DOCSLIB.ORG

The Senses Reception of a Stimulus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

The Senses eg. individual sensitivities, eg colorblindness we spend our lives in an ocean of sensory stimuli: ! unusual pathways, eg synesthesia light gravity electrical currents vibrations time our survival depends on our ability to perceive, interpret and respond to these signals Reception vs Perception Reception is the mechanism and structures involved in detecting and transmitting sensory information our body has millions of sensory receptors All sensory receptors are “connected to” our CNS by way of sensory neurons these neurons travel through the Cranial or Spinal nerves to the brain or spinal cord Perception is the conscious awareness of sensory stimuli is a higher level process of integration and interpretation depends on how the brain processes the signals it is receiving Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 1 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 2 photoreceptor - light Reception of a Stimulus chemoreceptor - chemicals mechanoreceptor - bending, pressure, touch Reception of a sensation is determined by: thermoreceptor - temperature osmoreceptor – salt/water conc 1. Source of Sensory Stimuli baroreceptor - fluid pressure each sensory receptor is designed to transduce we can classify receptors by their location or only one kind of stimulus regardless of the source of the stimulus they respond to: how it is stimulated a. exteroceptors eg hard hit on head ! “see stars” near surface of body eg. spicy food monitor external environment eg. menthol cough drop most special senses 3. Density of Receptors & Size of Receptive b. visceroceptors (interoceptors) Field deep monitor internal environment 99% of receptors in body not evenly distributed over surface of body c. proprioceptors most tip of tongue (specialized kind of visceroceptor) lips monitors relationship of external to internal fingertips environment nose position and movement back of hand orientation wrt gravity least back of neck 2. Kind of Transducer (Modality) braille exploits high tactile acuity of fingertips 4. Intensity of stimulus sensory receptors are transducers ! receptors convert one form of energy into another increase in stimulus intensity that the brain can interpret ! increased frequency of firing sensory receptors are designed to respond best to a single kind of stimulus: if over stimulated – become pain receptors Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 3 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 4 5. Duration of Stimulus eg. pain receptors, some touch, heat, cold, pressure, smell tonic receptors = the sensory neuron fires as long as it is being stimulated B. Encapsulated Receptors (=corpuscular receptors) eg. taste, pain, body position, chemicals in blood a simple receptor encapsulated in layers of connective tissue phasic receptors = continuous stimulation of receptors eventually results in loss of eg. Meissners Corpuscles egg shaped response just beneath skin in dermal papillae especially lips and finger tips !sensory adaptation exteroceptors mechanoreceptors – light pressure important in detecting changes in eg. Pacinian Corpuscles stimuli, not duration of the deep subcutaneous tissues and viscera same stimulus deep pressure and vibrations largest simple receptor cells (2mm, naked eye) mechanoreceptors eg. smell, touch, temperature 6. Structure of Sensory Receptor receptors for special senses are more complex C. Receptor Cells that synapses with Sensations can be produced by very simple sensory neuron kinds of receptors or complex sense organs eg. taste receptors receptors for General Senses are relatively simple D. Complex Sense Organs Receptor Cells are part of more complex sense A. Free Nerve Endings organ Direct stimulation of sensory neurons components of rather elaborate sense organs eg. eye, ear, etc the sensory neuron is also the receptor ! dendrites of sensory neurons Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 5 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 6 Cutaneous Sensations 5. Temperature free nerve endings (=”Touch”) heat and cold are separate receptors the skin possesses ~200,000 thermoreceptors “touch” is a combination of perceptions from a variety 6. Pain of simple receptors nocioceptors in almost every tissue of body located in skin, connective tissue and all receptor types, if overstimulated, become pain receptors mucous membranes may be free nerve endings or enclosed in capsule of epithelial tissue or connective tissue !