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Sodium Channels: Cell membrane glycoproteins selective for sodium ions. Fast sodium current is associated with the action potential in neural membranes.

Action Potentials

JoVE 10844

Neurons communicate by firing action potentials—the electrochemical signal that is propagated along the axon. The signal results in the release of neurotransmitters at axon terminals, thereby transmitting information in the nervous system. An action potential is a specific “all-or-none” change in membrane potential that results in a rapid spike in voltage.

Neurons typically have a resting membrane potential of about -70 millivolts (mV). When they receive signals—for instance, from neurotransmitters or sensory stimuli—their membrane potential can hyperpolarize (become more negative) or depolarize (become more positive), depending on the nature of the stimulus. If the membrane becomes depolarized to a specific threshold potential, voltage-gated sodium (Na+) channels open in response. Na+ has a higher concentration outside of the cell as compared to the inside, so it rushes in when the channels open, moving down its electrochemical gradient. As positive charge flows in, the membrane potential becomes even more depolarized, in turn opening more channels. As a result, the membrane potential quickly rises to a peak of around +40 mV. At the peak of the action potential, several factors drive the potential back down. The influx of Na+ slows because the Na+ channels start to inactiv

 Core: Nervous System

Gustation

JoVE 10851

Gustation is a chemical sense that, along with olfaction (smell), contributes to our perception of taste. It starts with the activation of receptors by chemical compounds (tastants) dissolved in the saliva. The saliva and filiform papillae on the tongue distribute the tastants and increase their exposure to the taste receptors.

Taste receptors are found on the surface of the tongue as well as on the soft palate, the pharynx, and the upper esophagus. On the tongue, taste receptors are contained within structures called taste buds. The taste buds are embedded within papillae, which are visible on the tongue surface. There are three types of papillae that contain taste buds and their receptors. Circumvallate papillae are the largest papillae and are located near the back of the tongue. Foliate papillae resemble folds on the side of the tongue. Fungiform papillae are found across the front three-quarters of the tongue but are less concentrated in the middle of the tongue. There are five basic tastes: salty, sour, sweet, bitter, and savory (or umami). The perception of salty taste is caused by tastants that release sodium ions upon dissolution. Sour taste, by contrast, is produced by the release of hydrogen ions from dissolved acidic tastants. Salty and sour tastants produce a neural response by depolarizing the membrane directly (salty tastants) or via ion chan

 Core: Sensory Systems

Measurement of Extracellular Ion Fluxes Using the Ion-selective Self-referencing Microelectrode Technique

1Department of Dermatology, Institute for Regenerative Cures, University of California, Davis, 2Departamento de Biologia, Centro de Biologia Molecular e Ambiental, Universidade do Minho, 3Department of Neurology and Center for Neuroscience, University of California, Davis Imaging of Dementia and Aging Laboratory, 4Department of Ophthalmology, Institute for Regenerative Cures, University of California, Davis

JoVE 52782

 Biology

Vibrodissociation of Neurons from Rodent Brain Slices to Study Synaptic Transmission and Image Presynaptic Terminals

1Section on Synaptic Pharmacology/Laboratory for Integrative Neuroscience, National Institutes of Health/National Institute on Alcohol Abuse and Alcoholism, 2Department of Electronics Engineering, Ewha Womans University, 3Section on Transmitter Signaling/Laboratory of Molecular Physiology, National Institutes of Health/National Institute on Alcohol Abuse and Alcoholism

JoVE 2752

 Neuroscience

Primary Culture of Neurons Isolated from Embryonic Mouse Cerebellum

1Department of Human Anatomy and Cell Science, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 2The Children's Hospital Research Institute of Manitoba (CHRIM), Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, 3Department of Oral Biology, University of Illinois at Chicago, 4Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba

Video Coming Soon

JoVE 60168

 JoVE In-Press

Spinal Cord Lateral Hemisection and Asymmetric Behavioral Assessments in Adult Rats

1Department of Spinal Cord Injury and Repair, Trauma and Orthopedics Institute of Chinese PLA, General Hospital of Jinan Military Region, 2Institute of Military Cognitive and Brain Sciences, Academy of Military Medical Sciences, 3Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery and Goodman Campbell Brain and Spine, Indiana University School of Medicine, 4Program in Medical Neuroscience, Paul and Carole Stark Neurosciences Research Institute, Indiana University School of Medicine, 5Shandong University Affiliated Shandong Cancer Hospital and Institute

Video Coming Soon

JoVE 57126

 JoVE In-Press

Plate-based Large-scale Cultivation of Caenorhabditis elegans: Sample Preparation for the Study of Metabolic Alterations in Diabetes

15th Medical Department, Medical Faculty Mannheim, Heidelberg University, 2Department of Internal Medicine, Heidelberg University, 3German Center for Diabetes Research (DZD), 4European Center for Angioscience, Medical Faculty Mannheim, Heidelberg University

JoVE 58117

 Biochemistry

Optogenetic Stimulation of the Auditory Nerve

1InnerEarLab, Department of Otolaryngology, University Medical Center Goettingen, 2Bernstein Focus for Neurotechnology, University of Goettingen, 3Auditory Systems Physiology Group, Department of Otolaryngology, University Medical Center Goettingen, 4Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University of Goettingen, 5Department of Chemical, Electronic, and Biomedical Engineering, University of Guanajuato

JoVE 52069

 Neuroscience

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
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