Synapses, circuits, and the ontogeny of learning.

This article summarizes the proceedings of a symposium organized by Mark Stanton and Pamela Hunt and presented at the annual meeting of the International Society for Developmental Psychobiology. The purpose of the symposium was to review recent advances in neurobiological and developmental studies of fear and eyeblink conditioning with the hope of discovering how neural circuitry might inform the ontogenetic analyses of learning and memory, and vice versa. The presentations were: (1) Multiple Brain Regions Contribute to the Acquisition of Pavlovian Fear by Michael S. Fanselow; (2) Expression of Learned Fear: Appropriate to Age of Training or Age of Testing by Rick Richardson; (3) Trying to Understand the Cerebellum Well Enough to Build One by Michael D. Mauk; and (4) The Ontogeny of Eyeblink Conditioning: Neural Mechanisms by John H. Freeman. Taken together, these presentations converge on the conclusions that (1) seemingly simple forms of associative learning are governed by multiple "engrams" and by temporally dynamic interactions among these engrams and other circuit elements and (2) developmental changes in these interactions determine when and how learning emerges during ontogeny.