~64 million receptors in skin they deliver more kinds of information than any single receptor of the special senses Elements of Sense of Touch 1. Touch Meisner’s corpuscles esp fingertips, palms, soles, tongue, lips, nipples, penis 2. Pressure Pacinian corpuscles 3. Vibration Pacinian corpuscles 4. Itch and Tickle free nerve endings Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 7 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 8 The Nose & since they are neurons, they are replaced only very The Physiology of Smell slowly and not as quickly as they are lost both our senses of taste and smell are based mainly on ! some replacement chemoreceptors ! but overall, we loose ~1%/yr ! loose sense of smell as we get older smell ! detects airborne chemicals that enter nasal olfactory receptors are extremely sensitive cavity we are able to detect >10,000 different chemicals a chemical can be smelled only if it is volatile (most: 2000 – 4000) (=ie. able to become airborne) mostly small molecules we have ~350 distinct kinds of receptor proteins long range ! seem to be grouped into 15 – 30 “families” of odors receptors are located in roof and walls of nasal some can detect a single molecule of certain chemicals passages eg. can smell mercaptans (skunks) 1pt in 30 Billion 10-20 Million olfactory neurons in olfactory mucosa in an area about the size of a postage stamp women are more sensitive to smells than are men receptors are free nerve endings though very sensitive, they adapt quickly !dendrites of bipolar neurons olfactory signals can reach the cerebral cortex neurons pass through cribiform plate and connect to (temporal lobe) before they pass through the olfactory bulb on anterior ventral surface of brain thalamus olfactory neurons are the only neurons in the body some applications of olfactory physiology: directly exposed to external environment eg. Morning Sickness ! life span of only ~60 days Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 9 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 10 during pregnancy sense of smell becomes much more acute due to action of estrogen which increases during pregnancy Taste Buds & ! may lead to morning sickness The Physiology of Taste almost all stimuli for nausea are odors also due to chemoreceptors: esp smell of cooking foods, esp meats and bacon ! detects certain chemicals in foods and drink sometimes also coffee, perfumes, cigarette smoke, petroleum products, etc must be water soluble eg. Military use of smell for crowd control eg. starch powder in insoluble ! has no taste short range; requires direct contact with “food” taste receptors are much less sensitive than smell receptors taste receptors located in tastebuds !4000 - 10,000 taste buds !most on tongue ! on papillae each papilla contains up to 200 taste buds some on soft palate and in throat, cheeks each taste bud is a cluster of 50-150 spindle shaped taste cells taste cells synapse with sensory neurons taste cells are replaced every 7-10 days Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 11 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 12 !continually replaced throughout life also, many flavors depend on smell each taste bud acts as a chemoreceptor ! taste is up to 80% smell ! presence of specific chemical initiates nerve hold nose to take medicine impulse older people complain of lost taste but actually are losing smell ! most taste buds respond to 2-4 taste modalities interaction of all these kinds of receptors produces Flavors detected by taste receptors: all the flavors of food and drink sweet - respond to sugars, some amino acids sour - respond to acids bitter - respond to alkaloids (eg. quinine, nicotine, caffeine) salty - respond to inorganic salts and metal ions umami - (=’delicious, savory’) respond to meaty flavor, glutamate, aspartate, MSG all primary taste sensations are detected in all areas of the tongue in spite of “taste maps” of the tongue: tonic receptors ! don’t adapt quickly the sense of taste also involves additional receptor types: thermoreceptors (spicy hot, menthol) mechanoreceptors (texture) nocioceptors (spicy) Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 13 Human Anatomy & Physiology: The Senses; Ziser, Lecture Notes 2010.3 14 The Eye & The Physiology of Vision contains numerous blood vessels highly pigmented eye might be considered our most important sense organ anteriorly is modified into 2 sphincter muscles: of all the nerve fibers making up the 12 pairs of cranial iris – smooth muscle in doughnut shape nerves: pupil – opening in center of iris 38% of them are contained in the optic nerve ciliary body – ring of muscle behind iris we usually use data from our other senses only to supplement visual information lens – held in place by ciliary body Structure flattened, tightly compressed cells=lens fibers the eyeball is spherical 3. retina consists of 3 layers: innermost coat of eyeball
Recommended publications
  • On the Existence of Mechanoreceptors Within the Neurovascular Unit of the Rodent and Rabbit Brain

