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HMB200H1 (69)
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Notes on Yeoman's paper "Tactile, acoustic and vestibular systems sum to elicit the startle"

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Department
Human Biology
Course
HMB200H1
Professor
John Yeomans
Semester
Winter

Description
Jan 19 2012No generally accepted view of fn f acoustic startle responseNotes on Yeomans Tactile acoustic Could fn to interrupt ongoing bhvrsand vestibular systems sum to elicit the Might prob be protective response since startle reflexbhvr pattern consists of reactions likely to prevent serious injury from attackbut Abstractdoes not explain relationship btwn acoustic Startle reflex elicited by intense tactile stimuli attacksinjuryacoustic or vestibular stimuliFast mechanoreceptors in each modality can Acoustic startle often maladaptive in noisy respond to skin or head displacementurban lifeIn each modality stimulation of cranial nerves If elicited during coordinated motor activity or primary sensory nuclei evoke startlelike interferesresponseBg noise increases sensitivity to startling stimuliRats most sensitive site in ventral spinal Disrupts sensorycognitive processingheart trigeminal pathway inputs from dorsal facerate increases other sympathetic activationCrossmodal summation stronger than intramodal temporal summationconvergence Tactilevestibular systems can also activate of acoustic vestibulartactile info important startlefor eliciting startleCrossmodal summation of acoustic tactileSummation declines sharply if crossmodal vestibular more effective than singlemodality stimuli not synchronoussummationHead impact stimuli activates trigeminal Evidence suggests critical survival fn in acousticvestibular systems togetherprotecting against blowsmaybe protects body from impact stimulievolutionary principle for brainstem ndIn each primary sensory nucleus large 2order organizationneurons project to pontine ret formation giant Compare circuits for each modalityneurons critical for acoustic startle reflexpropose where summation occurs btwn In vestibular nucleus sites startlelike responses themappear to be mediated mainly via vestibulospinal tract not reticulospinal tractStimuli that elicit startleSummation btwn vestibulospinalStartlelike responses bilaterally symmetric reticulospinal pathways mediating startlein responses of whole body at very short latencies ventral spinal cordevoked by strongsudden acoustic tactile or vestibular stimuli cats ratsIntroductionVery bright lightsfull eyeblink responses or Startle reflex most extensive of all reflexesEMG response in eyeclosure muscles humansActivates hundreds of competing muscles Olfactory or visual stimuli alone no known to thruout body in stereotyped wayreliable evoke wholebody startle responsesEasy to observe easy to elicit w appropriate acoustic stimuliAll 3 modalities use fast ionotropic Short latency of acoustic startle reflex useful mechanorecsin identifying neuronscircuits mediating Somatosensory displacement of skinmusclesthe responseVestibular head displacementsmovements of inner ear fluids otoconia to activate hair cell Can be modified in several waysprovided mechanorecsmodel system to study plasticitylearningAuditory acoustic stimuli conduct via airIncreased by threatening stimuli ex pics bonesactivate hair cells in cochleastimuli paired w shock anxiogenic drugs in ratsMechanical actions to body surface may be Reduced by rewarding or threatreducing stimuli important for startleex pornography stimuli associated w rewards Olfactoryvisual systems respond via slow Ganxiolytic drugs in ratsprotcoupled recs Useful probe for studying psych anatomy Pharmacology of emotionsemotional Tactile stimulidisordersElectrical stimulation of skin or trigeminal nerveeffective stimulus for startleactivates Acoustic startle in virtually all mammals studied somatosensory wo any sensory systemsall postnatal stages in humansHumans cutaneousacousticsimilar Must have importantlasting survival valuepattern of muscle activation
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