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Peripheral Nervous System: The nervous system outside of the brain and spinal cord. The peripheral nervous system has autonomic and somatic divisions. The autonomic nervous system includes the enteric, parasympathetic, and sympathetic subdivisions. The somatic nervous system includes the cranial and spinal nerves and their ganglia and the peripheral sensory receptors.

What is a Nervous System?

JoVE 10838

The nervous system is the collection of specialized cells responsible for maintaining an organism’s internal environment and coordinating the interaction of an organism with the external world—from the control of essential functions such as heart rate and breathing to the movement needed to escape danger.

The vertebrate nervous system is divided into two major parts: the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain, spinal cord, and retina—the sensory tissue of the visual system. The PNS contains the sensory receptor cells for all of the other sensory systems—such as the touch receptors in the skin—as well as the nerves that carry information between the CNS and the rest of the body. Additionally, part of both the CNS and PNS contribute to the autonomic nervous system (also known as the visceral motor system). The autonomic nervous system controls smooth muscles, cardiac muscles, and glands that govern involuntary actions, such as digestion. The vertebrate brain is primarily divided into the cerebrum, cerebellum, and brainstem. The cerebrum is the largest, most anterior part of the brain that is divided into left and right hemispheres. Each hemisphere is further divided into four lobes: frontal, parietal, occipital, and temporal. The outermost layer of the cerebrum is called

 Core: Nervous System

The Parasympathetic Nervous System

JoVE 10839

The parasympathetic nervous system is one of the two major divisions of the autonomic nervous system. This parasympathetic system is responsible for regulating many unconscious functions, such as heart rate and digestion. It is composed of neurons located in both the brain and the peripheral nervous system that send their axons to target muscles, organs, and glands.

Activation of the parasympathetic system tends to have a relaxing effect on the body, promoting functions that replenish resources and restore homeostasis. It is therefore sometimes referred to as the “rest and digest” system. The parasympathetic system predominates during calm times when it is safe to devote resources to basic “housekeeping” functions without a threat of attack or harm. The parasympathetic nervous system can be activated by various parts of the brain, including the hypothalamus. Preganglionic neurons in the brainstem and sacral part of the spinal cord first send their axons out to ganglia—clusters of neuronal cell bodies—in the peripheral nervous system. These ganglia contain the connections between pre- and postganglionic neurons and are located near the organs or glands that they control. From here, postganglionic neurons send their axons onto target tissues—generally smooth muscle, cardiac muscle, or glands. Typic

 Core: Nervous System

The Sympathetic Nervous System

JoVE 10840

The sympathetic nervous system—one of the two major divisions of the autonomic nervous system—is activated in times of stress. It prepares the body to meet the challenges of a demanding circumstance while inhibiting essential body functions—such as digestion—that are a lower priority at the moment.

As a student, you may have had the experience of walking into class and finding a surprise exam that you were not expecting. In the moment of realization, you may sense your gut tighten, your mouth goes dry, and your heart starts to race all of a sudden. These are signs of the sympathetic system taking over in preparation to react. While you may not be in immediate danger, the system has evolved to facilitate immediate reaction to stress or threats: blood is directed away from the digestive system and skin to increase energy supplies to muscles. Furthermore, the heart rate, and blood flow increase, and pupils dilate to maximize visual perception. At the same time, the adrenal gland releases epinephrine into the circulatory system. Your body is now primed to take action, whether that means to swiftly flee from danger or fight whatever threat may be at hand. The sympathetic nervous system can be activated by various parts of the brain, with the hypothalamus playing a particularly important role. Sympathetic instructions from the central

 Core: Nervous System

Three-dimensional Tissue Engineered Aligned Astrocyte Networks to Recapitulate Developmental Mechanisms and Facilitate Nervous System Regeneration

1Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, 2Center for Neurotrauma, Neurodegeneration & Restoration, Michael J. Crescenz Veterans Affairs Medical Center, 3School of Biomedical Engineering, Drexel University, 4Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, 5Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania

JoVE 55848

 Bioengineering

Anatomically Inspired Three-dimensional Micro-tissue Engineered Neural Networks for Nervous System Reconstruction, Modulation, and Modeling

1Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, 2Center for Brain Injury & Repair, Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, 3Center for Neurotrauma, Neurodegeneration & Restoration, Michael J. Crescenz Veterans Affairs Medical Center, 4School of Biomedical Engineering, Drexel University

JoVE 55609

 Neuroscience

Glial Cells

JoVE 10843

Glial cells are one of the two main types of cells in the nervous system. Glia cells comprise astrocytes, oligodendrocytes, microglia, and ependymal cells in the central nervous system, and satellite and Schwann cells in the peripheral nervous system. These cells do not communicate via electrical signals like neurons do, but they contribute to virtually every other aspect of nervous system function. In humans, the number of glial cells is roughly equal to the number of neurons in the brain. Glia in the central nervous system (CNS) include astrocytes, oligodendrocytes, microglia, and ependymal cells. Astrocytes are the most abundant type of glial cell and are found in organized, non-overlapping patterns throughout the brain, where they closely associate with neurons and capillaries. Astrocytes play numerous roles in brain function, including regulating blood flow and metabolic processes, synaptic ion and pH homeostasis, and blood-brain barrier maintenance. Another specialized glial cell, the oligodendrocyte, forms the myelin sheath that surrounds neuronal axons in the CNS. Oligodendrocytes extend long cellular processes that wrap around axons multiple times to form this coating. Myelin sheath is required for proper conduction of neuronal signaling and greatly increases the speed at which these messages travel. Microglia—known as the macrop

 Core: Nervous System

Sensory Exam

JoVE 10113

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA


A complete sensory examination consists of testing primary sensory modalities as well as cortical sensory function. Primary sensory modalities include pain, temperature, light touch, vibration,…

 Physical Examinations III

Neurulation

JoVE 10910

Neurulation is the embryological process which forms the precursors of the central nervous system and occurs after gastrulation has established the three primary cell layers of the embryo: ectoderm, mesoderm, and endoderm. In humans, the majority of this system is formed via primary neurulation, in which the central portion of the ectoderm—originally appearing as a flat sheet of cells—folds upwards and inwards, sealing off to form a hollow neural tube. As development proceeds, the anterior portion of the neural tube will give rise to the brain, with the rest forming the spinal cord. The central portion of the ectoderm that bends to generate the neural tube is aptly called the neural ectoderm, while the areas that flank it—along the periphery of the embryo—are the surface ectoderm. However, at the junction of the neural and surface ectoderm lies another population of cells, called the neural crest. As the neural folds (the edges of the elevating neural tube) begin to appear, neural crest cells (NCCs) can be visualized in their tips through the expression of characteristic markers, like the Pax7 transcription factor. As development proceeds and the neural folds fuse, NCCs can be observed either in the top-most portion of the neural tube or migrating along this structure’s sides towards lower regions of the embryo. To migrate, N

 Core: Reproduction and Development

Neural Regulation

JoVE 10835

Digestion begins with a cephalic phase that prepares the digestive system to receive food. When our brain processes visual or olfactory information about food, it triggers impulses in the cranial nerves innervating the salivary glands and stomach to prepare for food.

The cephalic phase is a conditioned or learned response to familiar foods. Our appetite or desire for a particular food modifies the preparatory responses directed by the brain. Individuals may produce more saliva and stomach rumblings in anticipation of apple pie than of broccoli. Appetite and desire are products of the hypothalamus and amygdala—brain areas associated with visceral processes and emotion. After the cephalic phase, digestion is governed by the enteric nervous system (ENS) as an unconditioned reflex. Individuals do not have to learn how to digest food; it happens regardless of whether it is apple pie or broccoli. The ENS is unique in that it functions (mostly) independent of the brain. About 90% of the communication are messages sent from the ENS to the brain rather than the other way around. These messages give the brain information about satiety, nausea, or bloating. The ENS, as part of the peripheral nervous system, is also unique in that it contains both motor and sensory neurons. For example, the ENS directs smooth muscle movements that churn and propel food al

 Core: Nutrition and Digestion

Neuron Structure

JoVE 10842

Neurons are the main type of cell in the nervous system that generate and transmit electrochemical signals. They primarily communicate with each other using neurotransmitters at specific junctions called synapses. Neurons come in many shapes that often relate to their function, but most share three main structures: an axon and dendrites that extend out from a cell body.

