DOCSLIB.ORG

The Peripheral Nervous System Links the Brain to the “Real” World

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Peripheral Nervous System Organization of Nervous System: Nervous system Integration Central nervous system Peripheral nervous system (CNS) (PNS) Motor Sensory output input Brain Spinal cord Motor division Sensory division (efferent) (afferent) Autonomic nervous system Somatic nervous system (involuntary; smooth & cardiac muscle) (voluntary; skeletal muscle) Sympathetic division Parasympathetic division Peripheral Nervous System The peripheral nervous system links the brain to the “real” world Ganglia (neuron cell bodies) Nerve Types: Nerves 1) Sensory nerves (contains only afferent fibers) (bundles of axons) 2) Motor nerves (contains only efferent fibers) 3) Mixed nerves (contains afferent / efferent fibers) Sensory receptors Most nerves in the human body are mixed nerves Motor output 1 Peripheral Nervous System Nerve Structure: Endoneurium A. Epineurium: • Outside nerve covering • Dense network of collagen fibers Perineurium B. Perineurium: • Divides nerve into fascicles • Contains blood vessels Epineurium C. Endoneurium: • Surrounds individual axons and ties them together Fascicle Marieb & Hoehn – Figure 13.26 Peripheral Nervous System Classification of Nerve Fibers: • Classified according to conduction velocity Relative Relative conduction Classification Type diameter velocity Myelination A alpha (A) Largest Fastest (120 m / s) Yes A beta (A) Medium Medium Yes Sensory and A gamma (A) Medium Medium Yes Motor A delta (A) Small Medium Yes (Erlanger & Gasser) B Small Medium Yes C Smallest Slowest (0.2 m / s) No Ia Largest Fastest Yes Ib Largest Fastest Yes Sensory only II Medium Medium Yes (Lloyd & Hunt) III Small Medium Yes IV Smallest Slowest No 2 Peripheral Nervous System Organization of Nervous System: Nervous system Integration Central nervous system Peripheral nervous system (CNS) (PNS) Motor Sensory output input Brain Spinal cord Motor division Sensory division (efferent) (afferent) Autonomic nervous system Somatic nervous system (involuntary; smooth & cardiac muscle) (voluntary; skeletal muscle) Sympathetic division Parasympathetic division Sensory Systems “Nothing is in the mind that does not pass through the senses” Aristotle (~ 350 B.C.) • Sensory receptors provide the only channels of communication from the external world to the nervous system: • Detections: Electrical impulses - triggered by receptor cells • Sensations: Electrical impulses - reach brain via neurons Subjective • Perceptions: Interpretation of electrical impulses by brain Sensations / perceptions are not inherent in stimuli themselves; instead they depend on the neural processing of the stimuli 3 Sensory Systems Sensory Pathways in NS: Fourth-order midline neuron 1) Receptor: • Converts stimuli to electrochemical energy • Structure variable Cerebral cortex • Specialized epithelial cells (e.g., vision) Third-order neuron • Modified neurons (e.g., olfaction) 2) First-order afferent neuron: • Cell body located in ganglion (PNS) Thalamus Second-order 3) Second-order afferent neuron: neuron • Synapse with first-order neuron at relay nuclei • Many first-order synapse with one second-order Brain stem • Interneurons present (signal processing) • Cross at midline (decussate) 4) Third-order afferent neuron: • Reside in thalamus (relay nuclei) Relay nucleus • Interneurons present (signal processing) Receptor 5) Fourth-order afferent neuron: Spinal • Reside in appropriate sensory area First-order cord neuron Sensory Systems Modality: Category of sensation Sensory Receptors: Type of Receptor: Modality: Location: • Skin (touch) Mechanoreceptors • Inner ear (audition) • Inner ear (vestibular) Touch Audition Vestibular Photoreceptors • Eye (vision) Vision • Tongue (taste) Chemoreceptors • Nose (olfaction) Taste Olfaction Osmolarity • Vessels (osmolarity) Thermoreceptors • Skin (temperature) Temperature Nociceptors • Skin (pain) Pain 4 Guyton & Hall – Figure 46.2 / 46.3 Sensory Systems Sensory Receptors: Sensory transduction: The process by which environmental stimuli activates a receptor and is converted into electrical energy • Receptor excitation = Change in membrane potential (Receptor potential) (usually via opening of ion channels) Example: Pacinian corpuscle 1) Pressure causes a change in the membrane properties (e.g., mechanical deformation) Receptor Potential > Threshold Action Potential 2) Ion channels open; receptor potential develops • Amplitude correlates with stimulus size ( Intensity = Receptor potential = AP frequency) 3) Receptor potential triggers action potential Costanzo – Figure 3.5 / 3.6 Sensory Systems Sensory Receptors: Receptor Field: An area of the body that when stimulated results in a change in firing rate of a sensory neuron Receptor fields may be excitatory or inhibitory Receptor fields exist for first-, Excitatory