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PathwaysBrainstem AtlasBrainstem SyndromesSomatosensoryPainMotorAutonomic Nervous SystemOculomotor / OculodominanceHypothalamusLimbicSleepMemoryLanguageNote: If a slide says CLICK, click outside the buttons to advance the animation until CLICK disappears. Otherwise, use the arrow buttons (top right) to navigate between slides.

PathwaysFine TouchPain/TemperatureProprioceptionCorticospinal/CorticobulbarRubrospinal/TectospinalReticulospinalVestibulospinal

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Spinal CordCgracile fasciculuscuneate fasciculusdorsalcolumnssacrallumbarthoraciccervicalSLTdorsal rootganglionFINE TOUCHA fibers (large) enter the spinal cord medial to A, C fibers (small)CLICKMAINSECTION

Medullagracile nucleuscuneate nucleusmediallemniscus2nd ordersacrallumbarthoraciccervicalinternalarcuatefibers2nd orderFINE TOUCHCLICKMAINSECTION

Ponstrigeminal main sensory nucleustrigeminal gangliontrigeminal motor nucleusmedial lemniscus2nd ordersacrallumbarthoraciccervicaltrigeminal sensoryFINE TOUCHCLICKMAINSECTION

Midbrainmediallemniscus2nd orderinferiorcolliculuslateral lemniscussacrallumbarthoraciccervicaltrigeminal sensoryFINE TOUCHCLICKMAINSECTION

Midbrainsuperiorcolliculusred nucleussacrallumbarthoraciccervicaltrigeminal sensorymediallemniscus2nd orderlaterallemniscusFINE TOUCHCLICKMAINSECTION

Forebrainsacrallumbarthoraciccervicaltrigeminal sensoryVPM*VPL*internal capsule3rd orderclick here for horizontal sectionprimary somato-sensory cortexclick hereFINE TOUCHCLICKMAINSECTION* These nuclei are slightly displaced in this view, to illustrate that trigeminal input VPM and body input VPL

Internal Capsule Horizontal Sectionanterior limbposterior limbsacrallumbarthoraciccervicaltrigeminal sensorygenuMAINSECTION

Spinal CordsacrallumbarthoraciccervicalSLdorsal rootganglionLissauers tractsubstantia gelatinosa (RL II)nucleus proprius(RL III, IV)2nd order tracts:spinothalamic/spinoreticular/spinomesencephalicanterior white commissure2nd orderTCPAIN/TEMPA, C fibers (small) enter the spinal cord lateral to A fibers (large)posterior marginalis (RL I)CLICKMAINSECTIONRL = Rexed lamina

Medullasacrallumbarthoraciccervicaltrigeminal sensorytrigeminalspinal tract1st ordertrigeminalspinal nucleusPAIN/TEMP2nd order tracts:spinothalamic/spinoreticular/spinomesencephalicmedullary reticularformationCLICKShow Spinoreticular TractMAINSECTION

Medullasacrallumbarthoraciccervicaltrigeminal sensorytrigeminalafferent1st ordertrigeminalspinal tract1st ordertrigeminalspinal nucleusCROSSPAIN/TEMP2nd order tracts:spinothalamic/spinoreticular/spinomesencephalicSpinoreticular tract in the medullamedullary reticularformationMAINSECTION

Ponstrigeminal ganglionsacrallumbarthoraciccervicaltrigeminal sensorytrigeminal spinal tract1st orderspinothalamic, spinomesenephalictracts2nd orderPAIN/TEMPpontine reticularformationCLICKShow Spinoreticular TractMAINSECTION

Ponstrigeminal gangliontrigeminalafferent1st order[to medulla]sacrallumbarthoraciccervicaltrigeminal sensorytrigeminal spinal tract1st orderspinothalamic, spinomesenephalictracts2nd orderPAIN/TEMPSpinoreticular tract in the ponspontine reticularformationMAINSECTION

Midbrainspinothalamic/spinomesen-cephalic tracts2nd ordersacrallumbarthoraciccervicaltrigeminal sensoryinferiorcolliculusmediallemniscusPAIN/TEMPCLICKMAINSECTION

Midbrainsuperiorcolliculusred nucleussacrallumbarthoraciccervicaltrigeminal sensorymediallemniscusspinothalamic tract2nd orderPAIN/TEMPperiaqueductal gray (PAG)mesencephalicreticularformationCLICKShow Spinomesencepahalic TractMAINSECTION

Midbrainsuperiorcolliculusred nucleussacrallumbarthoraciccervicaltrigeminal sensorymediallemniscusspinothalamic tract2nd orderPAIN/TEMPSpinomesen-cephalic tractperiaqueductal gray (PAG)mesencephalicreticularformationMAINSECTION

Forebrainsacrallumbarthoraciccervicaltrigeminal sensoryVPM*VPL*internal capsule(posterior limb)3rd orderPAIN/TEMPSpinothalamic tract (no evidence for orderly topographic cortical map)primary somato-sensory cortexclick hereCLICKMAINSECTION* These nuclei are slightly displaced in this view, to illustrate that trigeminal input VPM and body input VPL

Spinal Cord - SacralPROPRIOCEPTIONdorsal rootgangliondorsal columnsA fibers (large) enter the spinal cord medial to A, C fibers (small)CLICKMAINSECTION

Spinal Cord - ThoracicClarkes nucleus(dorsal nucleus)T1-L2dorsalspinocerebellartract2nd orderPROPRIOCEPTIONCLICKMAINSECTION

Spinal Cord - Cervicaldorsal rootgangliondorsal columnsdorsalspinocerebellartract2nd orderPROPRIOCEPTIONCLICKMAINSECTION

Medulladorsalspinocerebellartract2nd ordercuneocerebellar tract2nd orderexternal (accessory)cuneate nucleusPROPRIOCEPTIONCLICKMAINSECTION

Medullainferiorcerebellar peduncle2nd orderPROPRIOCEPTIONCLICKMAINSECTION

Cerebellumdeep cerebellar nuclei (see right)medial (fastigius)

interposed (globose + emboliform)

lateral (dentate)mossy fibersinferior cerebellarpeduncle (restiform body)PROPRIOCEPTIONCLICKMAINSECTION

Ponstrigeminal ganglionmesencephalic gangliontrigeminal motor nucleusPROPRIOCEPTIONCLICKMAINSECTION

Forebraininternal capsule(posterior limb)Precentral, prefrontal, postcentral gyricerebral peduncleto lumbar spinal cordto cervical spinal cordto CN motor nucleiCORTICOSPINAL/CORTICOBULBARcorona radiataCLICKMAINSECTION

Midbrainto lumbar spinal cordto cervical spinal cordto CN motor nucleicerebral pedunclesuperiorcolliculusred nucleusoculomotor nucleusCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Midbraintrochlear nucleusinferiorcolliculuscerebral peduncleto lumbar spinal cordto cervical spinal cordto CN motor nucleiCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Ponscorticospinal tractmiddle cerebellar peduncletrigeminal (CN V) motor nucleusto lumbar spinal cordto cervical spinal cordto CN motor nucleiCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Ponsabducens (CN VI) nucleusfacial (CN VII) nucleusThis nucleus is complicated click herecorticospinal tractmiddle cerebellar peduncleto lumbar spinal cordto cervical spinal cordto CN motor nucleiCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Medullahypoglossal (CN XII) nucleusnucleus ambiguouscorticospinal tractto lumbar spinal cordto cervical spinal cordto CN motor nucleiCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

MedullaCROSStrigeminal (CN V) spinal nucleuspyramidal decussationpyramidto lumbar spinal cordto cervical spinal cordCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Spinal Cord - Cervicalventral hornlateral corticospinal tractanterior corticospinal tractto lumbar spinal cordto cervical spinal cordventral white commissureCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTIONCROSS

Spinal Cord - Thoracicto lumbar spinal cordlateral corticospinal tractanterior corticospinal tractCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTION

Spinal Cord - Sacrallateral corticospinal tractanterior corticospinal tractventral hornto lumbar spinal cordventral white commissureCORTICOSPINAL/CORTICOBULBARCLICKMAINSECTIONCROSS

Midbrainrubrospinaltectospinalsuperior colliculusred nucleusRUBROSPINAL/TECTOSPINALdorsal tegmental decussationventral tegmental decussationinput from forebrainCLICKMAINSECTION

Ponstectospinal tractpontine reticular formationrubrospinal tractrubrospinaltectospinalRUBROSPINAL/TECTOSPINALCLICKMAINSECTION

Medullatectospinal tractrubrospinal tractmedullary reticular formationMLFrubrospinaltectospinalRUBROSPINAL/TECTOSPINALCLICKMAINSECTION

Medullatectospinal tractrubrospinal tracttrigeminal (CN V) spinal nucleuspyramidal decussationpyramidrubrospinaltectospinalRUBROSPINAL/TECTOSPINALCLICKMAINSECTION

Spinal Cord - Cervicalrubrospinaltectospinaltectospinal tractrubrospinal tractventral hornRUBROSPINAL/TECTOSPINALCLICKMAINSECTION

Spinal Cord - Lumbarrubrospinalrubrospinal tractventral hornRUBROSPINAL/TECTOSPINALCLICKMAINSECTION

Ponsmedial reticulospinal tractlateral reticulospinal tractpontine reticular formationmedial longitudinal fasciculus (MLF)RETICULOSPINALCLICKMAINSECTION

MedullaMLFmedial reticulospinal tractlateral reticulospinal tractRETICULOSPINALCLICKMAINSECTION

MedullaMLFmedial reticulospinal tractlateral reticulospinal tractRETICULOSPINALCLICKMAINSECTION

