SUMMARY

In order to draw a closer connection between spatial memory and hippocampal long-term potentiation (LTP), the activity of a place cell that fires selectively when an animal is located in a certain area of a maze was examined in freely behaving knock-out mice that exhibit spatial learning deficit and altered hippocampal plasticity. This approach seeks to examine the effects of altered synaptic plasticity on the information coding mechanism by characterizing firing properties of certain hippocampal neurons directly underlying perception and memory. Available recording data indicated that synaptic plasticity in the hippocampus is not an essential mechanism for the formation of place selective firing of hippocampal pyramidal neurons, but is important for fine tuning and stabilizing its neural activity across time.

Together with genetic, pharmacologic, and in vitro electrophysiologic studies, this type of approach should allow us to examine whether experimental manipulations that block LTP change the capacity of neurons to process critical sensory stimuli and to code relevant cues into memory, and thus should provide a unique and promising avenue in bringing further insight into the cellular and physiologic mechanisms underlying learning and memory.

Introduction

A major focus of neuroscience research, and the central topic of this volume, is the identification of cellular and molecular plasticity mechanisms that mediate memory. Most studies aimed at this goal involve attempts to relate physiologic or molecular indices of neural plasticity to behavioral performance in learning and memory tests.