    On the Existence of Mechanoreceptors Within the Neurovascular Unit of the Rodent and Rabbit Brain

    bioRxiv preprint doi: https://doi.org/10.1101/480921; this version posted November 28, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. On the existence of mechanoreceptors within the neurovascular unit of the rodent and rabbit brain Jorge Larriva-Sahd, Martha León-Olea (*), Víctor Vargas-Barroso (**), Alfredo Varela-Echavarría and Luis Concha Departments of Developmental Biology and Physiology, Instituto de Neurobiología. Campus Juriquilla. Universidad Nacional Autónoma de México. Boulevard Universitario 3001, Juriquilla, Querétaro, CP 76230, México. (*) Department of Functional Neuromorphology, Instituto Mexicano de Psiquiatría “Ramón de la Fuente Muñiz” Av México Xochimilco 101, Delegación Tlalpan CP14370, México DF, México. (**) Present address: Institute of Science and Technology Austria (IST), Am Campus 1, 3400, Klosterneuburg, Austria.Correspondence: Correspondence: Jorge Larriva-Sahd e-mail: [email protected] Telephone: 5256-234030 Orcid ID: 0000-0002-7254-0773 bioRxiv preprint doi: https://doi.org/10.1101/480921; this version posted November 28, 2018. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. Abstract. We describe a set of perivascular interneurons (PINs) originating a series of fibro-vesicular complexes (FVCs) throughout the gray matter of the adult rabbit and rat brain. PINs-FVCs are ubiquitous throughout the brain vasculature as defined in Golgi-impregnated specimens.
  • Chemoreception

    Chemoreception

    Senses 5 SENSES live version • discussion • edit lesson • comment • report an error enses are the physiological methods of perception. The senses and their operation, classification, Sand theory are overlapping topics studied by a variety of fields. Sense is a faculty by which outside stimuli are perceived. We experience reality through our senses. A sense is a faculty by which outside stimuli are perceived. Many neurologists disagree about how many senses there actually are due to a broad interpretation of the definition of a sense. Our senses are split into two different groups. Our Exteroceptors detect stimulation from the outsides of our body. For example smell,taste,and equilibrium. The Interoceptors receive stimulation from the inside of our bodies. For instance, blood pressure dropping, changes in the gluclose and Ph levels. Children are generally taught that there are five senses (sight, hearing, touch, smell, taste). However, it is generally agreed that there are at least seven different senses in humans, and a minimum of two more observed in other organisms. Sense can also differ from one person to the next. Take taste for an example, what may taste great to me will taste awful to someone else. This all has to do with how our brains interpret the stimuli that is given. Chemoreception The senses of Gustation (taste) and Olfaction (smell) fall under the category of Chemoreception. Specialized cells act as receptors for certain chemical compounds. As these compounds react with the receptors, an impulse is sent to the brain and is registered as a certain taste or smell. Gustation and Olfaction are chemical senses because the receptors they contain are sensitive to the molecules in the food we eat, along with the air we breath.
  • Understanding Sensory Processing: Looking at Children's Behavior Through the Lens of Sensory Processing

    Understanding Sensory Processing: Looking at Children's Behavior Through the Lens of Sensory Processing

    Understanding Sensory Processing: Looking at Children’s Behavior Through the Lens of Sensory Processing Communities of Practice in Autism September 24, 2009 Charlottesville, VA Dianne Koontz Lowman, Ed.D. Early Childhood Coordinator Region 5 T/TAC James Madison University MSC 9002 Harrisonburg, VA 22807 [email protected] ______________________________________________________________________________ Dianne Koontz Lowman/[email protected]/2008 Page 1 Looking at Children’s Behavior Through the Lens of Sensory Processing Do you know a child like this? Travis is constantly moving, pushing, or chewing on things. The collar of his shirt and coat are always wet from chewing. When talking to people, he tends to push up against you. Or do you know another child? Sierra does not like to be hugged or kissed by anyone. She gets upset with other children bump up against her. She doesn’t like socks with a heel or toe seam or any tags on clothes. Why is Travis always chewing? Why doesn’t Sierra liked to be touched? Why do children react differently to things around them? These children have different ways of reacting to the things around them, to sensations. Over the years, different terms (such as sensory integration) have been used to describe how children deal with the information they receive through their senses. Currently, the term being used to describe children who have difficulty dealing with input from their senses is sensory processing disorder. _____________________________________________________________________ Sensory Processing Disorder
  • The Roles and Functions of Cutaneous Mechanoreceptors Kenneth O Johnson

