Contents xiii Central Control of Visceral Motor Functions 483 Visceral motor reflex Functions 491 Box A The Hypothalamus 484 Autonomic Regulation of Cardiovascular Function 491 Neurotransmission in the Visceral Motor System 487 Autonomic Regulation of the Bladder 493 Box B Horners Syndrome 488 Autonomic Regulation of Sexual Function 496 Box c obesity and the Brain 490 Summary 498 Unit/V THE CHANGING BRAIN Chapter 21 Early Brain Development 501 Box B Molecular Signals That Promote Synapse Overview 501 Formation 542 The Initial Formation of the Nervous System Trophic Interactions and the Ultimate Size of Neuronal Gastrulation and Neurulation 501 Populations 543 The Molecular Basis of Neural Induction 503 Further Competitive Interactions in the Formation of BOx A Stem Cells: Promise and Perils Neuronal Connections 545 504 BoX B Retinoic Acid: Teratogen and Inductive Molecular Basis of Trophic Interactions 547 Box C Why Do Neurons Have Dendrites?548 Formation of the major Brain Subdivisions 510 Box D The Discovery of BDNF and the Box C Homeotic Genes and Human Brain Neurotrophin Family 552 evelopment 513 neurotrophin Signaling 553 Box D Rhombomeres 514 Summary 554 Genetic Abnormalities and Altered Human brain Development 515 Chapter 23 Modification of Brain Circuits The Initial Differentiation of Neurons and Glia 516 as a Result of Experience 557 Box E Neurogenesis and Neuronal Birthdating Overview 557 517 Critical Periods 557 The Generation of Neuronal Diversity 518 Box A Built-In Behaviors 558 Neuronal Migration 520 The Development of Language Box F Mixing It Up: Long-Distance Neuronal Example of a Human Critical Period 559 Migration 524 Box B Birdsong 560 Summary 525 Critical Periods in Visual System Development 562 Effects of Visual Deprivation on Ocular Dominance 563 Chapter 22 Construction of Neural Box C Transneuronal Labeling with Radioactive Circuits 527 Amino Acids 564 Overview 527 isual Deprivation and Amblyopia in Humans 568 The Axonal Growth Cone 527 Mechanisms by which Neuronal Activity Affects the Non-Diffusible Signals for Axon Guidance 52 Development of Neural Circuits 569 Box A Choosing Sides: Axon Guidance at the Cellular and Molecular Correlates of Activity Optic Chiasm 530 Dependent Plasticity during Critical Periods 572 Chemoattraction and Repulsion ce Diffusible Signals for Axon Guidar Evidence for Critical Periods in Other Sensor 534 The Formation of Topographic Maps 537 Summary 573 Selective Synapse Formation 539Chapter 21 Early Brain Development 501 Overview 501 The Initial Formation of the Nervous System: Gastrulation and Neurulation 501 The Molecular Basis of Neural Induction 503 BOX A Stem Cells: Promise and Perils 504 BOX B Retinoic Acid: Teratogen and Inductive Signal 506 Formation of the Major Brain Subdivisions 510 BOX C Homeotic Genes and Human Brain Development 513 BOX D Rhombomeres 514 Genetic Abnormalities and Altered Human Brain Development 515 The Initial Differentiation of Neurons and Glia 516 BOX E Neurogenesis and Neuronal Birthdating 517 The Generation of Neuronal Diversity 518 Neuronal Migration 520 BOX F Mixing It Up: Long-Distance Neuronal Migration 524 Summary 525 Chapter 22 Construction of Neural Circuits 527 Overview 527 The Axonal Growth Cone 527 Non-Diffusible Signals for Axon Guidance 528 BOX A Choosing Sides: Axon Guidance at the Optic Chiasm 530 Diffusible Signals for Axon Guidance: Chemoattraction and Repulsion 534 The Formation of Topographic Maps 537 Selective Synapse Formation 539 BOX B Molecular Signals That Promote Synapse Formation 542 Trophic Interactions and the Ultimate Size of Neuronal Populations 543 Further Competitive Interactions in the Formation of Neuronal Connections 545 Molecular Basis of Trophic Interactions 547 BOX C Why Do Neurons Have Dendrites? 548 BOX D The Discovery of BDNF and the Neurotrophin Family 552 Neurotrophin Signaling 553 Summary 554 Chapter 23 Modification of Brain Circuits as a Result of Experience 557 Overview 557 Critical Periods 557 BOX A Built-In Behaviors 558 The Development of Language: Example of a Human Critical Period 559 BOX B Birdsong 560 Critical Periods in Visual System Development 562 Effects of Visual Deprivation on Ocular Dominance 563 BOX C Transneuronal Labeling with Radioactive Amino Acids 564 Visual Deprivation and Amblyopia in Humans 568 Mechanisms by which Neuronal Activity Affects the Development of Neural Circuits 569 Cellular and Molecular Correlates of Activity￾Dependent Plasticity during Critical Periods 572 Evidence for Critical Periods in Other Sensory Systems 572 Summary 573 Contents xiii Unit IV THE CHANGING BRAIN Central Control of Visceral Motor Functions 483 BOX A The Hypothalamus 484 Neurotransmission in the Visceral Motor System 487 BOX B Horner’s Syndrome 488 BOX C Obesity and the Brain 490 Visceral Motor Reflex Functions 491 Autonomic Regulation of Cardiovascular Function 491 Autonomic Regulation of the Bladder 493 Autonomic Regulation of Sexual Function 496 Summary 498 Purves3/eFM 5/13/04 12:59 PM Page xiii