The neuronal cell body—the soma— houses the nucleus and organelles vital to cellular function. Extending from the cell body are thin structures that are specialized for receiving and sending signals. Dendrites typically receive signals while the axon passes on the signals to other cells, such as other neurons or muscle cells. The point at which a neuron makes a connection to another cell is called a synapse. Neurons receive inputs primarily at postsynaptic terminals, which are frequently located on spines—small bumps protruding from the dendrites. These specialized structures contain receptors for neurotransmitters and other chemical signals. Dendrites are often highly branched, allowing some neurons to receive tens of thousands of inputs. Neurons most commonly receive signals at their dendrites, but they can also have synapses in other areas, such as the cell body. The signal received at the synapses travels down the dendrite to the soma, where the cell can proce

 Core: Nervous System

Determination

JoVE 10912

During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. Specification is demonstrated by removing a segment of an early embryo, “neutrally” culturing the tissue in vitro—for example, in a petri dish with simple medium—and then observing the derivatives. If the cultured region gives rise to cell types that it would normally generate in the embryo, this means that it is specified. In contrast, determination occurs if a region of the embryo is removed and placed in a “non-neutral” environment—such as in a dish containing complex medium supplemented with a variety of proteins, or even a different area of the embryo itself—and it still generates the expected derivatives. Specification and determination are two sequential steps in the developmental pathway of a cell, which precede the final stage of differentiation, during which mature tissues with unique morphologies and functions are produced. To study specification, researchers must first understand the normal derivatives of different regions of an embryo. To accomplish this, fate maps are often used, which are generated by dyeing or labeling cells early in embryonic development, culturing whole embryos and monitoring where the marked cells end up. For example, such te

 Core: Reproduction and Development

Primary Neuronal Cultures

JoVE 5214

The complexity of the brain often requires neuroscientists to use a simpler system for experimental manipulations and observations. One powerful approach is to generate a primary culture by dissecting nervous system tissue, dissociating it into single cells, and growing those cells in vitro. Primary cultures make neurons and glia easily accessible to the…

 Neuroscience

Chromatin Immunoprecipitation

JoVE 5551

Histones are proteins that help organize DNA in eukaryotic nuclei by serving as “scaffolds” around which DNA can be wrapped, forming a complex called “chromatin”. These proteins can be modified through the addition of chemical groups, and these changes affect gene expression. Researchers use a technique called chromatin immunoprecipitation (ChIP) to …

 Genetics

An Introduction to Aging and Regeneration

JoVE 5337

Tissues are maintained through a balance of cellular aging and regeneration. Aging refers to the gradual loss of cellular function, and regeneration is the repair of damaged tissue generally mediated by preexisting adult or somatic stem cells. Scientists are interested in understanding the biological mechanisms behind these two complex processes. By doing so, researchers may be able to use…

 Developmental Biology

In Vitro Recording of Mesenteric Afferent Nerve Activity in Mouse Jejunal and Colonic Segments

1Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, 2Visceral Pain Group, Discipline of Medicine, University of Adelaide, 3Department of Biomedical Sciences, University of Sheffield, 4Department of Pharmacy, Pharmacology and Postgraduate Medicine, University of Hertfordshire, 5Department of Gastroenterology and Hepatology, Antwerp University Hospital

JoVE 54576

 Neuroscience

Detection of the Genome and Transcripts of a Persistent DNA Virus in Neuronal Tissues by Fluorescent In situ Hybridization Combined with Immunostaining

1Virus and Centromere Team, Centre de Génétique et Physiologie Moléculaire et Cellulaire, CNRS UMR 5534, 2Université de Lyon 1, 3Laboratoire d'excellence, LabEX DEVweCAN, 4Institut de Virologie Moléculaire et Structurale, CNRS UPR 3296, 5Centre de Recherche en Cancérologie de Lyon, INSERM U1052, CNRS UMR 5286

