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Sensory Systems PowerPoint Presentation

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Description : Check out this medical PowerPoint presentation titled "SENSORY SYSTEMS".

This medical PowerPoint presentation is about the sensory systems, responsible for detecting, processing, and interpreting sensory information from the environment. These systems include:

Visual system: responsible for processing visual information from the eyes, including color, shape, and movement.
Auditory system: responsible for processing sound waves from the ears, including pitch, volume, and location of the sound source.
Gustatory system: responsible for processing taste information from the tongue, including sweet, sour, salty, and bitter.
Olfactory system: responsible for processing smell information from the nose, including the identification of different odors.
Somatosensory system: responsible for processing touch, pressure, temperature, and pain sensations from the skin, muscles, and internal organs.

These sensory systems work together to provide us with a comprehensive understanding of our environment and to help us interact with it effectively. The information gathered by these systems is transmitted to the brain, where it is processed and integrated to produce our perceptual experiences.

Tags : sensory systems, Visual system, Auditory system, Gustatory system, Olfactory system, Somatosensory system

Published on : Jun 23, 2023 | Views : 1608 | Downloads : 3

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Slide 1-

CHAPTER 3SENSORY SYSTEMS
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Disorders of sensory systems Deficits Sensory organ Sensory nerves Central nervous system Hyperactivity Central neuropathic pain Tinnitus Tingling Normal response that is redirected Pain from touch Dizziness and vertigo from head movements
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Disorders of sensory systems Reduced sensitivity Hearing loss Visual impairment Incorrect response Hyperacusis Distorted sounds Allodynia Hyperpathia
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Disorders of sensory systems Impaired conduction of the physical stimulus to the receptors Impaired function of receptors Impaired function of sensory nerves Impaired or changed function of the central nervous system
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Reduced sensitivity Often caused by disorders of the sense organs Injury to afferent nerves
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Hyperactive sensory disorders Increased sensation of physical stimuli Altered sensation of physical stimuli Sensation without any physical stimulation
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General organization of sensory systems Conduction of the physical stimulus to the receptors Sensory receptors Sensory nerves Central nervous system
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Sensory transduction A physical stimulus generates a receptor potential The receptor potential is a graded potential The receptor potential is conducted electrotonically to the spike generation site
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Bipolar receptor cells (taste)
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Initiation of nerve impulses Occurs at the first node of Ranvier
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Two different types of receptors, with bipolar nerve fibers
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Sensory transduction (mechanoreceptor in a muscle)
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Central nervous system
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HUMAN Mouse Chick
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Auditory nervous system Ascending auditory pathways From: Møller, 2005
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Two different ascending sensory pathways have been identified: The classical systems The non-classical systems
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From: Møller: Sensory Systems, 2003 Classical auditory pathways Non-classical auditory pathways
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Non-classical auditory pathways Receive input from the somatosensory system Use the dorsal part of the MGB From: Møller, 2005
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The classical ascending pathways The number of nuclei is different in different sensory systems Use ventral thalamic nuclei that project to primary sensory cortices Neurons processes only input from of one sensory modality
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From: Møller, 2005 Visual system Classical ascending pathways Non-classical ascending pathways
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The nonclassical pathways Use dorsal and medial thalamic nuclei that project to secondary cortices and to other parts of the CNS Receive input from more than one sense
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Somatosensory pathways Classical pathways Non-classical pathways From: Møller, 2005
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Processing after primary sensory cortices Integration of input from different sensory systems occurs in association cortices Parallel processing Stream segregation
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The neocortex has six layers
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Simplified diagram of the connections to and from the different layers of the cerebral cortex From: Møller: Sensory Systems, 2002
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Maps Tonotopic Somatotopic
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SURFACE VIEW
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LOWER BODY IS REPRE-SENTED NEAR THE MIDLINE
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Tonotopic organization in the CN of a cat, as an example of tonotopic organization in the auditory system
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Tonotopic organization in the CN of a cat, as an example of tonotopic organization in the auditory system
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Parallel processingStream segregation
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Parallel processing: Cochlear nucleus
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Function of sensory nervous systems Processing of sensory input at the peripheral level Convergence (spatial integration) Interplay between inhibition and excitation
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Spatial integration: Receptive field of a dorsal column nucleus cell
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Convergence of input to a secondary neuron
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Lateral inhibition
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Central processing of sensory information Each stage enhances or suppress specific Information
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Parallel processing:The same information is processed in different structuresStream segregation:Different kinds of information is processed in different structures(“What” and “Where”)
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Processing after primary sensory cortices Integration of input from different sensory systems occurs in association cortices
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From: Møller: Sensory Systems, 2003 Stream segregation Cortical circuitry Dorsal stream “where” Ventral stream “what”
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Sensory information can reach other regions than sensory regions Motor systems Memory Emotional brain (limbic system)
