The third edition of this monograph continues to have the goal of providing an overview of current thought about the spinal cord mechanisms that are responsible for sensory processing. We hope that the book is of value to both basic and clinical neuroscientists. Several changes have been made in the presentation, as well as additions because of the research advances that have been made during the past decade. Chapters 3 and 4 in the previous edition have been subdivided, and now the morphology of primary afferent neu rons of the dorsal root ganglia is described in Chapter 3 and the chemical neuroanatomy 4. The description of the dorsal hom in the previous Chapter 4 of these neurons in Chapter is now included in Chapter 5, and the chemical neuroanatomy of the dorsal hom in Chapter 6. Furthermore, discussions of the descending control systems have now been of Chapter 12. consolidated at the end The authors would like to express their appreciation for the help provided by several individuals. R.E.C. wishes to acknowledge the many things he learned about primary afferent neurons from conversations with Dr S. N. Lawson. He also thanks Lyn Shilling for her assistance with the typing. WDW thanks Dr Nada Lawand for her critical reading of parts of the manuscript, Rosaline Leigh for help with the manuscript, and Griselda Gonzales for preparing the illustrations.

The third edition of this monograph continues to have the goal of providing an overview of current thought about the spinal cord mechanisms that are responsible for sensory processing. We hope that the book is of value to both basic and clinical neuroscientists. Several changes have been made in the presentation, as well as additions because of the research advances that have been made during the past decade. Chapters 3 and 4 in the previous edition have been subdivided, and now the morphology of primary afferent neu rons of the dorsal root ganglia is described in Chapter 3 and the chemical neuroanatomy of these neurons in Chapter 4. The description of the dorsal horn in the previous Chapter 4 is now included in Chapter 5, and the chemical neuroanatomy of the dorsal horn in Chapter 6. Furthermore, discussions of the descending control systems have now been consolidated at the end of Chapter 12. The authors would like to express their appreciation for the help provided by several individuals. R.E.C. wishes to acknowledge the many things he learned about primary afferent neurons from conversations with Dr S. N. Lawson. He also thanks Lyn Shilling for her assistance with the typing. WDW thanks Dr Nada Lawand for her critical reading of parts of the manuscript, Rosaline Leigh for help with the manuscript, and Griselda Gonzales for preparing the illustrations.

This monograph thoroughly examines the latest theory and research concerning spinal cord mechanisms of sensory processing. The book begins with a historical review of the organization of the peripheral nervous system is outlined in terms of sensory receptors and primary afferent axons. The authors examine the dorsal horn and the structure and function of dorsal horn internurons, and neurophysiological evidence concerning the location of sensory pathways in the spinal cord white matter. After te dorsal column, dorshlateral fasciculus, and the ventral quadrant are covered, the final chapter summarizes knowledge on receptors and spinal cord pathways of various sensations, including touch-pressure, flutter-vibration, pain, temperature, position sense, visceral sensation, and descending control systems.

As stated in the preface to the first edition, the goal of this monograph is to provide an overview of current thought about the spinal cord mechanisms responsible for sensory processing. We hope that the book will be of value to both basic neuroscientists and clinicians. The organization of the monograph has followed the original plan in most respects, although the emphasis has changed with respect to many topics because of recent advances. In particular, a substantial increase in the number of investigations of the dorsal root ganglion has led us to devote a chapter to this topic. The treatment of chemical neuroanatomy in the dorsal horn, as well as the relevant neuropharmacology, has also been expanded considerably. Another major emphasis is on the results of experiments employing microneurography in human subjects. We thank Margie Watson and Lyn Schilling for their assistance with the typing and Griselda Gonzales for preparing the illustrations.

Traumatic injury of the spinal cord affects the entire organism directly and indirectly. Primary injury destroys neurons and severs axons which participate in neural circuits. Secondary injuries and pathologies arise from numerous sources including systemic inflammation, consequential damage of cutaneous, muscular, and visceral tissues, and dysregulation of autonomic, endocrine and sensory- motor functions. Evidence is mounting that spinal cord injury (SCI) affects regions of the nervous system spatially remote from the injury site, as well as peripheral tissues, and alters some basic characteristics of primary afferent cell biology and physiology (cell number, size/frequency, electrophysiology, other). The degree of afferent input and processing above the lesion is generally intact, while that in the peri-lesion area is highly variable, though pathologies emerge in both regions, including a variety of pain syndromes. Primary afferent input to spinal regions below the injury and the processing of this information becomes even more important in the face of complete or partial loss of descending input because such spared sensory processing can lead to both adaptive and pathological outcomes. This issue hosts review and research articles considering mechanisms of plasticity of primary afferent neurons and sensory processing after SCI, and how such plasticity contributes to sparing and/or recovery of functions, as well as exacerbation of existing and/or emergent pathologies. A critical issue for the majority of the SCI community is chronic above-, peri-, and below-level neuropathic pain, much of which may arise, at least in part, from plasticity of afferent fibers and nociceptive circuitry. For example, autonomic dysreflexia is common hypertensive syndrome that often develops after SCI that is highly reliant on maladaptive nociceptive sensory input and processing below the lesion. Moreover, the loss of descending input leaves the reflexive components of bladder/bowel/sexual function uncoordinated and susceptible to a variety of effects through afferent fiber plasticity. Finally, proper afferent feedback is vital for the effectiveness of activity-dependent rehabilitative therapies, but aberrant nociceptive input may interfere with these approaches since they are often unchecked due to loss of descending modulation.

This book constitutes the proceedings of a NATO Advanced Research Workshop held in El Escorial (Spain) from 22 -27 May 1988 with the title Processing of sensory information in the superficial dorsal hom of the spinal cord. Included in the book are reports of most of the main lectures given at the meeting, section introductions written by each session Chairman, section reports compiled by session rapporteurs and some short papers invited from authors of communications given in poster form. The latter were selected on the basis of being immediately relevant to the topic of the workshop and of originating from a laboratory not represented by the main speakers. All in all we believe that the reader can get a fair idea of the structure and general character of this Workshop. The overall aim of the meeting was to review the current state of knowledge on the role of the superficial dorsal horn of the mammalian spinal cord as a nucleus of relay and modulation of the somatic and visceral sensory input to the central nervous system. In this context, the contribution of this spinal cord region to the appreciation of pain was a central topic of discussion. Over the last decade there has been a considerable increase in anatomical, physiological and neurochemical studies of the superficial dorsal horn.