Spinal Cord - Cervicalmedial reticulospinal tractlateral reticulospinal tractRETICULOSPINALCLICKMAINSECTION

Spinal Cord - Thoracicmedial reticulospinal tractlateral reticulospinal tractRETICULOSPINALCLICKMAINSECTION

Spinal Cord - Lumbarmedial reticulospinal tractlateral reticulospinal tractRETICULOSPINALCLICKMAINSECTION

Ponslateral vestibular nucleusmedial vestibular nucleusmedial longitudinal fasciculus (MLF)medial vestibulospinal tractlateral vestibulospinal tractVESTIBULOSPINALCLICKMAINSECTION

Medullamedial vestibulospinal tractlateral vestibulospinal tractMLFVESTIBULOSPINALCLICKMAINSECTION

Spinal Cord - Cervicalmedial vestibulospinal tractlateral vestibulospinal tractVESTIBULOSPINALCLICKMAINSECTION

Spinal Cord - Thoraciclateral vestibulospinal tractVESTIBULOSPINALCLICKMAINSECTION

Spinal Cord - Lumbarlateral vestibulospinal tractVESTIBULOSPINALCLICKMAINSECTION

Brainstem AtlasOpen MedullaLower PonsMiddle PonsUpper PonsMidbrainMAIN

Open MedullaCN XII nucleusmedial longitudinal fasciculusmedial lemniscusinferior olivary fiberspyramidsdorsal motor nucleus of the vagusmedial vestibular nucleusnucleus of the solitary tractsolitary tractspinal trigeminal tractspinal trigeminal nucleusnucleus ambiguusinferior olivary nucleusinferior cerebellar pedunclenucleus raphe magnusMedial SyndromeLateral SyndromeMAINSECTION

Open MedullaCN XII nucleusmedial longitudinal fasciculusmedial lemniscusinferior olivary fiberspyramidsdorsal motor nucleus of the vagusmedial vestibular nucleusnucleus of the solitary tractsolitary tractspinal trigeminal tractspinal trigeminal nucleusnucleus ambiguusinferior olivary nucleusinferior cerebellar pedunclenucleus raphe magnusMedial longitudinal fasciculus- Relay for the vestibuloocular reflex- Input from superior/middle/lateral vestibular nuclei- Output to nuclei of CN III, IV, VI

CN XII nucleus- Somatic motor to muscles of tongue Axons exit ventrally between pyramids and olive

Medial lemniscus - Ascending fine touch somatosensory path- Crossed

Spinal trigeminal tract- Primary afferent fibers containing pain/temp info from ipsilateral face

Spinal trigeminal nucleus- Fibers from the spinal trigeminal tract synapse here, then cross and ascend in the spinothalamic tract to VPM

Pyramids Corticospinal tract (descending motor)

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Open MedullaCN XII nucleusmedial longitudinal fasciculusmedial lemniscusinferior olivary fiberspyramidsdorsal motor nucleus of the vagusmedial vestibular nucleusnucleus of the solitary tractsolitary tractspinal trigeminal tractspinal trigeminal nucleusnucleus ambiguusinferior olivary nucleusinferior cerebellar peduncleDorsal motor nucleus of the vagus- Parasympathetic secretomotor neurons

Nucleus of the solitary tract- Receives visceral afferents from CN VII, IX, X (carotid body, carotid sinus, aortic/lung/gut stretch receptors, taste)- Gives rise to fibers projecting to the parabrachial nuclei Roots exit ventrolaterally

Inferior cerebellar peduncle- Fibers to the cerebellum- Includes dorsal spinocerebellar tract and axons from inferior olive

Nucleus ambiguus- Somatic motor to CN IX, X- Supplies muscles of pharynx, larynx- Contains parasympathetic cardiomotor cells

Inferior olivary nucleus- Sends climbing fibers to contralateral cerebellar cortex

Nucleus raphe magnus- Receives input from PAG; projects to dorsal horn and plays role in central modulation of pain

nucleus raphe magnusMAINSECTION

Lower PonsCN VI nucleusmedial longitudinal fasciculusmedial lemniscuspontine fiberscorticospinal tractCN VII motor nucleusmedial vestibular nucleuslateral vestibular nucleussuperior olivary nuclear complexpontine nucleimiddle cerebellar pedunclelateral lemniscusspinothalamic tractraphe nucleiMedial SyndromeLateral SyndromeMAINSECTION

Lower PonsCN VI nucleusmedial longitudinal fasciculusmedial lemniscuspontine fiberscorticospinal tractCN VII motor nucleusmedial vestibular nucleuslateral vestibular nucleussuperior olivary nuclear complexpontine nucleimiddle cerebellar pedunclelateral lemniscusspinothalamic tractraphe nucleiMedial longitudinal fasciculus- Relay for the vestibuloocular reflex- Input from superior/middle/lateral vestibular nuclei- Output to nuclei of CN III, IV, VI

CN VI nucleus- Somatic motor to lateral rectus muscle Nerve exits ventrally between pons, pyramid

Medial lemniscus - Ascending fine touch somatosensory path- Crossed

Lateral lemniscus- Ascending auditory pathways

Middle cerebellar peduncle- Crossed fibers from pons to cerebellar cortex

Corticospinal tract- Descending motor fibers to limbs

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Lower PonsCN VI nucleusmedial longitudinal fasciculusmedial lemniscuspontine fiberscorticospinal tractCN VII motor nucleusmedial vestibular nucleuslateral vestibular nucleussuperior olivary nuclear complexpontine nucleimiddle cerebellar pedunclelateral lemniscusspinothalamic tractMedial/lateral vestibular nuclei- Vestibular relay and reflexes- Primary input to this nucleus is vestibular nerve- Carries info related to balance, linear/angular acceleration

CN VII motor nucleus- Motor to muscles of the face- Facial MNs to UPPER face have inputs from both hemispheres of cerebral cortex- Facial MNs to LOWER face have inputs from only the contralateral cerebral hemisphere Nerve runs dorsally, turns around CN VI nucleus, and exits at junction of pons and olive

Raphe nuclei- Serotonergic; involved in sleep and pain modulation- Caudal nuclei spinal cord- Rostral nuclei (inc. dorsal and median raphe nuclei) all parts of the forebrain

Superior olivary nuclear complex- Use binaural differences in timing and amplitude to localize sound in space

Spinothalamic tract- Ascending pain/temp pathway, crossed

Pontine nuclei- Relays info from ipsilateral cerebral cortex to contralateral cerebellar cortex

raphe nucleiMAINSECTION

Middle PonsCN V main sensory nucleusCN V motor nucleuslateral lemniscusCN V mesencephalic nucleusCN V mesencephalic tractMedial SyndromeLateral SyndromeMAINSECTION

Middle PonsCN V main sensory nucleusCN V motor nucleuslateral lemniscusCN V mesencephalic nucleusCN V mesencephalic tractCN V mesencephalic nucleus- Contains ipsilateral 1a muscle afferents from muscle spindles- Participates in the afferent side of the jaw stretch reflex

CN V motor nucleus- Motor to muscles of the jaw

CN V main sensory nucleus- Receives fine touch sensation from face- Analogous to dorsal column nuclei

Lateral lemniscus- Ascending auditory pathways

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Upper Ponscentral tegmental bundlemedial longitudinal fasciculusmedial lemniscuscorticospinal tractpontocerebellar fiberslocus coeruleusparabrachial regionperiaqueductal grayMedial SyndromeLateral SyndromeMAINSECTION

Upper Ponscentral tegmental bundlemedial longitudinal fasciculusmedial lemniscuscorticospinal tractpontocerebellar fiberslocus coeruleuslocus coeruleussub-coeruleusparabrachial regionperiaqueductal gray

Locus coeruleus- Noradrenergic (this section is stained for tyrosine hydroxylase)- Projections from this nucleus make their target cells more excitable (responsive to afferent input) These cells are part of a brainstem system of cells that project to the entire CNS

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Upper Ponscentral tegmental bundlemedial longitudinal fasciculusmedial lemniscuscorticospinal tractpontocerebellar fiberslocus coeruleusparabrachial regionParabrachial region- Relays visceral afferent info to hypothalamus- Involved in control of respiration, micturition

Periaqueductual gray- Integrates several autonomic reflexes- Involved in fight or flight, quiescence

periaqueductal grayMAINSECTION

Midbrainmedial lemniscussuperior cerebellar pedunclered nucleusCN IIIcerebral pedunclesuperior [inferior is caudal] colliculusperiaqueductal grayClick here to expand this regionTegemental SyndromeVentral SyndromeMAINSECTION

Midbrain - Oculomotor NucleiPAGCN III nucleusEdinger-Westphal nucleusCN IV nucleussuperior colliculusinferior colliculusSuperior colliculus- Visual-motor reflex center

Edinger-Westphal nucleus - Parasympathetic preganglionic neurons- Outputs to pupillary sphincter, ciliary muscle

CN III nucleus- Motor fibers to superior/inferior/medial rectus, inferior oblique, levator palpebraeCN IV nucleus- Motor fibers to trochlear muscle- Fibers exit DORSALLY and CROSSCholine acetyltransferase stainMAINSECTION

Midbrainmedial lemniscussuperior cerebellar pedunclered nucleusCN IIIPeriaqueductal gray- Visceral coordination center for response to pain and other stress- Plays a role in central modification of pain- Target = nucleus raphe magnus (which in turn projects to dorsal horn)- Stimulation evokes fight/flight, quiescence, freezing, avoidance

Superior colliculus- Visual-motor reflex center

Inferior colliculus - Auditory relay

Superior cerebellar peduncle- Ascending fibers run ventrally into midbrain, cross, and run around red nucleus on their way to the thalamus