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From: Møller, 2005 Two different routes to the Amygdala from a sensory system
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From: Møller: Sensory Systems, 2003 Connections from a sensory system to the amygdala “the high route”
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Connections from a sensory system to the amygdala “the low route” From: Møller: Sensory Systems, 2003
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From: Møller: Sensory Systems, 2003 Connections from the amygdala
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Hypoactive sensory disorders Loss of sensitivity Hearing loss Poor vision Numbness Loss of vestibular (balance) function
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HEARING LEVEL AT 4 kHz NOISE IMMISSION LEVEL
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Courtesy of M. Charles Liberman Genetic, epigenetic and environmental Causes (and a stochastic component ?)
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Age-related hearing loss
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Normal variations in hearing loss of 70 year old individuals
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Variations in speech discrimination in 70 year old individuals
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Hearing loss in Ménière's disease
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Effect of surgical injuries to the auditory nerve: Large decrease in speech discrimination
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Hyperactive sensory disorders Tinnitus Paresthesia Phosphenes Phantom sensations Central neuropathic pain
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Subjective and objective tinnitus Different forms of tinnitus have very different effects on an individual’s life
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Similarities between chronic pain and severe tinnitus
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There are many forms of tinnitus Mild tinnitus: Does not interfere noticeably with everyday life Moderate tinnitus: May cause some annoyance and may be perceived as unpleasant Severe tinnitus: Affects a person’s entire life in major ways Patients’ own perception varies between mild, moderate and severe (disabling)
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Important to have words for disorders We cannot think about matters that do not have names The same words is used to describe very different forms of tinnitus and pain Using the same names for fundamentally different disorders is a disadvantage in treating these disorders
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How prevalent is severe tinnitus? Some statistics show 50 million people have tinnitus in the USA The prevalence of severe (bothersome) tinnitus is infrequent at young age; it reaches 12-14% for people at age 65 according to one study
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How prevalent is severe pain? Some pain was reported by 86% of individuals above the age of 65 (Iowa study, 1994) The prevalence of severe pain was 33% for people at age 77 and above (Swedish study, 1996)
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Severe tinnitus affects a person’s entire life in major ways Prevents or disturbs sleep Interferes with or prevents Intellectual work Often accompanied by altered perception of sound
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Severe pain affects a person’s entire life in major ways Prevent or disturb sleep Interfere with or prevents intellectual work May cause suicide May involve limbic structures causing affective reactions Often accompanied by abnormal sensations from touch
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Severe tinnitus is often accompanied by altered perception of sound Sounds are distorted Sounds have exaggerated loudness (hyperacusis) Sounds are unpleasant Sounds are painful and arouse fear (phonophobia)
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Little is known about the cause of subjective tinnitus Noise exposure Ototoxic antibiotic Acoustic tumors
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The sympathetic nervous system is involved in some forms of severe tinnitus Some forms of tinnitus can be cured by sympathectomy
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Deprivation of sound can cause changes in neural processing such as change in temporal integration Expression of neural plasticity
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The anatomical location of the abnormality that cause chronic pain and tinnitus may be different from that to which the pain or the tinnitus is referred
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The abnormal neural activity that causes symptoms are not generated at the location where the symptoms are felt Examples: Phantom pain Tinnitus with severed auditory nerve
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The tinnitus in some patients can be modulated by stimulation of the somatosensory systems (such as by electrical stimulation of the median nerve)“cross-modal” interaction
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Non-classical auditory pathways Receive input from the somatosensory system Use the dorsal part of the MGB From: Møller, 2005
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Other signs of involvement of the somatosensory system Gaze related tinnitus Neck muscles and tinnitus TMJ and tinnitus Sensation of sound from touching the skin
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Connections between spinal C2 segment and the dorsal cochlear nucleus Can explain why electrical stimulation of the skin behind the ears can modulate tinnitus
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Symptoms and signs of neuropathic pain and severe tinnitus Strong emotional components Depression High risk of suicide
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Severe tinnitus is often associated with affective (mood) disorders Depression Phonophobia
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The amygdala is involved in fear and other mood disorders
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Connections from the auditory system to the amygdala Cortical-cortical connections (the “high route”) Subcortical connections (the “low route”)
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From: Møller, 2005
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CONCLUSION ACTIVATION OF NON-CLASSICAL ASCENDING SENSORY PATHWAYS CAN CAUSE SYMPTOMS AND SIGNS OF SEVERAL DISEASES
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Neural plasticity play greater role in generating symptoms and signs than previously assumed Plastic changes are reversible Treatments without medicine and surgery may alleviate pain and tinnitus
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Therapy There is no treatment for tinnitus that is comparative to common pharmacological treatment of pain. Treatment of tinnitus has been mainly benzodiazepines (GABAA agonists)
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Reversal of neural plasticity “TENS” (transderm electric nerve stimulation) has been used for many years in treatment of chronic pain Recently sound stimulation in various forms have been introduced in treatment of severe tinnitus
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Stimulation of somatosensory system can relieve tinnitus Electrical stimulation of the ear and of the skin behind the ears have been used to treat tinnitus Electrical stimulation of the auditory cortex is in a stage of development Few systematic studies of efficacy have been published
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