KIN 255 - Cumulated Notes PDF

LECTURE I INTRODUCTION TO THE NERVOUS SYSTEM TheCNSintegrates stimulus transmitsmotorresponse NSmadeupof 50 neurons 50 glialcells Glialcells ProvideSupport Suppliesnutrients 02 insulates neurons cleandebris Oligodendrocytes CNS SchwannCells PNS ÉfÉptcPotential Gradedelectrochemi...

LECTURE I INTRODUCTION TO THE NERVOUS SYSTEM TheCNSintegrates stimulus transmitsmotorresponse NSmadeupof 50 neurons 50 glialcells Glialcells ProvideSupport Suppliesnutrients 02 insulates neurons cleandebris Oligodendrocytes CNS SchwannCells PNS ÉfÉptcPotential Gradedelectrochemical responseconvergesat axonhillock integration Actionpotential AP All ornothingelectrochemicalresponsedueto Changes in membranepotentialdue to ionPermeability Greyversuswhitematterm Greymatte.rs Groupsof cell bodiesdendrites terminalendings nuclei CNS ganglia PNS Site of integration and transformation WhiteMatter Bundleofmyelinatedaxon Pathways connecting areas ofgreymatter foundat difflevels of nervoussystem brain grayoutsidewhiteinside spinalcord whiteoutsidegreyinside ain Components of the NS Thrainerroussystemens SpinalCord brainstem withinSkeleton Brain divided into Hindbrain Midbrain forebrain PeripheralNervous System PNS Outsideskeleton Dividedintosomatic skeletalmuscle autonomic organssmoothmuscle glands Enteric GI tractbloodflow AutonomicNervous systemdividedinto sympathetic NS fightorflight ParasympatheticNS rest digest ff Ff.EEEfEding to braincaggerent descendingfrombrain efferent Entry exit to fromPNS CNScomponent BrainStem TFectivelfregerstoponsmedilla hindbrain midbrain Contains 12 Cranial nerves innervating eyeshead neck uppertrunk Criticalto autonomicfunction alertness eye headmovements on 10 ofbrain size yetcontains 50 ofbrains neurons containsdenseafferent efferentconnections w brainstem cortex ask.EE E fEftEEEaiamusa descendingmotortracts Contributes to the control of movementlearning Cognition emotions Gangliadespitebeing in CNS wfffferentithalamusadypothalamummer Relay area between cortexandCNS Plays a role in alertness Essential to sensorimotor Processing exceptsmell Hypothalamus Contributes tocontrol ofinternalbodyfunctions homeostasis Linksnervoussystem endocrineSystem fsffffetsferebralcortexn.rs Responsible for higherorderthinking behaviour executiveprocesses Action Control bodymovement eye movement a speech Occipital lobe Receives visualinput Processes colour motion environment Parietallobe Receives Processes sensory information relatingtouch taste ReceivesProcessed visual auditoryinfo from occipital temporalcortices Integrates info from senses for objectperception motorcontrol Temporal lobe Receives raw auditoryinputfromthalamus earlyProcessingofsound Storage retreival of memories Combinesvisual info intoobjectPerceptions EmotionProcessing groupingofobjects Amygdala hippocampus contributesto memorystorage Brodmann Area Region of cortexgrouped by Cytoarchitecture mirrorsfunctioncreating link betweenBrodmann area functional cortextaxonomy Primary vs Secondary vs Association Cortex Primary firstarrival ofsensory input or laststop for motoroutput Secondary ReceivesProcessed information AssociationArea Secondary reflects integration ofinformation  LECTURE 2 SENSORY RECEPTORS or cell endings that convert stimulus to electricalPotentials that can be transmitted and interpreted by nervous system Mechanoreceptors Convertmechanical energy Photoreceptors Converts lightenergy Chemoreceptors Converts chemical energy Thermoreceptors converts thermal energy Mechanism stimulus energy leads to change in electrochemicalstate j e Receptor can represent stimulus by h Type of stimulus digg sensory diss type stimulus Onset offset duration of stimulus receptoractivity depends on Presence of stimul i Intensity of the stimulus adjusting howmany action potentials are triggered Perunittime Location ofstimulus Stimulus Modality Toothictiorption changeto external or internal state of the body Movement Proprioception Sense of bodies position Orientation equilibrioception sense of movement Position in relation to gravity Hearing audioception sense of environment from sound waves sight opthalmoception Sense of objects from visible light smell olfacoception chemical odorants in nasal cavity Taste gustaoception substances chemically react in mouth Pain nociception Pain due to injury damage Somatosensory any Mechanoreceptor thermoreceptor or nociceptor in skin fatty tissue beneath Skin Muscle or Msk tissue Lig tendon joint Capsule Vestibular Mechanoreceptors within labyrinths of inner ear visual Photoreceptors located in retina Auditory Mechanoreceptors in cochlea propertiesofPotenti fshtefinfsdstf.nunge fÉffIeswdptingeetf Vigorous but transient response to changes in stimulus energy Optimal to detect rate ofchange in stimulus energyintensity Slow adapting Measured but sustained response while stimulus energy is constant Reflects actual stimulus energyintensity Photoreceptors AbsorbPhotons from lightwavelength leading to chemical reaction thatgenerates receptor potential Pigment absorbs light Initiates second messengerpathways that closes Natchannels decreasing amp of receptor potential less neurotransmitter is released when receptorpoten reaches end of