Cerebral peduncle- 1/3 corticospinal fibers, 2/3 corticopontine fibers

cerebral pedunclesuperior [inferior is caudal] colliculusperiaqueductal grayMAINSECTION

Brainstem SyndromesMedial MedullaryLateral MedullaryMedial Inferior PontineLateral Inferior PontineMedial Mid-PontineLateral Mid-PontineMedial Superior PontineLateral Superior PontineTegmentalVentralMAIN

Medial Medullary SyndromeARTERY: anterior spinal arteryLoss of vestibuloocular reflex*Tongue paralysisLoss of fine touch (contralateral)Cerebellar ataxiaLimb paralysis (contralateral)CN XII nucleusmedial longitudinal fasciculusmedial lemniscusinferior olivary fiberspyramidsMAINSECTION* VOR might be preserved because this is below the level of the vestibular nuclei

Lateral Medullary SyndromeARTERY: posterior inferior cerebellar artery (PICA)Loss of facial pain/temp sensation (ipsilateral)Hoarseness, difficulty swallowingHorners syndrome, ipsilateral loss of sweatingCerebellar ataxiaLoss of body pain/temp sensation (contralateral)nucleus ambiguusCN V spinal nucleusdescending symapthetic tractdorsal spinocerebellar tractspinothalamic tractMAINSECTION

Medial Inferior Pontine SyndromeARTERY: paramedian branches of the basilar arteryLoss of vestibuloocular reflexLoss of lateral rectus (ipsilateral)Loss of fine touch (contralateral)Cerebellar ataxiaLimb paralysis (contralateral)CN VI nucleusmedial longitudinal fasciculusmedial lemniscuspontine fiberscorticospinal tractMAINSECTION

Lateral Inferior Pontine SyndromeARTERY: anterior inferior cerebellar artery (AICA)Loss of facial pain/temp sensation (ipsilateral)Loss of body pain/temp sensation (contralateral)Hearing deficit (ipsilateral), vertigoFacial paralysis (ipsilateral)spinothalamic tractCN V spinal nucleusCN VIIICN VIIMAINSECTION

Medial Mid-Pontine SyndromeARTERY: paramedian branches of the basilar arteryLimb paralysis (contralateral)Facial paralysisCerebellar ataxiacorticobulbar tractcorticospinal tractcorticopontine/ pontocerebellar fibersMAINSECTION

Lateral Mid-Pontine SyndromeARTERY: circumferential branches of the basilar arteryWeakened masticationLoss of facial sensation (ipsilateral)No deficit reportedCN V main sensory nucleusCN V motor nucleuslateral lemniscusMAINSECTION

Medial Superior Pontine SyndromeARTERY: paramedian branches of the upper basilar arteryLoss of vestibuloocular reflexSoft palate temorLoss of fine touch (contralateral)Limb paralysis (contralateral)Cerebellar ataxiacentral tegmental bundlemedial longitudinal fasciculusmedial lemniscuscorticospinal tractpontocerebellar fibersMAINSECTION

Lateral Superior Pontine SyndromeARTERY: superior cerebellar arteryCerebellar ataxiaLoss of body pain/temp sensation (contralateral)Loss of fine touch (contralateral)spinothalamic tractsuperior cerebellar pedunclemedial lemniscuspontocerebellar fibersMAINSECTION

Tegmental SyndromeARTERY: paramedian branches of the basilar a. / posterior cerebral a.Cerebellar ataxiaLoss of fine touch to body and face (contralateral)No deficit reportedLoss of pupil constriction; lateral strabismusmedial lemniscussuperior cerebellar pedunclered nucleusCN IIIMAINSECTION

Ventral SyndromeARTERY: paramedian branches of the basilar a. / posterior cerebral a.Paralysis (contralateral)Loss of pupil constriction; lateral strabismuscerebral peduncleCN IIIMAINSECTION

SomatosensoryAscending Somatic PathwaysFine TouchPain/TemperatureProprioceptionLesionsPeripheralSpinal CordForebrainPeripheral ReceptorsSomatosensory CortexSomatosensory Plasticity

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Lesions - PeripheralMAINSECTION

Lesion locationSensory lossDistributionPeripheral nerveAll sensationDistribution of the nervePeripheral neuropathyLarge myelinated fibers firstBilateral, stocking-gloveSingle dorsal rootNoneSeveral dorsal rootsAllIpsilateral dermatomal (fine touch less affected than pain/temp)

Lesions - Spinal CordMAINSECTION

Lesion locationSensory lossDistributionCentral cord, earlyPain/tempBilateral, at level of lesionDorsal columnFine touch, positionIpsilateral, from lesion on downAnterolateral columnPain/tempContralateral, from lesion on downHemi-transection of cordFine touch, positionPain/tempIpsilateral, lesion on downContralat., lesion on downComplete cord transectionAll sensationLesion on down

Lesions - ForebrainMAINSECTION

Lesion locationSensory lossDistributionThalamusAll sensationContralateral (peri-oral facial sparing from ipsi fibers)CortexVaries by location of lesionContralateral

Peripheral ReceptorsMerkels diskMeissners corpusclePacinian corpuscleRuffini endingDermisEpidermisClick on a receptor:free nerve endingMAINSECTION

Merkels DiskDiscriminative Touch MechanoreceptorLocation:EpidermisSpecificity:Steady skin indentation form, textureDynamics:Slow-adaptingSpatial Range:Small receptive field (3-4 mm fingers, 30-40 cm trunk)2-point discrimination threshold = 1 mm fingers, 10 cm trunkConduction:A fiber 25 m/sMAINSECTIONRECEPTORS

Location:DermisSpecificity:Flutter; contact and movementDynamics:Fast-adaptingSpatial Range:Small receptive field (3-4 mm fingers, 30-40 cm trunk)2-point discrimination threshold = 1 mm fingers, 10 cm trunkConduction:A fiber 25 m/sMeissners CorpuscleDiscriminative Touch MechanoreceptorMAINSECTIONRECEPTORS

Location:Subcutaneous tissueSpecificity:Non-localized vibrationDynamics:Fast-adaptingSpatial Range:Large receptive fieldConduction:A fiber 25 m/sPacinian CorpuscleDiscriminative Touch MechanoreceptorMAINSECTIONRECEPTORS

Location:DermisSpecificity:Low frequency stimulationDynamics:Slow-adaptingSpatial Range:Large receptive fieldConduction:A fiber 25 m/sRuffini EndingDiscriminative Touch MechanoreceptorMAINSECTIONRECEPTORS

Free Nerve EndingPain/Temperature ReceptorMAINSECTIONRECEPTORS

ACSpecificityCold or fast painWarmth or slow painConduction25 m/s (myelinated)

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleS2M1Click on an area:Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:S1 Area 3aInput from thalamic shell (muscles, joints, deep mechanoreceptors)RFs similar to peripheryS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:S1 Area 3bInput from thalamic core (VPM/VPL - cutaneous)Each column within 3b is specific for one type of cutaneous receptorSmallest RFsS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:S1 Area 1Input from 3b and thalamic core (cutaneous)Large, complex RFs combine info from multiple receptor typesSensitive to motion, direction, orientationPrimarily tactile infoLESION trouble describing textureS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:S1 Area 2Input from 3a, 3b and thalamic core (cutaneous) + shell (muscle)Large, complex RFsCombines tactile and muscle infoLESION poor stereognosis, cant pick up small objects or maneuver hand through tight placesS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleS2M1Click on an area:S2Input from S1 and thalamusTwo complete mapsComplex RFs with influence of behavioral stateCollosal connections:Bilateral RFsInterhemispheric transfer of learned infoLESION problems with tactile discrimination, interhemispheric transfer of learned infoClick here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:Area 5Input from area 2 (S1)Cutaneous plus movementVery complex RFs: Multi-joint, multi-limbResponds differently to active and passive movementS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory Cortex43a3b1257lateral sulcuscentral sulcuspostcentral gyrusintraparietal sulcusposteriorparietal lobulecentralsulcuspostcentral gyrus S1intraparietalsulcusposteriorparietal lobuleM1Click on an area:Area 7High order visual areaActivity reflects spatial properties of visual stimuliLarge RFs, prominent effects of behavioral relevanceS2Click here for S1 topographyClick here for S1 histologyMAINSECTION

Somatosensory TopographyFace lies near fingers, not neck and head

Area devoted to each body part reflects the density of sensory innervation

Extremely distorted

All areas of S1 (3a, 3b, 1, 2) have complete maps

S2 has two complete mapsMAINSECTION

Somatosensory Cortexprecentral gyrusMOTORpostcentral gyrusSENSORYIIIIIIIV small granule cellsVVIMAINSECTION

Somatosensory PlasticityFinger amputated corresponding cortical areas are taken over by adjacent finger representations

Limb amputated (1) smaller phantom limb is perceived; (2) tactile acuity on stump increases, and its stimulation results in sensation on the phantom limbPossibly due to the stump taking over cortical territory

Better recovery if nerve is crushed rather than severed/reattachedRegenerating axons might follow their Schwann cell tubes

Plasticity does not require damageMAINSECTION

PainTypes of PainNociceptiveInflammatoryNeuropathicCentral Pain ModulationSensitizationPeripheralCentral

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Nociceptive PainTISSUEINJURYACTIVATENOCICEPTORSTypes of NociceptorsMAINSECTION

Inflammatory PainINSULTINFLAMMATORYMEDIATORS

NOCICEPTORACTIVATIONMAINSECTION

Neuropathic PainREPETITIVE STRESSINJURY (TO NERVES)LESIONPAINMAINSECTION

Types of NociceptorsLocation: Everywhere but the CNSNeurotransmitters:All are excitatory glutamatergic (AMPA, NMDA, kainate, metabotropic)Some express peptide NTs like substance P, CGRP, NPYMAINSECTION