JoVE 51091

 Neuroscience

Structured Motor Rehabilitation After Selective Nerve Transfers

1Clinical Laboratory for Bionic Extremity Reconstruction, Medical University of Vienna, 2Bioengineering Department, Imperial College London, 3Master's Degree Program Health Assisting Engineering, University of Applied Sciences FH Campus Wien, 4Department of Orthopedics and Trauma Surgery, Medical University of Vienna, 5Division of Plastic and Reconstructive Surgery, Department of Surgery, Medical University of Vienna

JoVE 59840

 Medicine

T-maze Forced Alternation and Left-right Discrimination Tasks for Assessing Working and Reference Memory in Mice

1Division of Systems Medical Science, Institute for Comprehensive Medical Science, Fujita Health University, 2Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), 3Center for Genetic Analysis of Behavior, National Institute for Physiological Sciences, National Institutes of Natural Sciences

JoVE 3300

 Neuroscience

High-throughput Analysis of Locomotor Behavior in the Drosophila Island Assay

1Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, 2Centre for Molecular and Biomolecular Informatics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 3Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center

JoVE 55892

 Neuroscience

3D Kinematic Analysis for the Functional Evaluation in the Rat Model of Sciatic Nerve Crush Injury

1Department of Development and Rehabilitation of Motor Function, Human Health Sciences, Graduate School of Medicine, Kyoto University, 2Department of Motor Function Analysis, Human Health Sciences, Graduate School of Medicine, Kyoto University, 3Department of Otolaryngology, The Ohio State University Wexner Medical Center

Video Coming Soon

JoVE 60267

 JoVE In-Press

Use of In Vivo Single-fiber Recording and Intact Dorsal Root Ganglion with Attached Sciatic Nerve to Examine the Mechanism of Conduction Failure

1Department of Neurobiology, School of Basic Medicine, Fourth Military Medical University, 2Department of Toxicology, School of Public Health, ShanXi Medical University, 3Department of Psychology, Fourth Military Medical University, 4Department of Neurobiology, School of Basic Medical Sciences, Advanced Innovation Center for Human Brain Protection, Capital Medical University, 5Neuroscience Research Institute, Key Lab for Neuroscience, Ministry of Education/National Health Commission, Peking University, 6Department of Radiation Biology, Faculty of Preventive Medicine, Fourth Military Medical University

JoVE 59234

 Neuroscience

Targeting Alpha Synuclein Aggregates in Cutaneous Peripheral Nerve Fibers by Free-floating Immunofluorescence Assay

1Laboratory for Biomedical Neurosciences, Neurocenter of Southern Switzerland, 2Neurology Department, Neurocenter of Southern Switzerland, 3Department of Neurology, Inselspital, Bern University Hospital, University of Bern, 4Faculty of Biomedical Sciences, Università della Svizzera Italiana

JoVE 59558

 Neuroscience

Isolation, Propagation, and Prion Protein Expression During Neuronal Differentiation of Human Dental Pulp Stem Cells

1Laboratory of Experimental Medicine and Environmental Pathology, Sabina Universitas - Rieti University Hub, 2Department of Experimental Medicine, Sapienza University of Rome, 3Department of Science Dentistry and Maxillofacial, Sapienza University of Rome

JoVE 59282

 Developmental Biology

A Tripeptide-Stabilized Nanoemulsion of Oleic Acid

1Department of Chemistry, Brooklyn College, The City University of New York, 2Ph.D. Program in Chemistry, The Graduate Center of The City University of New York, 3Ph.D. Program in Biochemistry, The Graduate Center of The City University of New York, 4Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, 5Women's Health Research Institute, Icahn School of Medicine at Mount Sinai, 6Laboratory for Translational Research, Western Connecticut Health Network

JoVE 59034

 Bioengineering

Laboratory Administration of Transcutaneous Auricular Vagus Nerve Stimulation (taVNS): Technique, Targeting, and Considerations

1Department of Biomedical Engineering, City College of New York, 2U.S. Army Research Laboratory, Aberdeen Proving Ground, 3Brain Stimulation Laboratory, Department of Psychiatry, Medical University of South Carolina, 4Department of Pediatrics, Medical University of South Carolina, 5Department of Neurology, Medical University of South Carolina, 6Ralph H. Johnson VA Medical Center

JoVE 58984

 Neuroscience
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