    The Roles and Functions of Cutaneous Mechanoreceptors Kenneth O Johnson

    455 The roles and functions of cutaneous mechanoreceptors Kenneth O Johnson Combined psychophysical and neurophysiological research has nerve ending that is sensitive to deformation in the resulted in a relatively complete picture of the neural mechanisms nanometer range. The layers function as a series of of tactile perception. The results support the idea that each of the mechanical filters to protect the extremely sensitive recep- four mechanoreceptive afferent systems innervating the hand tor from the very large, low-frequency stresses and strains serves a distinctly different perceptual function, and that tactile of ordinary manual labor. The Ruffini corpuscle, which is perception can be understood as the sum of these functions. located in the connective tissue of the dermis, is a rela- Furthermore, the receptors in each of those systems seem to be tively large spindle shaped structure tied into the local specialized for their assigned perceptual function. collagen matrix. It is, in this way, similar to the Golgi ten- don organ in muscle. Its association with connective tissue Addresses makes it selectively sensitive to skin stretch. Each of these Zanvyl Krieger Mind/Brain Institute, 338 Krieger Hall, receptor types and its role in perception is discussed below. The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218-2689, USA; e-mail: [email protected] During three decades of neurophysiological and combined Current Opinion in Neurobiology 2001, 11:455–461 psychophysical and neurophysiological studies, evidence has accumulated that links each of these afferent types to 0959-4388/01/$ — see front matter © 2001 Elsevier Science Ltd. All rights reserved. a distinctly different perceptual function and, furthermore, that shows that the receptors innervated by these afferents Abbreviations are specialized for their assigned functions.
  • What Is Sensory Defensiveness? by Ann Stensaas, M.S., OTR/L

    What Is Sensory Defensiveness? by Ann Stensaas, M.S., OTR/L

    Super Duper® Handy Handouts!® Number 174 What Is Sensory Defensiveness? by Ann Stensaas, M.S., OTR/L Does your child get upset by tags in clothing, the sound of the vacuum cleaner, or certain smells in the environment? If so, your child may be showing signs of sensory defensiveness. Sensory defensiveness is a negative reaction to one or more types of sensations (such as touch, movement, sound, taste/texture, or smell), often requiring you to control his/her daily routine to avoid such things. Types of Sensory Defensiveness There are different types of sensory defensiveness including tactile (touch), gravitational (movement and balance), auditory (hearing), and oral defensiveness (taste, smell, texture). Tactile Defensiveness (Touch) The tactile system is our sense of touch. It protects us from danger and helps us identify different objects in the environment. A child showing signs of tactile defensiveness may: Overreact to ordinary touch experiences (e.g., touching play dough or being touched by someone). Avoid daily activities (e.g., washing face/hands or brushing hair). Avoid light touch (e.g., a kiss) but seek out deep touch (e.g., a bear hug). Vestibular Insecurity (Balance/Movement) The vestibular system is our sense of movement and balance. It tells us where our head and body are in relation to gravity and other objects and supports our vision, posture, emotions, and coordination skills. A child showing signs of gravitational insecurity may: Have an excessive fear of falling during ordinary movement activities (e.g., swinging, riding a bicycle, or climbing). Become overwhelmed by changes in head position (e.g., being upside down).
  • Levitis Et Al 2009