receptor Do not directly inShence Sensory nerve acts via intermediary bipolarcell  MODULE 3 CENTRAL AND PERIPHERAL AFFERENT PATHWAYS IEFffffffaffenftnff.fr Amount of insulation around the eaves cars depends on Prevents axon of afferent neuron ions from leaking out of axonmyelin sheath Diameter of the axon of aggerent neuron Largerdiameterprovides room for axons to flow Proprioceptive afferent neurons are the quickest transmitters of afferent information EÉtÉÉÉ to tjgfatter region for sensory system eventually converges in associatio areas generate action Divergence Same inputseparates disperses to multiplelocations Convergence Multiple inputsproject to commonlocation Topographic orderedProjection of a sensory Surface retina or skin within nuclei neuron in CNS foundthroughout all levels in CNS Ipsilateral belonging to or occurring on same side the body of contralateral belonging to or occurring on opposite side of the body ff.tn Eprojects to two ParallelPathways Geniculostriate visual System 90 of fibers Primary visual Pathway Retina Lateralgeniculate LGN thalamic nucleus Primary visual VI cortex Tectopulvinar Visual system110 of fibers Secondary VisualPathway Retina Superiorcollious midbrain Pulvinar nucleus of thalamus Information from contralateral visual field cross midlineat optic chiasm Lefthemigield Rightthalamus v2 Right hemigield Leftthalamus v1 V1 is mirror of visualenvironment Lesionog right optic nerve assets Épin it strategies right side Lesion of optic chiasm results in loss ofPeripheral view tunnel vision niai.mucsn88aegst visual space Iysotinffh.tn tficti tm Ytws Dorsal stream relate visual environmket 7858 dnyÉ'vision for action where or How ventral stream emphasize objecting.gg vision for perception what in fmaesmsifysgstImh Prosopagnosia inabilityto recognizefaces is associated with damage to ventralvisual Pathway  axons formingvestibular nerve ccnviiiiriiijpto.ge ss It L is if in Ia.iemibntiuclear complex Somatosensoryme In somatosensory system mechanoreceptors are specialized cells that project to an afferent neuron or are part of the afferent neuron itself somatosensory nerves exceptfromhead enter spinal cord via dorsal horn Nerves from headformtrigeminal nerve CN V Somatosensory nerves layertoform the ascendingPathways but also have many divergentprojections in spinal cord to help facilitate reflexes coordination among muscle groups Cell bodies of sensory neurons are outside spinalcord in dorsal rootganglion Nerve bundles in PosteriorColumnPathwayConveyfine touch Vibration proprioceptive afferentinfo Third order neuron Axon that project fromthalamic nuclei to Primary somatosensory cortex Second order neuron axon that crosses bodymidline in medulla Projects to thalamic nuclei First order neuron Axon that Projects from receptor to medulla AnteriorSpinothalamic tract Anterior medial Crude Poorly localized information about touch LateralSpinothalamic tract Information about noxious stimuli temperature Dorsal spinocerebellar tract IDSCT Projects to the inferior peduncle of cerebellum Proprioceptive info from lower limbs spindle fibers via afferent neurons Rostral spinocerebellar tract RSCT Projects to the inferior Peduncle of cerebellum Proprioceptive info from upper limbs Ventral spinocerebellar tract VSCTI Projects to the superior Peduncle of the cerebellum Proprioceptive info from lower limbs Golgitendon organs via Ib aggerent neurons  MODULE 4 STIMULUS EVOKED RESPONSES AND SIMPLE REFLEXES Stimulus evoked behaviour involuntary automatic immediate consequence of stimulation Stimulus driven stimulus defines the characteristics of response Stimulus released Characteristics of response can be independent of some stimulus Characteristics Many are examples of reflexes Produced as direct automatic relativelyimmediat response to stimulation ways to measure differentelements of the stimulus responsetransformation Behavioral measures of the stimulus responseProcess timingaccuracy stimulus response characteristic response modifiability Electrophysiology assessment of the stimulus response pathways H reflex evoke Potentials brain hemodynamics non invasive brain stimulation Timing Tapsedtime between diggpoints of stimulus to response process provides info about each specific partof the process conduction time time it takes to conduct signal along axon Pathways Synapse time time it takes for info to be exchangedby neurons processing time Reaction time time btw stim onset motor system response latency orpremoto Movement time btw onset of motor system response and movement outcome Response time Reaction time movement time btw stim movement outcome 4f ffffgngreactiontimem. n More choices longer reaction time Hicks law logarythmic relationship I keep it simplestupid kiss principle Simple reaction time one stimulus one response Choice reaction time one stimulus multipleresponses stimulus response compatibility R T is quicker the closer stimulus is in relation to response stimulusmodality Stimulus modalities takes diff amount of time to be identified and associated w reaction stimulus intensity predictability More intense stimuli quicker response time knowing when response is required leads to quickerresponse Preloaded response tEsgPÉh