The Limbic System

While this book is intended to be an introduction to the neuroanatomy of the limbic system and to studies of the behavior of animals in which the limbic system is stimulated or damaged, it is primarily intended for advanced students of brain-behavior relationships. I have assumed the reader to have some under­ standing of the structure of the brain, of basic neurophysiology, and of modern behavioral techniques. It has been written for students in graduate programs in psychobiology, physiological psychology, and the neurosciences, but it also should be of interest to some medical students and to others with catholic interests in the biology of behavior. In the first chapter, I review the structure of the limbic system and in subsequent chapters consider the behavioral effects of lesions and stimulation of components of the limbic system. Supplement information derived from recording the electrical signals of the brain is included where it seems appropriate. The final chapter presents a perspective of the limbic system related to brain stem mechanisms and the neocortex. Understanding the behavioral contributions of the limbic system presupposes under­ standing how the limbic system interacts with other systems of the brain. v Preface vi Even though there is only one chapter overtly devoted to theoretical issues. various biases of mine influence all chapters. Anyone reading the book with a critical attitude will soon be aware of them. I would like to alert the reader to some of them ahead of time.

1 The Structure of the Limbic System.- The Limbic System in Nonmammals.- The Question of Homology.- The Hypothalamus.- The Amygdala.- The Hippocampus.- The Septal Area.- Limbic System-Midbrain Relations.- 2 The Hypothalamus.- Pleasurable Reactions.- The Location of Pleasure Regions.- Pain and Punishment.- The Location of Pain Regions.- Elicited Behaviors.- Relations with the Autonomic Nervous System.- Lesions of the Lateral Hypothalamus.- Ventromedial Hypothalamic Lesions.- Selective Lesions in the Hypothalamus.- Neurochemical Systems.- The Neurochemistry of Eating.- The Neurochemistry of Behavioral Suppression.- The Mammillary Bodies, the Mammillothalamic Tract, and the Cingulate Cortex.- Reflections and Summary.- 3 The Amygdala.- General Effects Produced by Amygdala Stimulation or Lesions.- Studies of Learning and Memory.- Transfer and Transposition.- Reflections and Summary.- 4 The Septal Area.- General Changes Following Septal Lesions.- Changes in Performance on Learning Tasks After Septal Lesions-Avoidance Behaviors.- Response Inhibition in Appetitive Tasks.- Electrical Stimulation of the Septal Area.- Autonomic Effects Produced by Septal Stimulation.- Neurochemical Considerations.- Reflections and Summary.- 5 The Hippocampus.- General Changes Produced by Hippocampal Damage.- Studies of Learning and Memory-Avoidance Conditioning.- Learning in Appetitive Tasks.- Frustration.- Regional Differences Within the Hippocampus.- Electrical Rhythms of the Hippocampus.- Summary and Reflections.- 6 The Graven Image, Lethe, and the Guru.- The Triune Brain.- The Neocortex: The Guru.- References.- Author Index.