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Brain Stem: The part of the brain that connects the cerebral hemispheres with the spinal cord. It consists of the Mesencephalon; Pons; and Medulla oblongata.

Motor Units

JoVE 10871

A motor unit consists of two main components: a single efferent motor neuron (i.e., a neuron that carries impulses away from the central nervous system) and all of the muscle fibers it innervates. The motor neuron may innervate multiple muscle fibers, which are single cells, but only one motor neuron innervates a single muscle fiber.

Lower motor neurons are efferent neurons that control skeletal muscle, the most abundant type of muscle in the body. The cell bodies of lower motor neurons are located in the spinal cord or brain stem. Those in the brainstem transmit nerve signals through the cranial nerve, and primarily control muscles in the head and neck. Lower motor neurons originating in the spinal cord send signals along the spinal nerve, and primarily control muscles in the limbs and body trunk. A lower motor neuron fires an action potential that, at once, contract all skeletal muscle cells that the neuron innervates. Thus, motor units are functional units of skeletal muscle. The size of a motor unit, or the number of muscle fibers the lower motor neuron innervates, varies depending on the size of the muscle and the speed and precision the movement requires. Muscles in the eyes and fingers, which require rapid, precise control, are generally controlled by small motor units. In these units, motor neurons connect to a small number of muscle f

 Core: Musculoskeletal 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 Spinal Cord

JoVE 10872

The spinal cord is the body’s major nerve tract of the central nervous system, communicating afferent sensory information from the periphery to the brain and efferent motor information from the brain to the body. The human spinal cord extends from the hole at the base of the skull, or foramen magnum, to the level of the first or second lumbar vertebra.

The spinal cord is cylindrical and contains both white and grey matter. In the center is the central canal, which is the remnant of the lumen of the primitive neural tube and is part of the internal system of cerebrospinal fluid cavities. In cross-section, the grey matter surrounding the central canal appears butterfly-shaped. The wings of the butterfly are divided into dorsal and ventral horns. The dorsal horn contains sensory nuclei that relay sensory information, and the ventral horn contains motor neurons that give rise to the axons that innervate skeletal muscle. White matter surrounds the gray matter and contains large numbers of myelinated fibers. The white matter is arranged into longitudinal bundles called dorsal, lateral, and ventral columns. Three membranes surround the spinal cord: the pia adheres closely to the surface of the spinal cord, followed by the arachnoid, and the dura mater—the tough outermost sheath. The spinal cord is divided into four different r

 Core: Musculoskeletal System

The Vestibular System

JoVE 10856

The vestibular system is a set of inner ear structures that provide a sense of balance and spatial orientation. This system is comprised of structures within the labyrinth of the inner ear, including the cochlea and two otolith organs—the utricle and saccule. The labyrinth also contains three semicircular canals—superior, posterior, and horizontal—that are oriented on different planes. All of these structures contain vestibular hair cells—the sensory receptors of the vestibular system. In the otolith organs, the hair cells sit beneath a gelatinous layer called the otolithic membrane, which contains otoconia—calcium carbonate crystals—making it relatively heavy. When the head is tilted, the otolithic membrane shifts, bending the stereocilia on the hair cells. In the semicircular canals, the cilia of the hair cells are contained within a gelatinous cupula, which is surrounded by endolymph fluid. When the head experiences movements, such as rotational acceleration and deceleration, the fluid moves, bending the cupula and the cilia within it. Similar to the auditory hair cells, displacement towards the tallest cilium causes mechanically-gated ion channels to open, depolarizing the cell and increasing neurotransmitter release. Displacement towards the shortest cilium hyperpolarizes the cell and decreases neurotr

 Core: Sensory Systems

Somatosensation

JoVE 10859

The somatosensory system relays sensory information from the skin, mucous membranes, limbs, and joints. Somatosensation is more familiarly known as the sense of touch. A typical somatosensory pathway includes three types of long neurons: primary, secondary, and tertiary. Primary neurons have cell bodies located near the spinal cord in groups of neurons called dorsal root ganglia. The sensory neurons of ganglia innervate designated areas of skin called dermatomes. In the skin, specialized structures called mechanoreceptors transduce mechanical pressure or distortion into neural signals. In hairless skin, most disturbances can be detected by one of four types of mechanoreceptors. Two of these, Merkel disks and Ruffini endings, are slow-adapting and continue to respond to stimuli that remain in prolonged contact with the skin. Merkel disks respond to light touch. Ruffini endings detect deeper static touch, skin stretch, joint deformation, and warmth. The other two major cutaneous mechanoreceptors, Meissner corpuscles and Pacinian corpuscles, are rapidly-adapting. These mechanoreceptors detect dynamic stimuli, like those required to read Braille. Meissner corpuscles are responsive to delicate touch and pressure, as well as low-frequency vibrations. Pacinian corpuscles respond best to deep, repetitive pressure and high-frequency vibrations. Information detected

 Core: Sensory Systems

Sterile Tissue Harvest

JoVE 10298

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN


In 1959 The 3 R's were introduced by W.M.S. Russell and R.L. Burch in their book The Principles of Humane Experimental Technique. The 3 R's are replacement, reduction, and refinement of the use of animals in research.1 The …