fnapsesdirectly wt motor Extragosal fibers neuron one synapse contractile ex stretch reflex responsible forgenerating force Intragosal specialized muscle spindlefibers that detectstretch More extragusal fibers than in tragusal afferent nerves diverge to act on motorneurons innervating multiple extragusal fibers many requires Coordinated action w agesftp.psyneygifkp mono synaptic antagonist disynaptic Homonymous reflex pathway HORP Afferent excitation of sensory neuron excite motor neuron projecting back to same muscle Heteronymous reflexPathway HERP afferent excitation of sensory neuron excites inhibits motor neuron projecting to diff muscle Alphamotor neurons Innervate extragusalfibers to shorten Ap or lengthen AP Gammamotor neurons specialsegments at the end of Intragusal fiber to keeptaught as muscle Contracts Pulls ion Channels open to generate receptorpotential Fusimotordrive Musclespindle fibers gamma motor neuron fusimotor system Alpha gamma coactivation Coordinated action during muscle contraction Tonic or fusimotor bias Increase in spindle fibre tension due to alpha motorCoactivation during contraction Modification of stimulus responserelationship Changestogamma motor neuron activity changesspindlereceptorsensitivity alters tautness ofspindle samestretchresults in weaker afferent response Inhibitthe reflex decreasesstrengthof the effectofsensoryafferenton motor neuron gai Facilitatethereflex increasethe gain at the sensory to motor synapsel MODULE 4 STIMULUS EVOKED BEHAVIOUR WEEhys.IE ltorolto assess the stimulus response characteristic of myotatic reflexpathways stimulatingthe nerve rather than mechanicallystretching the muscle removesinfluence ofspindlefiberProvides a controlled inputto study stim response relationship Amplitude is sensitive to intensitystimulus Hreflex motor response byelectricalstimulus on afferentsensory nerve M wave Motor response byelectrical stimulus on efferentmotor nerve Inversemyotaticreglexen AKA Golgitendon organ GTO reflex strong excitationof lb aggerentdue to extreme muscle tension overrides the alpha motor neuron excitation of the muscle Initial inverse myotaticreflex done w muscle at rest alpha motor neuron inhibition however excitation of Ib afferent nerve actually facilitates alpha motor neuron excitation ftp.gaptteptathgekfires ipsilateral contralateral muscle coordination stimulus initiates pain receptors sensory neuron activatesmultiple Interneurons Ipsilateral motor neurons toflexorexcited ipsilateral flexor Contracts Contralateral mn to extensor excited extension of leg Eye Movements Fovea is the portionof retina w highestdensity of cone photoreceptor responsible for high visual acuity Visual axis straightPath frompointoffixation to fovea changes optical axis straightlinepassingthrough center of lens Direction of Gaze directionof visual axis relative to environment Gaze angle angular measurement ofdirection ofgaze in horizontal or verticalplane Effectors extraocular muscles controlhorizontalvertical rotational movement of the eye Abducens nerve V1 Lateral rectus Oculomotor nerve 111 Medial rectus Superior rectus inferior rectus Inferioroblique Trochlear nerve IV Superioroblique Classification of movements Conjugate or version Coordinatedeye movement in same direction through same angle Disconjugate or vergence coordinated eye movement in opposite directions throughmirrored angles Classes Vestibulo ocularreflex stabilizes gaze in responseto headrotation Optokinetic reflex Combination of slow fast eye movement to keepmoving scene stationary Saccades Rapid ballistic eye movementchangingPointof fixation SmoothPursuit eye movements that keeps eyes fixated on movingobject vergence Coordinated disconjugated movement of botheyes to obtain or Maintain binocular vision vestibulo ocular reflex VOR Rapidcompensatory eye movements to stabilize direction of the gaze Controlled by nuclei in the brain stene Eyes rotate to oppositedirection of head cancelling out velocity no InputHeadrotation vestibular nerve output extraocularmuscle activity abducens oculomotor trochlear nerves Afterabducens Agonistmuscle s leftmedialrectus via oculomotornucleus rightlateral rectus via abducensnuclei Antagonistmuscles excitatoryafferentinputexcitesinhibitoryinterneurons to relax left lateral rectus rightmedial rectus Saccades Rapid movement 900 or 75mph of eyes in samedirection a involvedparietal dentalcortices exogenously driven bysomethingoutsidethebody endogenouslydriven Input retina output oculomotornuclei Exogenously driven Express saccade bypasses cortex 70 100ms Prosaccades reflex saccades traversestheCortes longerroutethroughvisual Cortex 150 200ms Endogenously driven Predictive saccade stimulusexpected but not yet occurring memory guided saccade stimulus was located but not anymore Anti Saccade oppositedirection inhibition of reflex saccade sequence fixate on a series ofPoints in space learned MODULE G MODULATION OF STIMULUS EVOKED BEHAVIOUR Mechanism of Modulation Post Synaptic potential or action Potential spatialsummation Aggregation ofPost SynapticPotentialsarising from multiple separate synapses can be inhibitory Temporal summation Aggregation of multiplePost synapticPotentials occurring close in time