NociceptorResponds toFiber typeMyelinationConductionType of painChannel types(Transduction)ThermalExtreme temperature (>45oC or < 5oC)A Light myelin5-30 m/sSharp, stinging, well localizedTRP (Transient Receptor Potential)MechanicalIntense pressureALight myelin5-30 m/sSharp, stinging, well localizedDEG/ENaC (ASIC - Acid Sensing Ion Channel)Maybe TRPPolymodalExtreme temperatureIntense pressureNoxious chemicalsC fibersNo myelin1 m/sDull aching or burning, prolonged, poorly localizedDEG/ENaC (ASIC)

Central Pain ModulationNRM projectionterminusdorsal horn neuron(ascending pain afferent)NOTE:Dorsal horn neuron also receives descending pain-facilitation inputs.Serotonin has other indirect effects, involving opiate receptors and enkephalins.CLICKMAINSECTION

Sensitization - PeripheralInjurymast celldorsal horndorsal root ganglionnociceptor /peripheral endingMAINSECTIONCLICK

Sensitization - Centraldorsal hornnociceptorterminusdorsal hornneuronion channelsMAINSECTIONCLICK

MotorMotor PathwaysDeficits/LesionsMotor CortexReflexesPostureCN VIIBasal GangliaCerebellum

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Motor PathwaysMotor input to CN nuclei: Corticobulbar tract

Lateral descending motor pathwayCorticospinal tractControl of voluntary limb movements (distal body parts)

Medial descending motor pathwayVestibulospinal, tectospinal, reticulospinal tractsControl of postural movements (proximal body parts)

Other: Rubrospinal tract is involved in voluntary limb movementsMAINSECTION

Motor DeficitsDamage to the descending pathwaysMAINSECTION

Negative DeficitPositive DeficitSevering amotor nerveWeakness or paralysisFibrillation (spontaneous firing of single muscle fibers)Disease ofmotor neuronsWeakness or paralysisFasciculation (spontaneous firing of an axon twitch of all fibers in the motor unit)

Damage to Descending PathwaysEffect on stretch reflexesAutonomous and overactive (exaggerated)Claspknife reactionPassively extend limb spindle stretch-induced contraction (resistance) activate GTO sudden relaxationClonusRhythmic contraction-relaxation tremorOccurs when you suddenly stretch a muscle and hold at a longer lengthDue to cyclic alternations of stretch reflex, GTO, and Renshaw inhibition

Effect on pain-sensing reflexesFlexor spasmsExtreme maintained flexion of leg at foot, knee, and hipDue to hyperactive pain reflexesBabinski responseBig toe moves up when sole of foot is sharply stimulatedNormal in infantsIn adults, is the first sign of hyperactive pain reflexesMAINSECTION

Cortical Regionsprefrontal cortexPMASMAM1 (Area 4)central sulcusS1Area 6Area 5Area 7posterior parietal cortexPrimary motor cortexPMA = premotor areaSMA = supplementary motor areaSomatosensory cortical areasSecondary motor cortical areasClick:MAINSECTION

Primary Motor Cortex (M1)Motor cortical neurons fire to cause voluntary movement (via corticospinal/ corticobulbar pathways)Lesions in this pathway (prior to synapse in the spinal cord ventral horn) result in upper motor neuron deficitsImpaired movement at individual jointsWeaknessIncreased sensitivity and magnitude of spinal reflexes (stretch & nociceptive)Irritation in the cortex can cause seizuresFocal (face or arm or leg) or marching (face arm leg)

Columnar organizationDifferent neurons code for muscle force, joint position, movement direction

Specialty: Moving single digits must actively hold other digits still (digits 3, 4, 5 have individual tendons but just one muscle)

Access M1 by conscious thought over pathways from frontal and parietal cortexM1 topographyM1 histologyMAINSECTIONCORTEX

Motor Cortex TopographyDistal body parts have greater representation than proximal body parts

Map is over-detailed in reality, cortical lesions affect entire body regions (face, arm, leg) and not smaller parts

Corticospinal neurons are the largest in the leg area

M2 map is more diffuse than M1MAINSECTIONCORTEX

Motor Cortexprecentral gyrusMOTORpostcentral gyrusSENSORYIIIIIIVVIcontains large pyramidal Betz cellsGigantocellular pyramidal cells of Betz (layer V)Cells of origin of the corticospinal fibersProvide much of the direct projection onto MNsPresent in M1 onlyMAINSECTIONCORTEX

Secondary Motor Cortical AreasHigh level planning of movements

Thinking about movements without actually making them

Arm the transcortical reflexes click here for more infoSMA, PMC, PFCMAINSECTIONCORTEX

ReflexesMuscle SpindleGolgi Tendon OrganReciprocal InhibitionCrossed Extension Flexor ReflexLocomotionTranscortical ReflexMAINSECTION

Muscle Spindlemuscle spindlequadricepsbiceps tendon2) Spindle stimulated (1a, II)3) -MN fires muscle contracts-MN fires spindle fibers contract* click on label for detailschain fiberbag fiber4) Renshaw cell inhibits -MNRenshaw cell stimulatedMuscle spindle is involved in(click here)MAINSECTIONREFLEXESCLICK

Muscle Spindlemuscle spindlequadricepsbiceps tendon2) Spindle stimulated (1a, II)3) -MN fires muscle contracts-MN fires spindle fibers contract* click on label for detailschain fiberbag fiber4) Renshaw cell inhibits -MNRenshaw cell stimulatedMuscle spindle is involved in(click here)MAINSECTIONREFLEXESMuscle spindle is involved inMaintaining constant muscle length (feedback servo)ClonusClaspknife reflexSegmental stretch reflexTranscortical reflexConscious sensation of limb position and balanceAutonomic control of balance

Muscle Spindlemuscle spindlequadricepsbiceps tendon2) Spindle stimulated (1a, II)3) -MN fires muscle contracts-MN fires spindle fibers contract* click on label for detailschain fiberbag fiber4) Renshaw cell inhibits -MNRenshaw cell stimulatedMuscle spindle is involved in(click here)MAINSECTIONREFLEXES1a = primary (annulospiral) afferent ending- Sensitive to the rate of muscle stretch- Fast- Sensitive to vibration (recall the proprioception lab)- Servocontrol the viscosity of contraction

II = secondary (flower spray) afferent ending Sensitive to the length of muscle stretch Slower than Ia uses excitatory interneuron1aII

Muscle Spindlemuscle spindlequadricepsbiceps tendon2) Spindle stimulated (1a, II)3) -MN fires muscle contracts-MN fires spindle fibers contract* click on label for detailschain fiberbag fiber4) Renshaw cell inhibits -MNRenshaw cell stimulatedMuscle spindle is involved in(click here)MAINSECTIONREFLEXES1-MN innervates nuclear bag fibers- Dynamic- Increase spindle velocity sensitivity

2-MN innervates nuclear chain fibers- Static- Increase spindle length sensitivity

Muscle Spindlemuscle spindlequadricepsbiceps tendon2) Spindle stimulated (1a, II)3) -MN fires muscle contracts-MN fires spindle fibers contract* click on label for detailschain fiberbag fiber4) Renshaw cell inhibits -MNRenshaw cell stimulatedMuscle spindle is involved in(click here)MAINSECTIONREFLEXES-MN innervates skeletal muscle

One MN activates all muscle fibers in the motor unit to produce a twitch

Force is generated by- Maintained firing of single motor units (rate encoding)- Recruitment of additional motor units small ones are recruited first

Force is smoothed out by fusion of many twitches

-MN activates Renshaw cell Renshaw cell inhibits -MN limits maximal rates of MN firing

Nerve-muscle endplate

Golgi Tendon Organ (GTO)-MN -MN fromspinalcord1) High muscle tension (force)2) GTO stimulated (Ib)3) Interneuron inhibits -MN 4) -MN decreases firing 5) Decreased muscle tensionRoles of the GTO:Protect against hurtful muscle stretchServo-control force (e.g., combat weakness due to muscle fatigue)GTO is involved in:ClonusClaspknife reflexGTOMAINSECTIONREFLEXESCLICK

Reciprocal Inhibitionagonist muscle(flexor)muscle spindleantagonist muscle(extensor)INHIBITEDACTIVATEDMAINSECTIONREFLEXESCLICK

Crossed Extension Flexor ReflexInvolves the spinal cord bilaterallyFlexion of one limb evokes extension of the opposite limb

ApplicationsSpinal withdrawal reflexHurtful stimulus withdraw stimulated limb + extend opposite limbLocomotionBrainstem activity oscillation of leg flexion and extensionMAINSECTIONREFLEXES

Locomotion Modulationmotor cortexmidbrain locomotorregion (MLR)corticospinal tractsreticulospinal tractInitiate locomotory activity in spinal cord circuitsModify locomotory activity for voluntary corrections of gait (obstacle avoidance)MAINSECTIONREFLEXES

Transcortical ReflexesSMApyramidal tract neuron (PTN)1) SMA sets PTN by low-level firing - Conscious intent (willing the reflex to occur)2) Muscle is stretched (or skin is touched)3) Muscle spindle sends 1a afferent to thalamus PTN4) PTN fires and stimulates MNs in the ventral horn5) -MN and -MN fire6) Muscle contracts length is restoredMAINSECTIONREFLEXESCLICK

Vestibulospinal reflexes can act ALONE if you tilt your head up/down without extending/flexing your neck.Tonic neck reflexes can act ALONE if you extend/flex your neck without tilting your head up/down.