receptor fields increase firing rate second-, third-, and fourth-order neurons Inhibitory receptor fields decrease firing rate The smaller a receptor field, the more Lateral inhibition defines boundaries precisely the sensation can be localized and provides a contrasting border 5 Sensory Systems Sensory Receptors: Sensory coding: Various aspects of perceived stimuli are encoded and sent to the proper location in the CNS Features encoded: 1) Modality 2) Location 3) Threshold Labeled Line Principle: Threshold of Detection: Receptors respond to Weakest signal that will single modality produce a receptor response 50% of the time Touch Somatosensory Hearing: receptor cortex Vision: Bending of hair equal to 1 photon of light Receptor fields diameter of H atom 4) Intensity 5) Duration • Number of receptors activated Length of time a sensory • Firing rate of sensory neurons neuron fires • Types of receptors activated During prolonged stimulus, receptors “adapt” to the stimulus Sensory Systems Adaptation depends on how quickly receptor potential drops below threshold Sensory Receptors: Sensory adaptation: When a constant stimulus is applied to a receptor, the frequency of action potentials generated declines over time Tonic receptors (slowly adapting receptors) Can encode stimulus intensity Will adapt to extinction; may take hours / days Pattern of adaptation differs among • Transmit impulses as long as different types of receptors stimulus present • Keep brain appraised of body status Guyton & Hall – Figure 46.5 Costanzo – Figure 3.7 6 Sensory Systems Adaptation depends on how quickly receptor potential drops below threshold Sensory Receptors: Sensory adaptation: When a constant stimulus is applied to a receptor, the frequency of action potentials generated declines over time Phasic receptors (rapidly adapting receptors) Can not encode stimulus intensity Pattern of adaptation differs among • Transmit impulses only when different types of receptors change is taking place • Important for predicting future position / condition of body Guyton & Hall – Figure 46.5 Costanzo – Figure 3.7 Costanzo – Figure 3.8 Sensory Systems Rapid adapters = Change in velocity Somatosensory System: Slow adapters = Intensity; duration • Processes information about touch, position, pain, and temperature Mechanoreceptors: Two-point discrimination Pacinian corpuscle Meissner’s corpuscle Location = Subcutaneous; intramuscular Location = Non-hairy skin Detection = Vibration; tapping Detection = Tapping; fluttering Adaptation = Very rapidly Adaptation = Rapidly Hair plexus Ruffini’s corpuscle Location = Hairy skin Location = Skin; joint capsules Detection = Velocity; movement direction Detection = Stretch; joint rotation Adaptation = Rapidly Adaptation = Slowly 7 Costanzo – Figure 3.8 / 3.9 Sensory Systems Rapid adapters = Change in velocity Somatosensory System: Slow adapters = Intensity; duration • Processes information about touch, position, pain, and temperature Mechanoreceptors: Merkel’s receptor / Tactile disc Location = Non-hairy skin / Hairy skin Detection = Vertical indentation Adaptation = Slowly Thermoreceptors: • Slowly adapting receptors; located in skin • Cold receptors vs. warm receptors • Overlap in response ranges • Do not respond at extreme ranges (nociceptors) Sensory Systems Somatosensory System: • Processes information about touch, position, pain, and temperature Nociceptors: • Respond to noxious stimuli that can produce tissue damage Mechanical nociceptors: • Respond to mechanical stimuli • A delta (A) afferent neurons (myelinated) Polymodal nociceptors: • Respond to multiple stimuli: • High-intensity chemical stimuli • Hot / Cold stimuli • C afferent neurons (unmyelinated) Chemical cues released at damaged / Hyperalgesia: Intense activity areas include: Process where axons of nociceptors release • H+ • Prostaglandins substances that sensitize the nociceptors to • K+ • Bradykinins stimuli that were not previously painful • ATP • Substance P 8 Sensory Systems Somatosensory Pathways: midline 1) Dorsal column system • Information transmitted: Cerebral a) Discriminative touch cortex b) Pressure / Vibration c) Two-point discrimination d) Proprioception • Consists mainly of groups I and II fibers Thalamus • Fibers decussate in brain stem (second-order neurons) • Nucleus gracilis = Info from lower body • Nucleus cuneatus = Info from upper body Brain stem Fasciculus Fasciculus cuneatus gracilis Receptor Spinal cord Marieb & Hoehn – Figure 12.33 Sensory Systems Somatosensory Pathways: midline 2) Anterolateral (spinothalamic) system • Information transmitted: Cerebral a) Pain cortex b) Temperature / Light touch • Consists mainly of groups III and IV fibers • Fast pain (e.g., pin prick) • A delta fibers; group II & group III fibers Thalamus
Recommended publications
  • Blue Cone Monochromacy: Visual Function and Efficacy Outcome Measures for Clinical Trials

