzed and compared the mechanisms underlying classical and operant conditioning at the circuit, single-cell, and molecular levels. These analyses reveal similarities and intriguing differences. Both forms of learning lead to increased biting in vivo and fictive ingestion in vitro and also share a common reinforcement pathway, which uses dopamine as the reinforcement transmitter. Although the identified neuron B51 is a locus of plasticity common to both classical and operant conditioning, its activity is altered in opposite ways by these two forms of learning. B51 excitability is increased by operant conditioning, whereas it is decreased by classical conditioning.

Advances in Physiological Sciences, Volume 36: Cellular Analogues of Conditioning and Neural Plasticity is a collection of paper that details the various aspects of neural plasticity from various methodological perspectives. The title covers the physiological–morphological and biochemical methods in studying neural plasticity. The coverage of the text includes topics such as neuroplasticity in the superior cervical ganglion as a consequence of long-lasting inhibition; evidence for remodeling of synaptic contacts in muscles of adult frog; and calcium and presynaptic factors in synaptic plasticity. The selection also covers the regulation of acetylcholine receptors; molecular mechanisms of sensitization and desensitization of ß-receptors connected with adenylate cyclase; and cellular and behavioral studies of learning and memory in simpler systems. The book will be of great use to neurologists, neurosurgeons, and behavioral scientists.

Lymnaea provides highly valuable experimental models for top-down analyses of associative learning and memory. Using classical conditioning paradigms, molecular mechanisms of consolidation, maintenance, retrieval, and reconsolidation of associative memory have been investigated. Long-term memory (LTM) forms after multitrial reward and aversive conditioning but, unusually, also after single-trial reward conditioning (“flashbulb memory”). Molecular mechanisms of LTM involve highly conserved signaling pathways (NO/cGMP, cAMP/PKA, MAPK, NMDA receptors, and CaMKII), transcriptional regulation of gene expression by CREB and C/EBP, and new protein synthesis. Cellular mechanisms of LTM involve synaptic or nonsynaptic plasticity in key modulatory interneurons of the feeding network. Importantly, a number of molecular processes involved in LTM have been traced from the behavioral level to single identified neurons.

Focus here is on the molluscan neurone. Contributors describe the biochemical regulation of neuronal excitability; control of regeneration and synapse formation by adult molluscan neurones; behavioral plasticity in adult molluscs; the role of second messengers and protein kinases; molluscan behavior and aging, and its modulation by peptides. Distributed in the US by St. Martins Press. Acidic paper. Annotation copyrighted by Book News, Inc., Portland, OR