Introduction

The aim of this chapter is to try to bring together some of the recent advances in the study of the neural substrates of fear and anxiety in laboratory animals to form a coherent overview that will facilitate comparisons between these basic studies and clinical investigations. The advances made in the study of animal models of anxiety over the past decade are little short of remarkable, especially in the field of conditioned fear. We may now with some confidence map out likely neural mechanisms from the level of functional systems to the cellular and molecular details. We know much of which neuroanatomical areas, neural projections, neurotransmitter systems and receptors are involved in the acquisition and expression of a number of fear-related behaviours.

This is fine progress indeed, but often begs the question of direct relevance to clinical applications. To what extent is the study of conditioned fear and anxiety in animals easily translated into the neuropsychiatric domain? There are several approaches to answering this question. One might suggest that clinical anxiety does indeed reflect a specific neuropathology in a specific behavioural system that is well described at the neurobiological and behavioural level (e.g. patterns of defensive behaviour; Rodgers 1997). This approach values certain forms of animal model over others (e.g. ethological vs. conditioning-based models), and to a certain degree adheres to the suggestion that anxiety reflects a pathological state of a perfectly normal fear system.