 Lab Animal Research

Nociception

JoVE 10873

Nociception—the ability to feel pain—is essential for an organism’s survival and overall well-being. Noxious stimuli such as piercing pain from a sharp object, heat from an open flame, or contact with corrosive chemicals are first detected by sensory receptors, called nociceptors, located on nerve endings. Nociceptors express ion channels that convert noxious stimuli into electrical signals. When these signals reach the brain via sensory neurons, they are perceived as pain. Thus, pain helps the organism avoid noxious stimuli. The immune system plays an essential role in pain pathology. Upon encountering noxious stimuli, immune cells such as mast cells and macrophages present at the site of injury release inflammatory chemicals such as cytokines, chemokines, histamines, and prostaglandins. These chemicals attract other immune cells such as monocytes and T cells to the injury site. They also stimulate nociceptors, resulting in hyperalgesia—a more intense response to a previously painful stimulus, or allodynia—a painful response to a normally innocuous stimulus such as light touch. Such pain sensitization helps protect the injured site during healing. In some cases, pain outlives its role as an acute warning system if sensitization fails to resolve over time. Chronic pain—persistent or recurrent pain lasting longer than t

 Core: Musculoskeletal System

Modified Roller Tube Method for Precisely Localized and Repetitive Intermittent Imaging During Long-term Culture of Brain Slices in an Enclosed System

1Department of Biochemistry and Molecular Biology and Molecular, Cellular and Integrated Neuroscience Program, Colorado State University, 2IBMC-Instituto de Biologia Molecular e Celular, i3S-Instituto de Investigaçãoe Inovação em Saúde, ICBAS, Universidade do Porto, 3Denali Therapeutics

JoVE 56436

 Neuroscience

An Enzyme- and Serum-free Neural Stem Cell Culture Model for EMT Investigation Suited for Drug Discovery

1Dept. of Biomedicine, Pharmacenter, University of Basel, 2Molecular Signalling and Gene Therapy, Narayana Nethralaya Foundation, Narayana Health City, 3Brain Ischemia and Regeneration, Department of Biomedicine, University Hospital Basel, 4Department of Neurosurgery, Klinikum Idar-Oberstein, 5Department of Neurosurgery and Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, 6Department of Neurology, Laboratory of Molecular Neuro Oncology, University Hospital of Zurich

JoVE 54018

 Developmental Biology

Lesion Explorer: A Video-guided, Standardized Protocol for Accurate and Reliable MRI-derived Volumetrics in Alzheimer's Disease and Normal Elderly

1LC Campbell Cognitive Neurology Research Unit, Heart & Stroke Foundation Canadian Partnership for Stroke Recovery, Brain Sciences Research Program, Sunnybrook Health Sciences Centre, 2Department of Medicine (Neurology), Institute of Medical Science, University of Toronto

JoVE 50887

 Medicine

Antibody Binding Specificity for Kappa (Vκ) Light Chain-containing Human (IgM) Antibodies: Polysialic Acid (PSA) Attached to NCAM as a Case Study

1Department of Neurology, Mayo Clinic, 2Mayo Clinic Center for Multiple Sclerosis and Autoimmune Neurology, Mayo Clinic, 3Center for Regenerative Medicine, Neuroregeneration, Mayo Clinic, 4Division of Neonatal Medicine, Mayo Clinic, 5Department of Pediatric and Adolescent Medicine, Mayo Clinic

JoVE 54139

 Immunology and Infection

Improved 3D Hydrogel Cultures of Primary Glial Cells for In Vitro Modelling of Neuroinflammation

1Department of Psychiatry, University of Alberta, 2Alberta Innovates-Health Solutions Interdisciplinary Team in Smart Neural Prostheses (Project SMART), University of Alberta, 3Department of Chemical and Materials Engineering, University of Alberta, 4Division of Physical Medicine and Rehabilitation, University of Alberta, 5Centre for Neuroscience, University of Alberta

JoVE 56615

 Bioengineering

Data Acquisition and Analysis In Brainstem Evoked Response Audiometry In Mice

1Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices, 2KBRwyle GmbH, 3Cognitive Neurophysiology, Department of Psychiatry and Psychotherapy, Faculty of Medicine, University of Cologne, 4Molecular and Cellular Cognition, German Center for Neurodegenerative Diseases (DZNE), 5Institute of Neurophysiology, Faculty of Medicine, University of Cologne, 6Federal Institute for Drugs and Medical Devices (BfArM), 7Thescon GmbH

JoVE 59200

 Neuroscience

Stereological Estimation of Cholinergic Fiber Length in the Nucleus Basalis of Meynert of the Mouse Brain

1Laboratory for Alzheimer's Disease and Aging Research, Kansas City Veterans Affairs Medical Center, 2Department of Neurology, University of Kansas Medical Center, 3Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 4The University of Kansas Alzheimer's Disease Center

Video Coming Soon

JoVE 60405

 JoVE In-Press

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

Assessing Cellular Stress and Inflammation in Discrete Oxytocin-secreting Brain Nuclei in the Neonatal Rat Before and After First Colostrum Feeding

1Department of Psychiatry, Columbia University, 2Department of Pathology & Cell Biology, Columbia University Medical Center, 3Department of Psychiatry, Division of Molecular Imaging and Neuropathology, New York State Psychiatric Institute, 4EB Sciences

JoVE 58341

 Immunology and Infection

Cannula Implantation into the Cisterna Magna of Rodents

1Center for Translational Neuromedicine, Division of Glial Therapeutics, University of Copenhagen, 2Department of Anesthesiology, Yale School of Medicine, 3Center for Translational Neuromedicine, Division of Glial Therapeutics, University of Rochester Medical Center, 4Department of Experimental Medical Science, Wallenberg Center for Molecular Medicine, Lund University

JoVE 57378

 Neuroscience

In Vivo Morphometric Analysis of Human Cranial Nerves Using Magnetic Resonance Imaging in Menière's Disease Ears and Normal Hearing Ears

1Department of Radiology, University Hospital, LMU Munich, 2Department of Otorhinolaryngology - Head and Neck Surgery, SLK-Kliniken Heilbronn GmbH, 3Department of Otorhinolaryngology Head and Neck Surgery, Ludwig-Maximilians-University Hospital Munich, German Centre for Vertigo and Balance Disorder

JoVE 57091

 Medicine
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