    Blue Cone Monochromacy: Visual Function and Efficacy Outcome Measures for Clinical Trials

    RESEARCH ARTICLE Blue Cone Monochromacy: Visual Function and Efficacy Outcome Measures for Clinical Trials Xunda Luo1☯‡, Artur V. Cideciyan1☯‡*, Alessandro Iannaccone2, Alejandro J. Roman1, Lauren C. Ditta2, Barbara J. Jennings2, Svetlana A. Yatsenko3, Rebecca Sheplock1, Alexander Sumaroka1, Malgorzata Swider1, Sharon B. Schwartz1, Bernd Wissinger4, Susanne Kohl4, Samuel G. Jacobson1* 1 Scheie Eye Institute, Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America, 2 Hamilton Eye Institute, Department of Ophthalmology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America, 3 Pittsburgh Cytogenetics Laboratory, Center for Medical Genetics and Genomics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America, 4 Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University of Tuebingen, Tuebingen, Germany ☯ These authors contributed equally to this work. ‡ OPEN ACCESS These authors are joint first authors on this work. * [email protected] (SGJ); [email protected] (AVC) Citation: Luo X, Cideciyan AV, Iannaccone A, Roman AJ, Ditta LC, Jennings BJ, et al. (2015) Blue Cone Monochromacy: Visual Function and Efficacy Abstract Outcome Measures for Clinical Trials. PLoS ONE 10(4): e0125700. doi:10.1371/journal.pone.0125700 Academic Editor: Dror Sharon, Hadassah-Hebrew University Medical Center, ISRAEL Background Blue Cone Monochromacy (BCM) is an X-linked retinopathy caused by mutations in the Received: December 29, 2014 OPN1LW / OPN1MW gene cluster, encoding long (L)- and middle (M)-wavelength sensitive Accepted: March 21, 2015 cone opsins. Recent evidence shows sufficient structural integrity of cone photoreceptors in Published: April 24, 2015 BCM to warrant consideration of a gene therapy approach to the disease.
  • Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts After Long-Duration Space Flight

    Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts After Long-Duration Space Flight

    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln NASA Publications National Aeronautics and Space Administration 10-2011 Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts after Long-duration Space Flight Thomas H. Mader Alaska Native Medical Center, [email protected] C. Robert Gibson Coastal Eye Associates Anastas F. Pass University of Houston Larry A. Kramer University of Texas Health Science Center Andrew G. Lee The Methodist Hospital See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/nasapub Part of the Physical Sciences and Mathematics Commons Mader, Thomas H.; Gibson, C. Robert; Pass, Anastas F.; Kramer, Larry A.; Lee, Andrew G.; Fogarty, Jennifer; Tarver, William J.; Dervay, Joseph P.; Hamilton, Douglas R.; Sargsyan, Ashot; Phillips, John L.; Tran, Duc; Lipsky, William; Choi, Jung; Stern, Claudia; Kuyumjian, Raffi; andolk, P James D., "Optic Disc Edema, Globe Flattening, Choroidal Folds, and Hyperopic Shifts Observed in Astronauts after Long-duration Space Flight" (2011). NASA Publications. 69. https://digitalcommons.unl.edu/nasapub/69 This Article is brought to you for free and open access by the National Aeronautics and Space Administration at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in NASA Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Thomas H. Mader, C. Robert Gibson, Anastas F. Pass, Larry A.
  • Photosynthesis

