Aging and Recovery of Function in the Central Nervous System

The mammalian central nervous system is a remarkable structure which has attracted many new investigators, as evidenced by the dramatic increase in scientific publications dealing with neurobiology. Every day basic scientists conduct new and exciting experiments, resulting in remarkable discoveries des­ tined to help mankind. Unfortunately many of these new findings are slow to be accepted by the clinical world. This is especially true in the area of brain trauma, where the present prognosis is usually very poor. We have known for quite some time that the mammalian central nervous system is capable of compensating for severe damage in many different ways, and under some circumstances behav­ ioral compensation can be observed. However, much is still to be learned about the various factors and events that lead to functional recovery and those condi­ tions that do not. It is this challenge that originally excited a number of the contributors to this volume to explore the subject of recovery from brain damage. One factor in particular that is known to change the prognosis of recovery is the age of the organism at the time of the damage. This book is an attempt to explore this important variable. Most of the literature concerning aging deals with widespread degenerative changes and paints a grim picture for the aging central nervous system in terms of recovery of function following trauma.

1 Longevity, Disease, and Autoimmune Reactions following Focal Cortical Injuries.- 1. Introduction.- 2. Longevity.- 3. Disease Profiles.- 4. Neuron-Binding Antibodies.- 5. Conclusions.- References.- 2 Aging and Hypothalamic Regulation of Metabolic, Autonomic, and Endocrine Function.- 1. Introduction.- 1.1. Theories of Aging.- 1.2. Aging-Related Changes in Behavioral and Physiological Function.- 2. Structure and Function of the Hypothalamus.- 3. Hypothalamic Theories of Aging.- 3.1. Dilman’s Hypothalamic Elevation Theory.- 3.2. Groen’s Hypothalamic Theory.- 3.3. Frolkis’s Hypothalamic Disregulation Theory.- 4. Effects of Hypothalamic Damage.- 4.1. Lateral Hypothalamic Damage.- 4.2. Ventromedial Hypothalamic Damage.- 5. Aging-Hypothalamic Damage Comparisons.- 6. Overview and Summary.- References.- 3 Morphological Measurements in the Aging Rat Cerebral Cortex.- 1. Introduction.- 2. Neuronal and Glial Cell Number Changes during Aging.- 2.1. Dendritic Branching.- 2.2. Dendritic Density.- 2.3. Dendritic Length.- 2.4. Dendritic Spines.- 3. Aging and Impoverishment.- 3.1. Dendrites.- 3.2. Oblique Branching.- 3.3. Oblique Length.- 3.4. Spines.- 4. Summary.- References.- 4 Morphologic Aspects of Brain Damage in Aging.- 1. Introduction.- 2. Reactive Synaptogenesis in Young Adult Animals.- 3. Normal Anatomy of the Aged Hippocampus.- 3.1. Light Microscopic Analysis.- 3.2. Electron Microscopic Analysis.- 4. Reactive Synaptogenesis in the Dentate Gyrus of Aged Animals.- 4.1. Light Microscopic Analysis.- 4.2. Ultrastructural Analysis.- 5. Adrenergic Sprouting in the Limbic System of Aged Rats.- 6. Possible Mechanisms for Reduced Sprouting Capacity.- 7. Conclusion.- References.- 5 Relationship of the Raphe and Suprachiasmatic Nuclei to Serotonin Facilitation of Cyclic Reproductive Functions in Aging Female Rats.- 1. Introduction.- 2. Temporal Patterns of Hypothalamic 5-HT and Cyclic Reproductive Function.- References.- 6 Behavioral Consequences of Neuronal Plasticity following Injury to Nigrostriatal Dopaminergic Neurons.- 1. Introduction.- 2. Approaches to Studying the Neural Events Mediating Behavioral Recovery.- 3. Inattention to Stimuli.- 4. Neglect after Nigrostriatal Injury as a Model System.- 5. Neural Events Contributing to Recovery of Sensorimotor Functions.- 5.1. Basal Gangliar Glucose Utilization.- 5.2. Compensatory Changes at Residual Neostriatal Dopaminergic Synapses and Recovery.- 5.3. Recovery from Nigrostriatal Injury in Senescence.- 5.4. Lithium Effects on Recovery.- 6. Future Directions.- 7. Conclusions.- References.- 7 Do Rats Have Hypotheses? A Developmental and Means-Ends Analyses Approach to Brain Damage, Recovery of Function, and Aging.- 1. Introduction.- 2. Methods.- 2.1. Subjects and Surgery.- 2.2. Behavioral Testing.- 2.3. Histology.- 2.4. Data Analysis.- 3. Results.- 3.1. Qualitative Results.- 3.2. Medial Frontal Lesion Analysis.- 4. Discussion.- References.- 8 Age, Brain Damage, and Behavioral Recovery.- 1. Introduction.- 2. Spatial Alternation Learning.- 2.1. General Methodology.- 2.2. Single-Stage Lesion Effects.- 2.3. Serial Lesion Effect.- 3. Emotional Reactivity.- 4. DRL-20 Performance.- 5. Discussion.- References.- 9 Age and Recovery from Brain Damage: A Review of Clinical Studies.- 1. Functional Plasticity after Early Brain Injury.- 1.1. Implications of Ablation Experiments for Recovery in Children: Methodological Issues in Recovery from Brain Injury at Different Ages.- 1.2. Perinatal and Neonatal Injury.- 1.3. Early Lateralized Brain Injury.- 1.4. Diffuse Insult to the Young Brain.- 2. Head Injury through the Lifespan.- 2.1. Incidence.- 2.2. Cause of Head Injury.- 2.3. Risk Factors.- 3. Pathophysiology of Closed-Head Injury in Relation to Age.- 4. Effects of Age on Outcome after Head Injury.- 5. Early and Late Neurobehavioral Effects of Head Injury.- 5.1. Subacute Behavioral Effects after Head Injury in Children.- 5.2. Residual Neuropsychological Sequelae.- 5.3. Residual Behavioral Disturbance after Head Injury in Children.- 5.4. Summary of Research on Recovery after Head Injury.- 6. Directions for Future Research.- References.- 10 Recovery of Function in Senile Dementia of the Alzheimer Type.- 1. Introduction.- 2. Alzheimer’s Disease: The Clinical and Biochemical Problem.- 3. Behavioral Strategies for Cognitive Deficits of Alzheimer’s Disease.- 4. Pharmacologic Intervention in Alzheimer’s Disease.- 5. Cholinergic Systems, Trophic Substances, and Potential Therapies for Alzheimer’s Disease.- 6. Pharmacologic Enhancement of a Trophic Factor Effect.- References.