If you combine head tilt with neck flexion/extension, either- the tonic neck reflex will CANCEL the vestibulospinal reflex, or- the tonic neck reflex will ADD to the vestibulospinal reflex.Normal Postural ReflexesHead upHead normalHead downNeck extendedNeck normalNeck flexedVSR aloneTNR aloneVSR TNRVSR + TNRVSR = vestibulospinal reflexTNR = tonic neck reflexThe TNR involves

the reticulospinal pathway for somatosensory input.

the tectospinal pathway for visual input.

To maintain balance, you must have two of the following:

Somatosensory inputVisual inputVestibular inputTips for learning this chartMAINSECTIONAbnormal Posture

Vestibulospinal reflexes can act ALONE if you tilt your head up/down without extending/flexing your neck.Tonic neck reflexes can act ALONE if you extend/flex your neck without tilting your head up/down.

If you combine head tilt with neck flexion/extension, either- the tonic neck reflex will CANCEL the vestibulospinal reflex, or- the tonic neck reflex will ADD to the vestibulospinal reflex.Normal Postural ReflexesHead upHead normalHead downNeck extendedNeck normalNeck flexedVSR aloneTNR aloneVSR TNRVSR + TNRVSR = vestibulospinal reflexTNR = tonic neck reflexThe TNR involves

the reticulospinal pathway for somatosensory input.

the tectospinal pathway for visual input.

To maintain balance, you must have two of the following:

Somatosensory inputVisual inputVestibular inputKnow that for VSR alone (head movement only), head up forelimbs flex & hindlimbs extend (and opposite if head is down).Know that for TNR alone (neck movement only), neck extended forelimbs extend & hindlimbs flex (and opposite if neck is flexed).Combining a head movement and neck movement: If the limb positions resulting from VSR and TNR agree, then the reflexes add (limb hyper-extension/flexion).If the limb positions resulting from VSR and TNR disagree, then the reflexes cancel (no limb movement).MAINSECTION

Abnormal PostureWhen the head is passively turned to one side, the looked-at limbs will extend and the others will flex.

This is normal in infants but is a sign of corticospinal lesion in adults.Extension of all four limbs, extension of neck, slight intorsion of legsUsed normally when riding a bikeHyperactive vestibulospinal reflexes no tonic neck reflexCaused by a lesion of the upper pons or midbrain (medial descending motor pathways)Damage the tectospinal and corticospinal pathwaysVestibulospinal pathway remains intactUsually more serious than internal capsule injury (decorticate posture)Flexion of upper limb, extension of lower limb, slight intorsion of legsHyperactive vestibulo-spinal AND tonic neck reflexes (see right)Caused by a lesion of the internal capsule (corticospinal pathway)DECORTICATEDECEREBRATEMAINSECTION

CN VII Innervationto lower facial muscles (left)to upper facial muscles (left)RLCN VII nucleiClick on a lesion site (circled in purple)NORMALMAINSECTION

CN VII Innervationto lower facial muscles (left)to upper facial muscles (left)RLCN VII nucleiXLesion of left peripheral CN VII- Left UPPER and LOWER facial weakness- Cannot wrinkle forehead, brow droops, nasolabial fold diminished, mouth droopsMAINSECTION

CN VII Innervationto lower facial muscles (left)to upper facial muscles (left)RLCN VII nucleiXLesion of right motor cortex, internal capsule, midbrain, or upper pons Left LOWER facial weakness only Upper facial muscles still have innervation from the left corticobulbar tract- Nasolabial fold diminished, mouth droopsMAINSECTION

Basal GangliaCaudatePutamenNucleus accumbensGlobus pallidus, externa (GPe)Globus pallidus, interna (GPi)Amydala (part of lymbic system)Subthalamic nucleus (STN)Substantia nigra click here- pars reticulata (SNpr)- pars compacta (SNpc)Lenticular nucleus = Globus pallidus + PutamenStriatum = Globus pallidus + Putamen + CaudateROSTRALCAUDALConnectionsDiseasesSelection-BrakeNTsMAINSECTION

Substantia Nigra - HistologySNpcdopaminergicSNprGABAergicMAINSECTIONBG

Basal Ganglia NeurotransmittersDopamineGABAEnkephalinSubstance PGlutamateACh

NOT norepinephrineMAINSECTIONBG

Basal Ganglia ConnectionsSC = superior colliculusPPPA = peri-pedunculo-pontine areaVA/VL = ventroanterior/ventrolateral nuclei of thalamusThe caudate and putamen receive most of the basal gangia input from the cerebral cortex.The caudate/putamen send some info to the SNpc, which sends info back.But most of the caudate/putamen output goes to the GP and SNpr. The SNpr projects outside the basal ganglia to control head/eye movements.The GP (GPi, specifically) sends most of the inhibitory input to the thalamus.GPi also projects to the PPPA, probably for postural control.The globus pallidus (GPe and GPi) are both in communication with the STN.= excitatory (Glu)= inhibitory (GABA)= mixed (DA)= unknownShow selection-brake mechanismMAINSECTIONBGCLICK

Basal Ganglia Connectionscerebral cortexSC = superior colliculusPPPA = peri-pedunculo-pontine areaVA/VL = ventroanterior/ventrolateral nuclei of thalamus= excitatory (Glu)= inhibitory (GABA)= mixed (DA)= unknownSNpcGPeGPiSNprSTNVA/VLPPPASCbrainstem/spinal cordcaudate / putamenPerson wants to make a voluntary movementPremotor/motor cortex excite STNSTN excites GPiGPi inhibits MPGsDIRECT path from caudate/putamen to GPi INHIBITS GPiINDIRECT path from caudate/putamen GPe GPi DISINHIBITS GPi Release the MPGs (those desired for the movement) Shut down the MPGs (those interfering with the movement)= excitatory= inhibitoryMAINSECTIONBGCLICK

Selection-Brake HypothesisBasal ganglia outputs are inhibitory to the thalamus and motor pattern generators (MPGs)

When a movement is madethe BG outputs to the desired MPGs decrease their firing rate (take off the brake).the BG outputs to interfering MPGs increase their firing rate (put on the brake).Click here for the selection brake mechanismMAINSECTIONBG

Basal Ganglia DiseasesDamage to BG output cells removes tonic inhibition from all motor pattern generators (MPGs)Results in sustained contraction in all muscles, agonist and antagonistMPGs operate independently and intermittently, resulting in spontaneous involuntary movements

Bradykinesia: slow movement

Akinesia: lack of movementGeneral PathophysiologyParkinsons DiseaseHuntingtons DiseaseMAINSECTIONBG

Parkinsons DiseaseCaused by degeneration of the SNpc (dopaminergic)SNpc modulates putamen and caudatePutamen/caudate can no longer focus the GPi output

SymptomsRigidity, bradykinesia, akinesia, pill-rolling tremorCan be mimicked by taking dopamine receptor blockers

TreatmentGive oral L-dopa, a precursor to dopamineToo much L-dopa develop chorea/hemiballismus (involuntary, gesture/dance-like movements)Ablate or electrically stimulate the STNThis causes chorea in normal subjects, but restores normal function to Parkinsons patientsMAINSECTIONBG

Huntingtons DiseaseCaused by damage of the caudate/putamen or STNResults in excessive activity in the caudate/putamen

SymptomsChorea, athetosis, hemiballismusWrithing, purposeful-looking but involuntary movementsHemiballismus is specifically caused by STN lesion

TreatmentDrugs that block dopamine receptors in the putamenIs worsened by L-dopa or dopamine agonists (unlike in Parkinsons)MAINSECTIONBG

CerebellumFoliumCortical CellsDeep NucleiConnectionsMAINSECTION

Cerebellar Foliummolecular layerPurkinje cell layergranule cell layerwhite matterClick here to overlay cell types/connectionsMAINSECTIONCB

Cerebellar FoliumPurkinje cellGranule cellClimbing fiberMossy fiberparallel fiberterminal(synapse)dendriteterminaldendritesynapseaxonto the deep nucleiClick on a cell type:Stellate cellBasket cellGolgi cellNot shown (can click):MAINSECTIONCB

Purkinje CellOne Purkinje cell receives input fromOne climbing fiberMany parallel fibers (up to a million)Inter-Purkinje cell connections via parallel fibers allow motor coordination to occur

Projects to and inhibits the deep nuclear cellsPurkinje cell bodymolecular layergranule cell layerPurkinje cell dendriteMAINSECTIONCB

Climbing FiberCell bodies reside in the inferior olive

Projects to the Purkinje cell layer, where one climbing fiber synapses with one Purkinje cellExcitatoryClimbing fiber input weakens the excitatory effect of parallel fibers on the Purkinje cell

Fire at high rates when learning movement, low rates during learned movementmolecular layergranule cell layerclimbing fiberMAINSECTIONCB

Granule CellReceives input from mossy fibers in the granule cell layerExtends claws to grab the mossy fiber terminus

Projects to molecular layer, where the fiber then runs parallel to the folia surfaceThese parallel fibers synapse on and excite Purkinje cell dendritesOne synapse per Purkinje cellOne parallel fiber connects many Purkinje cellsThe coincidence of parallel and climbing fiber excitation of the Purkinje cell results in learning related to coordinationgranule cellparallel fibermolecular layergranule cell layerMAINSECTIONCB

Mossy FiberOriginates in theSpinocerebellar pathwayAscending (from spinal cord)Fibers do not crossEnters cerebellum through the inferior cerebellar pedunclePonsDescending (from cerebral cortex)These fibers must cross in the cerebral peduncles (corticopontine fibers)Enter cerebellum through the middle cerebellar peduncle

Projects to the granule cell layer, where it synapse on the claws of the granule cellsExcitatorymossy fibersmolecular layergranule cell layerMAINSECTIONCB