    Photosynthesis

    20 Photosynthesis Plants use sunlight (Photon), (H O) and (CO ) to convert light Energy into chemical Energy by 2 2 chlorophyll. This process is known as photosynthesis. Chemical equation : Sunlight 6CO + 12H O o C H O + 6O + 6H O 2 2 Chlorophyll 6 12 6 2 2 Necessary factors for photoynthesis : Light Chlorophyll Water (H O) 2 Carbon Dioxide (CO ) (0.03 % in the atmosphere) 2 Photosynthetic Organisms : Different types of algae (Blue green algae, Brown algae, Red algae, Green algae). Bryophytes, Pteridophytes, Gymnosperms, Angiosperms. Some bacteria. (Note : Fungi is not able to perform photosynthesis due to lack of chlorophyll.) Advantages of Photosynthesis : Main products of photosynthesis are starch and sucrose. (O ) is byproduct which is used by organisms for respiration. 2 (1) What is produced as byproduct of photosynthesis ? (A) Oxygen (B) Nitrogen (C) Carbon dioxide (D) Sulphur dioxide (2) Which type of energy can be used by all organisms ? (A) Light energy (B) Chemical energy (C) Heat energy (D) Water potential (3) Which of the following type of reaction photosynthesis is ? (A) Anabolic, Endothermic, Reduction (B) Anabolic, Endothermic, Oxidation (C) Catabolic, Exothermic, Oxidation (D) Catabolic, Endothermic, Reduction Answers : (1-A), (2-B), (3-A) 382 History of Photosynthesis : No. Name of Scientist Contribution 1. Joseph Priestly Plants obtain CO from atmosphere and release O . 2 2 (1733-1804) 2. Ingenhouse In bright sunlight, small bubbles were formed around the (1730-1799) green parts of the plant. 3. Julius Von Sachs Green substance (chlorophyll) in plants is located in special (1854) bodies (chloroplast) of plant cell. This green substances produces glucose which is usually stored in the form of starch.
  • The Genetics of Normal and Defective Color Vision

    The Genetics of Normal and Defective Color Vision

    Vision Research xxx (2011) xxx–xxx Contents lists available at ScienceDirect Vision Research journal homepage: www.elsevier.com/locate/visres Review The genetics of normal and defective color vision Jay Neitz ⇑, Maureen Neitz University of Washington, Dept. of Ophthalmology, Seattle, WA 98195, United States article info a b s t r a c t Article history: The contributions of genetics research to the science of normal and defective color vision over the previ- Received 3 July 2010 ous few decades are reviewed emphasizing the developments in the 25 years since the last anniversary Received in revised form 25 November 2010 issue of Vision Research. Understanding of the biology underlying color vision has been vaulted forward Available online xxxx through the application of the tools of molecular genetics. For all their complexity, the biological pro- cesses responsible for color vision are more accessible than for many other neural systems. This is partly Keywords: because of the wealth of genetic variations that affect color perception, both within and across species, Color vision and because components of the color vision system lend themselves to genetic manipulation. Mutations Cone photoreceptor and rearrangements in the genes encoding the long, middle, and short wavelength sensitive cone pig- Colorblindness Cone mosaic ments are responsible for color vision deficiencies and mutations have been identified that affect the Opsin genes number of cone types, the absorption spectra of the pigments, the functionality and viability of the cones, Evolution and the topography of the cone mosaic. The addition of an opsin gene, as occurred in the evolution of pri- Comparative color vision mate color vision, and has been done in experimental animals can produce expanded color vision capac- Cone photopigments ities and this has provided insight into the underlying neural circuitry.
  • Colour Vision Deficiency

