The thalidomide tragedy which occurred slightly more than a decade ago made public officials and the general public acutely aware of the teratogenic potential of drugs. Although specialists in pharmacology and developmental biology had been studying this problem many years before, this catastrophic episode triggered the passage of legislation which required that information about the teratogenicity of drugs be produced before the drugs could be available to the general public. Gross deformities in man produced by drugs are frequently difficult to reproduce in experimental animals and the changes which are produced in other animals are frequently not translatable to humans. The problem of evaluating the potential that drugs have to produce gross malformations is small, however, compared to the evaluation of subtle but permanent behavioral effects which drugs may exert upon the developing organism. Nevertheless, many experimental studies in recent years indicate that subtle biochemical changes produced by drugs on brain tissue during critical periods of fetal or early post­ natal maturation may become manifest subsequently as behavioral deviations in early childhood or adolescence. Hyperkinetic disorders, epilepsies and other developmental disabilities may have a subtle biochemical imbalance, perhaps drug induced, as an underlying factor. This symposium was organized with the intent of bringing to­ gether prominent investigators who are working in different aspects of brain development and who are interested in the effects of drugs on the developing brain in order to discuss their findings, pro­ pose new theories, and open new avenues for future research.

CNS Drugs: Functional Development.- Development of Synaptic Substrates for Drug Actions in Immature Brain.- Selective Depression of Organotypic Bioelectric Activities of CNS Tissue Cultures by Pharmacologic and Metabolic Agents.- CNS Drugs: Behavioral Development.- Factors Influencing the Effects of Drugs Administered During Development on Adult Behavior.- Gonadal Hormones and the Developing Brain.- Postnatal Behavioral Effects of In Utero Exposure to Drugs Which Modify Catecholamines and/or Serotonin.- Developmental Aspects of Neurotransmission.- Neurotransmitter Systems in the Central Nervous System.- Uptake and Storage of 3H-Norepinephrine in the Cerebral Hemispheres and Cerebellum of Chicks During Embryonic Development and Early Posthatching.- Studies on the Development of Tyrosine Hydroxylase, Monoamine Oxidase and Aromatic-L-Amino Acid Decarboxylase in Several Regions of the Chick Brain.- Prenatal Exposure to Drugs: Effect on the Development of Brain Monoamine Systems.- Chromogranins and Neurotransmitter Retention During Development of the Adrenergic Neuron.- Drug Actions: Biochemical Development: (Enzymes, Amino Acids, Proteins and Nucleic Acids).- Alterations of Protein Metabolism During Development of the Brain.- Free Amino Acids in the Developing Brain as Affected by Drugs.- Effects of Prenatal and Postnatal Nicotine Administration on Biochemical Aspects of Brain Development.- Drug Actions: Biochemical Development: (Electrolytes, Acid-Base).- Maturation of the Blood-Brain and Blood-CSF Barriers.- Changes in CSF Flow and Extracellular Space in the Developing Rat.- Developmental Changes in Ionic Composition of the Brain in Hypo and Hyperthyroidism.- Some Aspects of Acid-Base Metabolism in the Immature Central Nervous System.- Developmental Aspects of Learning and Memory.- The Development of Behavior in Normal and Brain-Damaged Infant Rats, Studied with Homing (Nest-Seeking) as Motivation.- Drug Actions: Myelinogenesis.- Proteolipids.- Protein and Enzyme Changes with Brain Development.- The Morphology of the Developing Myelin Sheath.- Environment, Hormones: Brain Development.- Developmental Changes in the Responsivity of the Brain to Endogenous and Exogenous Factors.- Effects of Hypoxic Environment on Prenatal Brain Development: Recent Evidence Versus Earlier Dogma.- Thyroid Hormones in Relation to Development of the Nervous System.- Therapeutics.- Neuropharmacology of Hyperkinetic Behavior: Response to Methylphenidate Correlated with Degree of Activity and Brain Damage.- Occult Mechanisms of Brain Development.- Management of Seizure Disorders in Infancy, Childhood and Adolescence.- Participants.