Inhibitory InterneuronsStellate cellMolecular layer

Basket cellCell body in molecular layerProjections wrap around Purkinje cell

Golgi cellGranule cell layerbasket cellPurkinje cell bodyMAINSECTIONCB

Cerebellar Deep NucleiReceive inhibitory input from Purkinje cortical cellsProject to brainstem and thalamus click hereEach nucleus has a separate body mapHelp initiate movement click hereFastigial (medial) nucleusDentate (lateral) nucleusGlobose/emboliform (intermediate) nucleiClick on a nucleus:MAINSECTIONCB

Deep Nuclei and MovementDeep nuclei probably help initiate movement because

their stimulation results in movement.their damage delays movement initiation.they send excitatory projections to their targets.MAINSECTIONCB

Nuclear Functions/LesionsMovements involving multiple joints are more impaired than those involving a single joint.Patients may try to compensate by moving more slowly or moving one joint at a time.Lesions prevent several types of motor learning.MAINSECTIONCB

NucleusInputFunctionLesion results inFastigial (medial)VestibularControl upright stance against gravityFalls to the side of the lesionGlobose/ emboliform (interposed)Cerebral cortex Spinal cordBalance agonist and antagonist muscles at a single jointIpsilateral action tremor during voluntary movements (e.g. reaching)Dentate (lateral)Cerebral CortexCombined digit movementsArm/leg reaching to a visual targetIncoordination of digitsOvershoot targets in reaching with arm/leg

Cerebellar Connectionsventrolateral thalamusred nucleusvestibular nucleireticular formationAll cerebellar projections are excitatoryMAINSECTIONCB

Autonomic Nervous SystemEfferents/AfferentsCircumventricular OrgansFunctionsBaroreceptorRespirationMicturitionPeriaqueductal Gray (PAG)MAIN

Viscero-Motor Efferents / Visceral AfferentsSympathetic EfferentsOutput arises from the intermediolateral (IML) cell column from T1 to L2Relay through sympathetic trunk

Parasympathetic EfferentsSacral outputFrom cells similar to the IML in the sacral cordRelays through ganglion cells in the pelvic plexusCranial outputRuns in CN III, CN VII, CN IX, CN XArises in nuclei associated with the CNs

Visceral AfferentsReturn to the CNS with sympathetic & parasympathetic efferent fibersCell bodies are in dorsal root or CN gangliaSympathetic afferents: Pain (synapse on cells of spinothalamic tract)Parasympathetic afferents: State of the visceraCN VII, CN IX, CN XMAINSECTION

CN III ParasympatheticsEdinger-Westphal nucleusCN III nucleusCN IIIciliary ganglionto pupilloconstrictor and ciliary musclesPupillary Constriction and AccommodationMAINSECTION

CN VII and IX ParasympatheticsViscero-motorParasympathetic fibers in CN VII and IX arise from salvatory/lacrimal nucleiScattered cells in the pons and upper medullaRelay through submandibular, pterygopalatine, otic gangliaResponsible for secretion from salvatory glands, lacrimal gland, and other glands in mouth and nasal cavity

Visceral afferentsSynapse in the nucleus of the solitary tractCN VII: Taste infoCN IX: Info from carotid body/sinus, pharynxMAINSECTION

CN X Parasympatheticsdorsal nucleus of CN Xnucleus of the solitary tractnucleus ambiguus= secretomotor efferents= vasomotor efferents= visceral afferentsGUTHEARTPHARYNX/ LARYNXMAINSECTION

Circumventricular Organsarea postremadorsal nucleus of CN Xnucleus of the solitary tractsolitary tractCN XII nucleusArea postrema, subfornical organ, organum vasculosum of the lamina terminalis (OVLT)Small areas around the 3rd and 4th ventriclesLACK a blood brain barrierChemosensitive neurons detect circulating molecules/ hormones (AII, insulin, vasopressin)MAINSECTION

Circumventricular Organsarea postremadorsal nucleus of CN Xnucleus of the solitary tractsolitary tractCN XII nucleusArea postrema, subfornical organ, organum vasculosum of the lamina terminalis (OVLT)Small areas around the 3rd and 4th ventriclesLACK a blood brain barrierChemosensitive neurons detect circulating molecules/ hormones (AII, insulin, vasopressin)Area postrema- In caudal part of 4th ventricle- Connects to NTS and other autonomic centers- Acts as a vomiting center

OVLT- Sensitive to circulating Na+ levels Helps control electrolyte concentration via posterior pituitary hormones

MAINSECTION

Baroreceptor Reflexnucleus of the solitary tractnucleus ambiguuscaudal ventrolateral medullarostral ventrolateral medullaintermedio-lateral columnperipheral arteriolesaortic arch baroreceptorscarotid sinus baroreceptorstonic= inhibitory= excitatory= parasympathetic= sympatheticMAINSECTION

RespirationForebrainParabrachial nucleusLung stretch receptorsCarotid body chemoreceptorsIntrinsic chemoreceptorsNucleus of the solitary tractRostral inspiratoryExcitatoryCaudal expiratoryExcitatoryBotzinger complexReciprocal inhibitionPhrenic motorneuronsExt. intercostalsInt. intercostal motorneuronsAbdominal musclesVentral respiratory pre-motor cells= excitatory= inhibitoryPre-Botzinger cellsRespiratory rhythmVENTROLATERALMEDULLAMAINSECTION

MicturitionHypothalamus, PAGpontine micturition center (parabrahial region)sacral spinal cordbladder= afferent= efferentShort loop reflexLong loop reflexMAINSECTION

MicturitionHypothalamus, PAGpontine micturition center (parabrahial region)sacral spinal cordbladder= afferent= efferentShort loop reflex- Bladder stretch triggers bladder contraction- Used by infantsMAINSECTION

MicturitionHypothalamus, PAGpontine micturition center (parabrahial region)sacral spinal cordbladder= afferent= efferentLong loop reflex- Hypothalamic/PAG input plus bladder stretch info control bladder contraction- Used by adults for better control of micturition- GABAergic neurons play a roleMAINSECTION

Periaqueductal Gray (PAG)Integrates several autonomic reflexes

Receives visceral afferent projections (like the parabrachial nuclei)

Outputs: hypothalamus, amygdala, other forebrain areasPAGMAINSECTION

PAG region stimulatedEvokesIn response toLateralFight or flightSuperficial (escapable) painVentrolateralQuiescenceDeep (inescapable) pain

Eye Movements / Ocular DominanceOcular Dominance ColumnsMAIN

GoalEye movementFunctionStabilize the eye when the head moves (reflexive)Vestibulo-ocularUse vestibular input to hold images stable on retina during brief/fast head movementOptokineticUse visual input to hold images stable on retina during sustained/slow head movementKeep the fovea on a visual target (volitional control)SaccadeBring new objects of interest into the foveaSmooth pursuitHold image of a moving target on the foveaVergenceAdjust the eyes for viewing distances in depth (converge for near, diverge for far)

Vestibulo-Ocular Reflex (VOR)Secondary pathway (visual cortex cerebellar flocculus)semicircular canalvestibular nuclear complexmotor nuclei to eye muscleseye musclesIf the head moves left quickly, VOR causes the eyes to move right.But the VOR can get out of tune if it operates alone. Therefore, a secondary pathway (long latency, multisynaptic, involving the visual system and cerebellum) synapses on ocular motorneurons and adjusts the gain of the reflex.The VOR depends on the stimulation of kinocilium in the vestibular labyrinth.MAINSECTIONCLICK

Optokinetic ReflexSenses motion of the visual background (involves the extrastriate cortex)

NystagmusSlow phase: Compensatory tracking movements (smooth pursuit)Fast phase: Anticipatory fast movement to reposition eyes after they reach the edge of the orbit (saccade)Eye position (degrees)Time (sec)MAINSECTION

Ocular Dominance Columns (ODCs)Features of ODCsLocated in V1Develop prenatallyVisual input to each ODC is monocular (by looking out of one eye, you drive just one set of ODCs)

Development of binocular visionRequires visual experience and development of inter-ODC connectionsOccurs during the critical period (60-90 days postnatally)

Conditions that result in binocular vision impairmentStrabismus: Misaligned eyesIf subject becomes accustomed to using just one eye at a time, left and right ODCs will never be co-stimulated and no inter-ODC connections will developAnisometropia: One eye more nearsighted than the other, due to unilateral amblyopia (poor visual acuity)There is more metabolic activity in the non-amblyopic columnsMAINSECTION

Periventricular nucleusLateral hypothalamic areaDorsomedial nucleusSupraoptic nucleusVentromedial nucleusArcuate nucleusfornixmedian eminencePVZMHALHAZONESTRUCTURE(S)Paraventricular nucleus (not shown)OTHERPVZ = Periventricular zoneMHA = Medial hypothalamic zoneLHA = Lateral hypothalamic zoneHypothalamusSuprachiasmatic nucleus (not shown)Hypothalamic InputsHypothalamic OutputsAnterior PituitaryClick on a zone, nucleus, or buttonPosterior PituitaryPhysiological RegulationMAIN

HypothalamusPeriventricular nucleusLateral hypothalamic areaDorsomedial nucleusSupraoptic nucleusVentromedial nucleusArcuate nucleusPVZMHALHAZONESTRUCTURE(S)Paraventricular nucleus (not shown)OTHERPVZ = Periventricular zoneMHA = Medial hypothalamic zoneLHA = Lateral hypothalamic zoneSuprachiasmatic nucleus (not shown)fornixmedian eminenceHypothalamic InputsHypothalamic OutputsAnterior PituitaryPosterior PituitaryPhysiological RegulationPeriventricular zone- Thin area immediately around the 3rd ventricle Directly involved in control of endocrine function through the pituitary