    Colour Vision Deficiency

    Eye (2010) 24, 747–755 & 2010 Macmillan Publishers Limited All rights reserved 0950-222X/10 $32.00 www.nature.com/eye Colour vision MP Simunovic REVIEW deficiency Abstract effective "treatment" of colour vision deficiency: whilst it has been suggested that tinted lenses Colour vision deficiency is one of the could offer a means of enabling those with commonest disorders of vision and can be colour vision deficiency to make spectral divided into congenital and acquired forms. discriminations that would normally elude Congenital colour vision deficiency affects as them, clinical trials of such lenses have been many as 8% of males and 0.5% of femalesFthe largely disappointing. Recent developments in difference in prevalence reflects the fact that molecular genetics have enabled us to not only the commonest forms of congenital colour understand more completely the genetic basis of vision deficiency are inherited in an X-linked colour vision deficiency, they have opened the recessive manner. Until relatively recently, our possibility of gene therapy. The application of understanding of the pathophysiological basis gene therapy to animal models of colour vision of colour vision deficiency largely rested on deficiency has shown dramatic results; behavioural data; however, modern molecular furthermore, it has provided interesting insights genetic techniques have helped to elucidate its into the plasticity of the visual system with mechanisms. respect to extracting information about the The current management of congenital spectral composition of the visual scene. colour vision deficiency lies chiefly in appropriate counselling (including career counselling). Although visual aids may Materials and methods be of benefit to those with colour vision deficiency when performing certain tasks, the This article was prepared by performing a evidence suggests that they do not enable primary search of Pubmed for articles on wearers to obtain normal colour ‘colo(u)r vision deficiency’ and ‘colo(u)r discrimination.
  • 1468.Full.Pdf

    1468.Full.Pdf

    1468 • The Journal of Neuroscience, February 11, 2004 • 24(6):1468–1477 Cellular/Molecular Novel Features of Cryptochrome-Mediated Photoreception in the Brain Circadian Clock of Drosophila Andre´ Klarsfeld, Se´bastien Malpel, Christine Michard-Vanhe´e, Marie Picot, Elisabeth Che´lot, and Franc¸ois Rouyer Institut de Neurobiologie Alfred Fessard, Centre National de la Recherche Scientifique, Unite´ Propre de Recherche 2216, 91198 Gif-sur-Yvette, France In Drosophila, light affects circadian behavioral rhythms via at least two distinct mechanisms. One of them relies on the visual photo- transduction cascade. The other involves a presumptive photopigment, cryptochrome (cry), expressed in lateral brain neurons that control behavioral rhythms. We show here that cry is expressed in most, if not all, larval and adult neuronal groups expressing the PERIOD (PER) protein, with the notable exception of larval dorsal neurons (DN2s) in which PER cycles in antiphase to all other known cells. Forcing cry expression in the larval DN2s gave them a normal phase of PER cycling, indicating that their unique antiphase rhythm is related to their lack of cry expression. We were able to directly monitor CRY protein in Drosophila brains in situ. It appeared highly unstable in the light, whereas in the dark, it accumulated in both the nucleus and the cytoplasm, including some neuritic projections. We also show that dorsal PER-expressing brain neurons, the adult DN1s, are the only brain neurons to coexpress the CRY protein and the photoreceptor differentiation factor GLASS. Studies of various visual system mutants and their combination with the cryb mutation indicated that the adult DN1s contribute significantly to the light sensitivity of the clock controlling activity rhythms, and that this contribution depends on CRY.
  • Phototransduction Mediated by Melanopsin in Intrinsically Photosensitive Retinal Ganglion Cells

    Phototransduction Mediated by Melanopsin in Intrinsically Photosensitive Retinal Ganglion Cells

    C.A. Domínguez-Solís, J.A. Pérez-León: Phototransduction mediated by melanopsin Contents available at PubMed www.anmm.org.mx PERMANYER Gac Med Mex. 2015;151:709-20 www.permanyer.com GACETA MÉDICA DE MÉXICO REVIEW ARTICLE Phototransduction mediated by melanopsin in intrinsically photosensitive retinal ganglion cells Carlos Augusto Domínguez-Solís and Jorge Alberto Pérez-León* Department of Chemical-Biological Sciences, Institute of Biomedical Sciences, Universidad Autónoma de Ciudad Juárez, Chihuahua, Chih., México Abstract Melanopsin is the most recent photopigment described. As all the other opsins, it attaches in the retina as chromophore. Its amino acid sequence resembles more invertebrate opsins than those of vertebrates. The signal transduction pathway of opsins in vertebrates is based on the coupling to the G protein transducin, triggering a signaling cascade that results in the hyperpolarization of the plasma membrane. On the contrary, the photoreceptors of invertebrates activate the Gq protein pathway, which leads to depolarizing responses. Phototransduction mediated by melanopsin leads to the depolarization of those cells where it is expressed, the intrinsically photosensitive retinal ganglion cells; the cellular messengers and the ion channel type(s) responsible for the cells´ response is still unclear. Studies to elucidate the signaling cascade of melanopsin in heterologous expression systems, in retina and isolated/cultured intrinsically photosensitive retinal ganglion cells, have provided evidence for the involvement of protein Gq and phospholipase C together with the likely participation of an ion channel member of the transient receptor potential-canonical family, a transduction pathway similar to invertebrate photopigments, particularly Drosophila melanogaster. The intrinsically photosensitive retinal ganglion cells are the sole source of retinal inferences to the suprachiasmatic nucleus; thus, clarifying completely the melanopsin signaling pathway will impact the chronobiology field, including the clinical aspects.
  • 98796-Anatomy of the Orbit