    Levitis Et Al 2009

    Animal Behaviour 78 (2009) 103–110 Contents lists available at ScienceDirect Animal Behaviour journal homepage: www.elsevier.com/locate/yanbe Behavioural biologists do not agree on what constitutes behaviour Daniel A. Levitis*, William Z. Lidicker, Jr, Glenn Freund Museum of Vertebrate Zoology and Department of Integrative Biology, University of California, Berkeley article info Behavioural biology is a major discipline within biology, centred on the key concept of ‘behaviour’. But Article history: how is ‘behaviour’ defined, and how should it be defined? We outline what characteristics we believe Received 10 February 2009 a scientific definition should have, and why we think it is important that a definition have these traits. Initial acceptance 12 March 2009 We then examine the range of available published definitions for behaviour. Finding no consensus, we Final acceptance 23 March 2009 present survey responses from 174 members of three behaviour-focused scientific societies as to their Published online 3 June 2009 understanding of the term. Here again, we find surprisingly widespread disagreement as to what MS. number: AE-09-00083 qualifies as behaviour. Respondents contradict themselves, each other and published definitions, indi- cating that they are using individually variable intuitive, rather than codified, meanings of ‘behaviour’. Keywords: We offer a new definition, based largely on survey responses: behaviour is the internally coordinated behaviour responses (actions or inactions) of whole living organisms (individuals or groups) to internal and/or definition external stimuli, excluding responses more easily understood as developmental changes. Finally, we level of organization philosophy of science discuss the usage, meanings and limitations of this definition. Ó 2009 The Association for the Study of Animal Behaviour.
  • Parallel Processing of Cutaneous Information in the Somatosensory System of the Cat

    Parallel Processing of Cutaneous Information in the Somatosensory System of the Cat

    LE JOURNAL CANADIEN DES SCIENCES NEUROLOGIQUES Parallel Processing of Cutaneous Information in the Somatosensory System of the Cat ROBERT W. DYKES RESUME: Dans le passe le principe de In the past, studies of the somatosen­ beginning (Adrian, 1941) although it base des mecanismes corticaux du systeme sory system have played a major role was not reported in man until much sensitif furent fondes en grande partie sur in developing ideas central to under­ later (Penfield and Rasmussen, 1950). le resultat de Vetude du systeme somato- standing cortical mechanisms ap­ Woolsey and Fairman (1946) found sensitif. Les idees de cartes topographiquesplicabl e to all sensory systems. The SII in a number of primates and sub- de colonnes corticales, de specificite ideas of (i) topographic maps, (ii) cor­ primates and hypothesized that the se­ module, ont toutes originees dans Vetude detica l columns, and (iii) modality cond somatosensory map was an ce systeme, pour etre ensuite appliquees aux systemes auditifs et visuels. Re'cem- specificity originated in this sensory evolutionarily more primitive projec­ ment des changements fondamentaux se system and were later applied to the tion of the body surface that had been sont produits dans notre comprehension auditory and visual systems. Now, superceded by a newer projection to SI. des fonctions somatosensitives et corticales, after several decades of relative con­ These classical experiments il­ ces concepts nouveaux s'appliqueront bien-stancy, our ideas about somatosensory lustrated the regularity of the represen­ tdt aux autres systemes. Le present article cortical function have begun to change tation of the body surface on the cor­ detaille ces developpements.
  • Taste and Smell Disorders in Clinical Neurology