Medial hypothalamic area- Receives limbic and other inputs- Extensive connections with other hypothalamic regions- Caudally, this region is occupied by the mammillary nuclei

Lateral hypothalamic area- Diffuse region of scattered cells and the medial forebrain bundle (connects to rostral limbic forebrain and to autonomic regions of brainstem and spinal cord)MAINSECTION

Hypothalamic Nucleifornixmedian eminencelateral hypothalamic areaventromedial nucleusfornixarcuate nucleusmedian eminenceparaventricular nucleusorexin cells?MAINSECTION

Hypothalamic Nucleifornixmedian eminencesupraoptic nucleusanterior hypotha-lamic areaanterior commissuresuprachiasmatic nucleusMAINSECTION

Hypothalamic Nucleifornixmedian eminencelateral hypothalamic areaventromedial nucleusarcuate nucleus (dopa-minergic cells)paraventricular nucleusoptic tractdorsomedial nucleusMAINSECTION

Inputs to HypothalamusMAINSECTION

TypeStructureCarries info aboutExtrinsicReticular formationTemperatureRetinaLight/dark cycle (to suprachiasmatic nucleus)Nucleus of the solitary tractParabrachial nucleusTaste, visceral sensationOlfactory cortexFood, sexual attractantsAmygdala, hippocampus, prefrontal cortex (limbic input)CognitionCircumventricular organsOsmolality of bloodPeptide hormones in blood (AII, atrial natiuretic factor)IntrinsicThermoreceptorsLocal blood temperatureOsmoreceptorsLocal CSF ionic strengthChemoreceptorsHormones (e.g., leptin, ghrelin)

Outputs from HypothalamusMAINSECTION

FromToEffectLateral hypothalamusParaventricular nucleusAutonomic nuclei in spinal cord, brainstem(PAG, parabrachial nuclei, nucleus of the solitary tract, dorsal vagal nucleus, ventrolateral medulla, IML)Control body temp (sweating, shivering, vasoconstriction)Releasing hormone neurons in periventricular zone (arcuate nucleus and part of the paraventricular nucleus)Median eminenceControl of anterior pituitary

Supraoptic and paraventricular nucleiPosterior pituitarySecrete ADH, oxytocinScattered large neuronsCerebral cortexLimbic structuresNot clear; presumably contribute to hypothalamic control of behavior

Anterior PituitaryCRHTRHGnRHGHRHSomatostatinDopamineACTHTSHLH/FSHGHGH/TSHMSHmedian eminenceperiventricular zone of the hypothalamus(arcuate nucleus and part of the paraven-tricular nucleus)hypothalamic releasing hormonescorresponding anterior pituitary hormonesHypothalamic cell axons terminate in the median eminence and secrete hormones into the fenestrated pituitary portal capillariesMAINSECTION

Posterior Pituitarysupraoptic nucleus / paraventricular nucleusPosterior pituitary hormones:- oxytocin- ADH (vasopressin)median eminenceHypothalamic cell axons terminate in the posterior pituitary and secrete hormones into the fenestrated pituitary capillariesMAINSECTION

The hypothalamus regulatesBody temperatureBody weightIonic balanceBlood pressure (chronic)Circadian rhythmReproductionResponse to stressMAINSECTION

Body Temperaturespinal cord

reticular formationintrinsic thermoreceptorsreleasing hormone neurons

anterior hypothalamus

TSH, GH, somatostatinlateral hypothalamus

autonomic nuclei

sweating, shivering, etc.cerebral cortex

behavior?inputsoutputs/effectsMAINSECTIONREG

Body Weightviscera (gut)food intake, gut distension

NTS / parabrachial nucleitonguetaste

NTSolfactory cortexsmellfat cells leptin(receptors in dorsomedial nucleus)gut ghrelinorexinsuppress food intake / increase metabolismpromote food intake / decrease metabolismpromote food intake / stabilize sleepautonomic nucleipituitaryinputsoutputs/effectsMAINSECTIONREG

Ionic Balancecircumventricular organsblood osmolality, peptide hormonesintrinsic osmorecptorsCSF tonicityvena cava / R atriumblood volume

NTSposterior pituitary

ADH

alter urine tonicity, Na+ and H2O intakeinputsoutputs/effectsMAINSECTIONREG

Blood Pressure (Chronic)baroreceptors

NTSangiotensin II

circumventricular organsautonomic nuclei

vasoconstrictioninputsoutputs/effectsposterior pituitary

ADH

vasoconstriction, anti-diuretic action on kidneyMAINSECTIONREG

Circadian Rhythmretinainputsoutputs/effectscouple the circadian rhythm to the light/dark cycleThe suprachiasmatic nucleus of the hypothalamus (and the surrounding region) sets the circadian rhythm.Input from the retina allows the cycle to be coupled to the light/dark cycle. suprachiasmatic nucleusMAINSECTIONREG

Reproductionolfactory systemgonadal steroidsinputsoutputs/effectsreproductionamygdala / hippocampusemotion, memoryMAINSECTIONREG

Response to Stressascending catecholamine systems

limbic systeminputsoutputs/effectsCRH

ACTH

glucosteroid release from adrenal cortex

change glucose metabolism and energy useGlucosteroids can inhibit the hypothalamus to terminate the stress response.Chronic glucocorticoids can cause neuronal and other damage, possibly contributing to post-traumatic stress disorder, depression, and other disorders.MAINSECTIONREG

Limbic Systemcingulate gyrus / cingulumamygdalafornixhippocampusparahippocampal gyrusdentate gyrusmammillary bodystria terminalisolfactory bulbanterior commissurehypothalamusorbital/medial prefrontal cortexNot shown: olfactory cortexMAIN

Amygdalacentral nucleusbasal nucleusaccessory basal nucleuslateral nucleusmedial nucleusPACPAC = periamygdaloid complexDorsal nucleiDeep nucleinucleus basalis of Meynertamydalaentorhinal cortexRoleInputs/OutputsMAINSECTION

Amygdalacentral nucleusbasal nucleusaccessory basal nucleuslateral nucleusmedial nucleusPACPAC = periamygdaloid complexDorsal nucleiDeep nucleinucleus basalis of Meynertamydalaentorhinal cortexDorsal nuclei- Receive projections from the deep nuclei- Send signals to the hypothalamus and brainstem (autonomic nuclei)

Deep nuclei- Collect input from the temporal, insular, and frontal cortices; the striatum; and the mediodorsal thalamus

Periamygdaloid complex (PAC)- Interconnected with the olfactory systemMAINSECTIONAMYG

Amygdalacentral nucleusbasal nucleusaccessory basal nucleuslateral nucleusmedial nucleusPACPAC = periamygdaloid complexDorsal nucleiDeep nucleinucleus basalis of Meynertamydalaentorhinal cortexNucleus basalis of Meynert- Neurotransmitters are ACh and GABA- Axons terminate in the posterior pituitary- Modulates the responsiveness of cortical neuronsMAINSECTIONAMYG

The amygdala is involved inMaking cortical cells more responsive to other synaptic inputsMost cells of the amygdaloid nuclei are cholinergicHelp activate (desynchronize) cortex during waking state

Fear conditioningModulate brainstem reflexes in response to emotional status

Recognizing fear in others

Depression (may show increased activity)

Kluver-Bucy SyndromeAssociated with temporal lobe ablationCannot recognize the significance of objects; loss of fear; failure to learnMAINSECTIONAMYG

Inputs/Outputsascending sensory systemvisual, olfactory, auditory, somatosensoryinputsoutputs/effectsautonomic cell groupslateral hypothalamus, PAG, parabrachial nucleus, NTS, dorsal nucleus of CN X, ventrolateral medulla

influence HR, BP, gut/bowel/respiratory/bladder function, etc.orbital/medial prefrontal cortex

determine whether sensory stimulus is rewarding or aversive; set mooddirect OR via mediodorsal thalamusthalamic relay nucleusprimary sensory cortexsecondary association cortexposterior intralaminar thalamic nucleiMAJORSHORTCUTThe shortcut afferent pathway produces your initial gut reaction to a potentially threatening situation, before the major pathway kicks in.feedbackOR via the ventromedial striatumAmygdalaMAINSECTIONAMYG

Olfactory Bulbolfactory nervesglomerular formationsmitral cellsgranule cellsMitral cellsPrincipal relay cellsDendrites extend to the glomerular formations and synapse with olfactory receptor neurons (reciprocal, dendritodentritic synapses)

Granule cellsDeepProcesses interact with mitral cell dendrites in the external plexiform layerGABAergicSuperficialSynapse with mitral cell dendritesGABA (most), dopamine, neuropeptides (enkephalin, substance P, neurotensin)

MAINSECTION

Olfactory Cortexprimary olfactory cortexolfactory tractputamennucleus accumbens /olfactory tuberclelateral striate arteriesAt the junction of frontal and temporal cortices

Axons of mitral cells run in olfactory tract to primary olfactory cortex

Olfactory cortex is the major center for odor detection and discrimination

Efferent info is integrated with other sensory modalities in the orbital part of the frontal cortex

Other outputs: amygdala, hippocampus, hypothalamus, mediodorsal thalamic nucleusMAINSECTION

Olfactory Cortexprimary olfactory cortexolfactory tractputamennucleus accumbens /olfactory tuberclelateral striate arteriesAt the junction of frontal and temporal cortices

Axons of mitral cells run in olfactory tract to primary olfactory cortex

Olfactory cortex is the major center for odor detection and discrimination

Efferent info is integrated with other sensory modalities in the orbital part of the frontal cortex

Other outputs: amygdala, hippocampus, hypothalamus, mediodorsal thalamic nucleusNucleus accumbens- Reward center- Contains mostly GABAergic neurons- Receives input from the amygdala and hippocampusMAINSECTION