    98796-Anatomy of the Orbit

    Anatomy of the orbit Prof. Pia C Sundgren MD, PhD Department of Diagnostic Radiology, Clinical Sciences, Lund University, Sweden Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lay-out • brief overview of the basic anatomy of the orbit and its structures • the orbit is a complicated structure due to its embryological composition • high number of entities, and diseases due to its composition of ectoderm, surface ectoderm and mesoderm Recommend you to read for more details Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 3 x 3 Imaging technique 3 layers: - neuroectoderm (retina, iris, optic nerve) - surface ectoderm (lens) • CT and / or MR - mesoderm (vascular structures, sclera, choroid) •IOM plane 3 spaces: - pre-septal •thin slices extraconal - post-septal • axial and coronal projections intraconal • CT: soft tissue and bone windows 3 motor nerves: - occulomotor (III) • MR: T1 pre and post, T2, STIR, fat suppression, DWI (?) - trochlear (IV) - abducens (VI) Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Superior orbital fissure • cranial nerves (CN) III, IV, and VI • lacrimal nerve • frontal nerve • nasociliary nerve • orbital branch of middle meningeal artery • recurrent branch of lacrimal artery • superior orbital vein • superior ophthalmic vein Lund University / Faculty of Medicine / Inst. Clinical Sciences / Radiology / ECNR Dubrovnik / Oct 2018 Lund University / Faculty of Medicine / Inst.
  • Intrinsically Photosensitive Retinal Ganglion Cells Gary E

    Intrinsically Photosensitive Retinal Ganglion Cells Gary E

    University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Papers in Veterinary and Biomedical Science Veterinary and Biomedical Sciences, Department of 2011 Intrinsically Photosensitive Retinal Ganglion Cells Gary E. Pickard University of Nebraska-Lincoln, [email protected] Patricia J. Sollars University of Nebraska-Lincoln, [email protected] Follow this and additional works at: http://digitalcommons.unl.edu/vetscipapers Part of the Biochemistry, Biophysics, and Structural Biology Commons, Cell and Developmental Biology Commons, Immunology and Infectious Disease Commons, Medical Sciences Commons, Veterinary Microbiology and Immunobiology Commons, and the Veterinary Pathology and Pathobiology Commons Pickard, Gary E. and Sollars, Patricia J., "Intrinsically Photosensitive Retinal Ganglion Cells" (2011). Papers in Veterinary and Biomedical Science. 268. http://digitalcommons.unl.edu/vetscipapers/268 This Article is brought to you for free and open access by the Veterinary and Biomedical Sciences, Department of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Papers in Veterinary and Biomedical Science by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Published in Review of Physiology, Biochemistry and Pharmacology 162 (2012), pp. 59-90. doi: 10.1007/112_2011_4, Copyright © 2011 Springer-Verlag Berlin Heidelberg. Used by permission. digitalcommons.unl.edu Intrinsically Photosensitive Retinal Ganglion Cells Gary E. Pickard and Patricia J.