    Taste and Smell Disorders in Clinical Neurology

    TASTE AND SMELL DISORDERS IN CLINICAL NEUROLOGY OUTLINE A. Anatomy and Physiology of the Taste and Smell System B. Quantifying Chemosensory Disturbances C. Common Neurological and Medical Disorders causing Primary Smell Impairment with Secondary Loss of Food Flavors a. Post Traumatic Anosmia b. Medications (prescribed & over the counter) c. Alcohol Abuse d. Neurodegenerative Disorders e. Multiple Sclerosis f. Migraine g. Chronic Medical Disorders (liver and kidney disease, thyroid deficiency, Diabetes). D. Common Neurological and Medical Disorders Causing a Primary Taste disorder with usually Normal Olfactory Function. a. Medications (prescribed and over the counter), b. Toxins (smoking and Radiation Treatments) c. Chronic medical Disorders ( Liver and Kidney Disease, Hypothyroidism, GERD, Diabetes,) d. Neurological Disorders( Bell’s Palsy, Stroke, MS,) e. Intubation during an emergency or for general anesthesia. E. Abnormal Smells and Tastes (Dysosmia and Dysgeusia): Diagnosis and Treatment F. Morbidity of Smell and Taste Impairment. G. Treatment of Smell and Taste Impairment (Education, Counseling ,Changes in Food Preparation) H. Role of Smell Testing in the Diagnosis of Neurodegenerative Disorders 1 BACKGROUND Disorders of taste and smell play a very important role in many neurological conditions such as; head trauma, facial and trigeminal nerve impairment, and many neurodegenerative disorders such as Alzheimer’s, Parkinson Disorders, Lewy Body Disease and Frontal Temporal Dementia. Impaired smell and taste impairs quality of life such as loss of food enjoyment, weight loss or weight gain, decreased appetite and safety concerns such as inability to smell smoke, gas, spoiled food and one’s body odor. Dysosmia and Dysgeusia are very unpleasant disorders that often accompany smell and taste impairments.
  • Touch and Temperature Senses

    Touch and Temperature Senses

    1 In press in Proceedings of the Association for Biology Laboratory Education (ABLE), 2004 Touch and Temperature Senses by Charlie Drewes Ecology, Evolution & Organismal Biology Iowa State University Ames, IA 50011 (515) 294-8061 [email protected] http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/ Biographical: Charlie Drewes received a BA in biology from Augustana College (SD) and his MS and PhD in zoology from Michigan State University. Currently, he is a professor in Ecology, Evolution and Organismal Biology at Iowa State University. His research focus is on rapid escape reflexes and locomotion, especially in oligochaete worms. Charlie teaches courses in invertebrate biology, neurobiology and bioethics. During summers, he leads hands-on, residential workshops for high school biology teachers at Iowa Lakeside Lab. In 1998, he received the Distinguished Science Teaching Award from the Iowa Academy of Science and, in 2002, he received the Four-year College Biology Teaching Award from the National Association of Biology Teachers. Abstract: This investigation focuses on the sensory biology of human touch and temperature reception. Students investigate quantitative and qualitative aspects of touch-sensory functions in human skin. Values for two-point discrimination are compared to Weber’s original data. Also, novel materials and methods are introduced for investigating the functional organization of cold sensory reception in human skin, including: (a) estimation of sensory field size for single cold-sensory fibers, (b) demonstration of the discontinuous distribution of cold-sensory fibers in skin, and (c) estimation of the density of cold-sensitive fibers per unit area of skin. Tactile and thermoreceptor functions are related to underlying neuroanatomy of peripheral and central neural pathways.
  • Sensory Receptors

    Sensory Receptors

    Laboratory Worksheet Exercise: Sensory Receptors Sense Organs - Sensory Receptors A sensory receptor is a specialized ending of a sensory neuron that detects a specific stimulus. Receptors can range from simple nerve endings of a sensory neuron (e.g., pain, touch), to a complex combination of nervous, epithelial, connective and muscular tissue (e.g., the eyes). Axon Synaptic info. Sensory end bulbs Receptors Figure 1. Diagram of a sensory neuron with sensory information being detected by sensory receptors located at the incoming end of the neuron. This information travels along the axon and delivers its signal to the central nervous system (CNS) via the synaptic end bulbs with the release of neurotransmitters. The function of a sensory receptor is to act as a transducer. Transducers convert one form of energy into another. In the human body, sensory receptors convert stimulus energy into electrical impulses called action potentials. The frequency and duration of action potential firing gives meaning to the information coming in from a specific receptor. The nervous system helps to maintain homeostasis in the body by monitoring the internal and external environments of the body using receptors to achieve this. Sensations are things in our environment that we detect with our 5 senses. The 5 basic senses are: Sight Hearing Touch Taste Smell An adequate stimulus is a particular form of energy to which a receptor is most responsive. For example, thermoreceptors are more sensitive to temperature than to pressure. The threshold of a receptor is the minimum stimulus required to activate that receptor. Information about Receptor Transmission Sensory receptors transmit four kinds of information - modality, location, intensity and duration.
  • The Effect of Carotid Chemoreceptor Inhibition on Exercise Tolerance in Chronic Obstructive Pulmonary Disease: a Randomized-Controlled Crossover Trial