Hippocampustail of caudatedentate gyrusCA1CA3subiculumpre-subiculumpara-subiculumentorhinal cortexinferior temporal areaRoleInputs/OutputsAlzheimers DiseaseInformation FlowMAINSECTION

The hippocampus is involved inMemory processing (especially for spatial orientation)Hippocampal place cells fire when animal is in a particular spatial location, related to surrounding sensory stimuli

Formation of new memoriesHippocampal lesion inability to form new memories (old memories remain intact)

Memory deficits following ischemia or seizuresCA1 is the most commonly damaged brain area after ischemia or epileptic seizuresIschemia cells are depolarized NMDA receptors allow Ca2+ and Na+ to enter cell more depolarization excitotoxicity

Kluver-Bucy SyndromeAssociated with temporal lobe ablationCannot recognize the significance of objects; loss of fear; failure to learn

Alzheimers DiseaseMAINSECTIONHIPP

Inputs/Outputsinfo from multisensory association cortical areasvisual, auditory areas of inferior and superior temporal cortex

perirhinal/entorhinal cortexinputsoutputs/effectshypothalamusHippocampusfeedbackprefrontal / cingulate cortical areasbasal ganglia (ventral)direct OR via ant. thalamic nuc. /mammillary nucleiMAINSECTIONHIPP

Hippocampustail of caudatedentate gyrusCA1CA3subiculumpre-subiculumpara-subiculumentorhinal cortexinferior temporal areato frontal cortex, anterior thalamus, hypothalamusto the neocortexsensory inputs from cerebral cortexRoleInputs/OutputsAlzheimers DiseaseHide Information FlowMAINSECTIONHIPPCLICK

Alzheimers DiseaseCA1SubPreSubParaSubECCA3DG-amyloid plaquestangles (intracellular)CA1Entorhinal cortex and CA1 are severely damaged during early AlzheimersHigh amounts of tangles in these areas

Tangles develop before plaques, but plaques mark beginning of the diseasePlaques are prevalent in the cerebral cortex outside the hippocampal formationMAINSECTIONHIPP

Orbital/Medial Prefrontal Cortex (OMPC)Orbital prefrontal cortexMedial prefrontal cortexinputsoutputs/effectsmultimodal sensory inputsassessment of foodamygdala / hippocampushypothalamus, PAG

control visceral functionsappropriate choicesreward/aversioncontrol of moodMAINSECTION

SleepElectroencephalogram (EEG)StagesAscending Reticular Activating SystemMAIN

Electroencephalogram (EEG)Synchronized waves

High amplitude, low frequency

Represent wave summation

Result when similar events coincide

Ex: waves of sleepDesynchronized waves

Low amplitude, high frequency

Represent wave subtraction

Result when disparate events coincide

Ex: wakefulness, REMMAINSECTION

Stages of SleepStage 1: Alpha waves (still relatively desynchronized)

Stage 2: Sleep spindles

Stage 3-4: Delta waves (synchronized) deep sleep, slow waves

REM (Rapid Eye Movement):Very desynchronized but person is still asleep (paradoxical)No movement except for the extraocular and middle ear muscles, and penile erectionLoss of thermoregulationDreaming, sleep apnea occur; dreaming often reflects experiences over the past few daysInitiated in the rostral pons, LGN, and occipital cortexDepends on cholinergic inputs from the upper pons to thalamus

These stages cycle several times throughout the night.MAINSECTION

Ascending Reticular Activating SystemthalamusNucleus basalis of Meynert (ACh) [not shown]- Implicated in sleep and wakefulness- Projects to all parts of forebrain except basal ganglia- Histology

Laterodorsal tegmental nucleus (LDT) (ACh)

Pedunculopontine tegmental nucleus (PPT) (ACh)

Locus coeruleus (norepinephrine)- Contributes to changes in thalamocortical activity Histology

Raphe nucleus (5-HT)- Caudal spinal cord- Rostral all parts of forebrain- Atlas

Thalamic relay nuclei (e.g., LGN)

Reticular nucleus (GABA)- Receives synapses from thalamocortical, cortico-thalamis axons (connect cortex and principal thalamic nuclei)- Project back onto the principal thalamic nuclei- HistologyThis system is active during wakefulness (and its stimulation causes waking). It is inactive during sleep (and its transection causes coma).NeurotransmittersSleep InitiationMAINSECTION

Ascending Reticular Activating SystemNucleus basalis of Meynert (Ach) [not shown]- Implicated in sleep and wakefulness- Projects to all parts of forebrain except basal ganglia- Histology

Laterodorsal tegmental nucleus (LDT) (Ach)

Pedunculopontine tegmental nucleus (PPT) (ACh)

Locus coeruleus (norepinephrine)- Contributes to changes in thalamocortical activity Histology

Raphe nucleus (5-HT)- Caudal spinal cord- Rostral all parts of forebrain- Histology

Thalamic relay nuclei (e.g., LGN)

Reticular nucleus (GABA)- Receives synapses from thalamocortical, cortico-thalamis axons (connect cortex and principal thalamic nuclei)- Project back onto the principal thalamic nucleiThis system is active during wakefulness (and its stimulation causes waking). It is inactive during sleep (and its transection causes coma).reticular nucleusventrolateral thalamic nucleusRAT BRAIN Stained for GABAMAINSECTIONSYS

Neurotransmitter SystemsBoth norepinephrine and ACh facilitate the responsiveness of post-synaptic neurons.

* The ACh input here is responsible for the paradoxical situation in REM sleep.Ascending Reticular Activating SystemMAINSECTIONSYS

WakefulnessSlow wave sleepREM sleepNorepinephrine(locus coeruleus)ACTIVEINACTIVEINACTIVESerotonin(raphe nuclei)ACTIVEINACTIVEINACTIVEACh(LDT/PPT)ACTIVEINACTIVEACTIVE*

Sleep Initiationsensory afferentseye, spinal cord, etc.CORTEXRETICULARNUCLEUSTHALAMICRELAYNUCLEUS(TRN)Add ascending ACh, NE, 5-HT inputRN inhibition of TRN is blockedTRN cells respond to sensory input with a tonic firing pattern ( wakefulness)Remove ascending ACh, NE, 5-HT inputRN inhibition of TRN is released RN burstingTRN cells cannot respond to sensory input and fire in a rhythmic bursting pattern ( sleep spindles in early sleep stages)thalamocortical neuron= Excitatory (glutamate)= Inhibitory (GABA)WAKEFULNESSSLEEP INITIATIONMAINSECTIONSYSCLICK

MemoryTypes of amnesia

AnterogradeInability to form new memories post-traumaMay be able to form short-term working memories (minutes), but cannot hold themRetrogradeLoss of memories from a few seconds to a couple years pre-traumaMay have more distant memories

Types of memory

Implicit (e.g., procedural)Explicit (a.k.a declarative)WorkingMAINMemory Disorders

Alzheimers DiseaseLewy Body DementiaKorsakovs Syndrome

Implicit MemorySubconsciousSkills/procedures/habitsSimple classical conditioning

Learned by repetition

Examples: riding a bike, playing an instrument

Brain regions involved:Striatum, cortex, cerebellumNot the hippocampus

ProceduralMAINSECTION

Explicit MemoryConsciousEpisodic: places and eventsSemantic: names and facts

Brain regions involvedMedial temporal lobe (hippocampus and associated areas)Entorhinal and perirhinal cortices project to the hippocampus and are especially important in memory

Memory storage: Sensory association cortical areasLateral temporal, parietal, posterior insular cortexMemory consolidation depends on the interaction between these areas and the limbic structures

Is affected in Korsakovs Syndrome and most cases of amnesia

DeclarativeMAINSECTION

Working MemoryShort term (i.e., seconds to minutes)

Example: holding a conversation

Brain regions involvedPrefrontal cortex, areas of the parietal and temporal lobes (relatively unknown)Lesion to dorsolateral prefrontal cortex disrupts performance on short delay tasksNot the hippocampusMAINSECTION

Korsakovs SyndromeLack of vitamin B1 damage along 3rd ventricleSeen in alcoholics due to vitamin deficiency

PresentationAnterograde amnesiaPatients do not have a good awareness of their amnesia (unlike patients with medial temporal lobe lesion)

Involves the mammillary bodies, dorsal thalamus, anterior thalamus3rd ventriclemammillary bodiesNORMALKORSAKOVSno mammillary bodiesMAINSECTION

Lewy Body DementiaClosely related to Parkinsons Disease

Intracellular inclusions of protein -synuclein neuronal dysfunction

Dementia is similar to that found in AlzheimersMAINSECTIONLewy bodies

Language ProcessingCODES:

Visual / orthographicAuditory / phonologicalSyntactic / grammaticalSemantic / meaningArticulatory / speech motor planning

Evidence against the Wernicke-Gershwind model:

Existence of phonological and surface dyslexiaDual route model:

Damage to lexical, whole-word route leads to problems reading irregular words like haveAphasiaMAINNote: This is not a thorough treatment of language processing, but these are the only questions Ive seen on past exams

AphasiaLoss or impairment of language function (caused by brain damage) during speech, hearing, reading, or writingBrocasWernickesClick on an aphasiaMAINSECTION

Brocas AphasiaAphasia with difficulty in language expressionCaused by lesion to the left frontal lobeNote the proximity of Brocas area to the motor cortex, specifically the region controlling the mouth and lipscontrol of mouth/lipsMAINSECTION

Wernickes AphasiaReceptive aphasia with language comprehension difficulty Caused by lesion to the left posterior temporal lobe Note the proximity of Wernickes area to the auditory cortexMAINSECTION

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