  • Eye60. Instrumental Eye Examination.Pdf

    INSTRUMENTAL EYE EXAMINATION Eye60 (1) Instrumental Eye Examination Last updated: May 9, 2019 “BEDSIDE” EXAMINATIONS ..................................................................................................................... 1 OPHTHALMOSCOPY (FUNDUSCOPY) ........................................................................................................ 1 DIRECT OPHTHALMOSCOPY .................................................................................................................... 1 INDIRECT OPHTHALMOSCOPY ................................................................................................................. 2 OPHTHALMOSCOPIC FINDINGS ............................................................................................................... 2 Hypertensive retinopathy ................................................................................................................. 6 Diabetic retinopathy ......................................................................................................................... 7 PEDIATRIC ASPECTS ............................................................................................................................... 9 APPLANATION TONOMETRY .................................................................................................................... 9 SLIT LAMP EXAMINATION (BIOMICROSCOPY) ........................................................................................ 9 ULTRASONOGRAPHY ..............................................................................................................................
  • Anatomy and Physiology of the Afferent Visual System

    Anatomy and Physiology of the Afferent Visual System

    Handbook of Clinical Neurology, Vol. 102 (3rd series) Neuro-ophthalmology C. Kennard and R.J. Leigh, Editors # 2011 Elsevier B.V. All rights reserved Chapter 1 Anatomy and physiology of the afferent visual system SASHANK PRASAD 1* AND STEVEN L. GALETTA 2 1Division of Neuro-ophthalmology, Department of Neurology, Brigham and Womens Hospital, Harvard Medical School, Boston, MA, USA 2Neuro-ophthalmology Division, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA INTRODUCTION light without distortion (Maurice, 1970). The tear–air interface and cornea contribute more to the focusing Visual processing poses an enormous computational of light than the lens does; unlike the lens, however, the challenge for the brain, which has evolved highly focusing power of the cornea is fixed. The ciliary mus- organized and efficient neural systems to meet these cles dynamically adjust the shape of the lens in order demands. In primates, approximately 55% of the cortex to focus light optimally from varying distances upon is specialized for visual processing (compared to 3% for the retina (accommodation). The total amount of light auditory processing and 11% for somatosensory pro- reaching the retina is controlled by regulation of the cessing) (Felleman and Van Essen, 1991). Over the past pupil aperture. Ultimately, the visual image becomes several decades there has been an explosion in scientific projected upside-down and backwards on to the retina understanding of these complex pathways and net- (Fishman, 1973). works. Detailed knowledge of the anatomy of the visual The majority of the blood supply to structures of the system, in combination with skilled examination, allows eye arrives via the ophthalmic artery, which is the first precise localization of neuropathological processes.
  • Using the Ophthalmoscope: Viewing the Optic Disc and Retina

    Using the Ophthalmoscope: Viewing the Optic Disc and Retina

    Using the Ophthalmoscope: Viewing the Optic Disc and Retina Judith Warner, MD University of Utah THE OPHTHALMOSCOPE DIRECT OPHTHALMOSCOPY • Jan Purkinje 1823 • Hermann von Helmholtz 1851 • Hand held ophthalmoscope • Direct up-right image Dials of the Ophthalmoscope RED-FREE FILTER (GREEN LIGHT) 450 nm monochromatic light nerve fiber layer optic nerve drusen OTHER DIALS • Used for measuring lesion size • Looking for the center of fixation OTHER DIALS: SLIT BEAM The wheel has lenses of power Panoptic-ophthalmoscope Direct type Wider field of view Distance from pt greater Similar apertures Not as easy to carry Slightly dimmer light source Not as magnified view of Disc Clean the rubber cup between patients Photographs: http://panoptic.welchallyn.com/faq.html WHEN EVER POSSIBLE: DILATE THE PATIENT Steps to Direct Ophthalmoscopy • Dimly lit room • Dilating drops • Patient fixates distant target • Align yourself • Red reflex • Dial in HOW TO USE THE DIRECT Ophthalmoscope.avi ophthalmoscope.wmv THE RED REFLEX The layers you will go through to see the optic disc THE OPTIC NERVE WHAT YOU SHOULD OBSERVE IN EVERYONE RIGHT EYE AND LEFT EYE THE NORMAL DISC • The disc is 1.62 mm or 1 million fibers • Central retinal artery and vein • Lamina Cribrosa • The optic cup The Normal Disc Appearance The lamina cribrosa is an important disc structure --Means Sieve --Anatomically present in all discs --Visible in about 1/3 --Shallow in myopia Look at the Cup-to-disc ratio: WHAT IS THE CUP-TO-DISC RATIO? .7 NO CUP 0.1 CUP 0.3 CUP 0.7 CUP 0.9 CUP What is the cup