    The Effect of Carotid Chemoreceptor Inhibition on Exercise Tolerance in Chronic Obstructive Pulmonary Disease: a Randomized-Controlled Crossover Trial

    Respiratory Medicine 160 (2019) 105815 Contents lists available at ScienceDirect Respiratory Medicine journal homepage: http://www.elsevier.com/locate/rmed The effect of carotid chemoreceptor inhibition on exercise tolerance in chronic obstructive pulmonary disease: A randomized-controlled crossover trial a,b � a,c a a Devin B. Phillips , Sophie E. Collins , Tracey L. Bryan , Eric Y.L. Wong , M. Sean McMurtry d, Mohit Bhutani a, Michael K. Stickland a,e,* a Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada b Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Canada c Faculty of Rehabilitation Medicine, University of Alberta, Canada d Division of Cardiology, Faculty of Medicine and Dentistry, University of Alberta, Canada e G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, Alberta, Canada ARTICLE INFO ABSTRACT Keywords: Background: Patients with chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory COPD response to exercise, contributing to exertional dyspnea and exercise intolerance. We recently demonstrated Exercise tolerance enhanced activity and sensitivity of the carotid chemoreceptor (CC) in COPD which may alter ventilatory and Carotid chemoreceptor cardiovascular regulation and negatively affect exercise tolerance. We sought to determine whether CC inhibi­ Dyspnea tion improves ventilatory and cardiovascular regulation, dyspnea and exercise tolerance in COPD. Methods: Twelve mild-moderate COPD patients (FEV1 83 � 15 %predicted) and twelve age- and sex-matched healthy controls completed two time-to-symptom limitation (TLIM) constant load exercise tests at 75% peak À À power output with either intravenous saline or low-dose dopamine (2 μg⋅kg 1⋅min 1, order randomized) to inhibit the CC.
  • The Neurophysiology of Backward Visual Masking: Information Analysis

    The Neurophysiology of Backward Visual Masking: Information Analysis

    The Neurophysiology of Backward Visual Masking: Information Analysis Edmund T. Rolls, Martin J. Tovée, and Stefano Panzeri University of Oxford Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/11/3/300/1758552/089892999563409.pdf by guest on 18 May 2021 Abstract ■ Backward masking can potentially provide evidence of the to the stimulus. The decrease is more marked than the decrease time needed for visual processing, a fundamental constraint in ªring rate because it is the selective part of the ªring that that must be incorporated into computational models of vision. is especially attenuated by the mask, not the spontaneous Although backward masking has been extensively used psycho- ªring, and also because the neuronal response is more variable physically, there is little direct evidence for the effects of visual at short SOAs. However, even at the shortest SOA of 20 msec, masking on neuronal responses. To investigate the effects of a the information available is on average 0.1 bits. This compares backward masking paradigm on the responses of neurons in to 0.3 bits with only the 16-msec target stimulus shown and a the temporal visual cortex, we have shown that the response typical value for such neurons of 0.4 to 0.5 bits with a 500- of the neurons is interrupted by the mask. Under conditions msec stimulus. The results thus show that considerable infor- when humans can just identify the stimulus, with stimulus mation is available from neuronal responses even under onset asynchronies (SOA) of 20 msec, neurons in macaques backward masking conditions that allow the neurons to have respond to their best stimulus for approximately 30 msec.