FISIOLOGI SUSUNAN SYARAF PUSAT & KELAINAN YANG MUNGKIN TIMBUL

FISIOLOGISUSUNAN SYARAF PUSAT& KELAINAN YANG MUNGKIN TIMBULRahmatina B. HermanBagian FisiologiFK-UNAND

1Overview Central Nervous System (CNS)CNS consists of brain and spinal cordEstimated 100 billion neurons in brain are assembled into complex networks that enable human to:1. subconsciously regulate internal environment2. experience emotions3.voluntarily control movements4. perceive (be consciously aware of) body and surroundings5.engage in other higher cognitive processes such as thought and memory2..Overview Central Nervous System (CNS)No part in brain acts in isolation from other brain regionsNetworks of neurons are anatomically linked by synapsesNeurons throughout brain communicate extensively with each other by electrical and chemical meansEven though the brain is a functional whole, it is organized into different regions 3..Overview Central Nervous System (CNS)Physiologically parts of brain can be grouped into:1.Forebrain: a.Cerebrum:-cerebral cortex-basal nucleib.Diencephalon:-thalamus-hypothalamus2. Cerebellum3.Brain stem4

5Overview Functions of BrainFOREBRAIN: CEREBRUMCerebral cortexSensory perceptionVoluntary control of movementLanguagePersonality traitsSophisticated mental events, such as thinking, memory, decision making, creativity, self consciousnessBasal nucleiInhibition of muscle toneCoordination of slow, sustained movementsSuppression of useless patterns of movements6..Overview Functions of BrainFOREBRAIN: DIENCEPHALONThalamusRelay station for all synaptic inputCrude awareness of sensationSome degree of consciousnessRole in motor controlHypo-thalamusRegulations of many homeostatic functions, such as temperature control, thirst, urine output, food intakeImportant link between nervous and endocrine systemsExtensive involvement with emotion and basic behavioral patterns7..Overview Functions of BrainCEREBELLUMMaintenance of balanceEnhancement of muscle toneCoordination and planning of skilled voluntary muscle activity BRAIN STEM (MIDBRAIN, PONS, MEDULLA)Origin of majority peripheral cranial nervesCardiovascular, respiratory, digestive control centersRegulations of muscle reflexes involved with equilibrium and postureReception and integration of all synaptic input from spinal cord: arousal and activation of cerebral cortexRole in sleep-wake cycle8Cerebral Cortex4 pairs of lobes for different activities:1. Occipital lobes: initial processing of visual input 2.Temporal lobes:initial receiving of sound sensation3.Parietal lobes:receiving and processing sensory input4.Frontal lobes:- voluntary motor activity- speaking ability- elaboration of thought9

10Parietal lobes: Somatosensory CortexSomesthetic sensation: sensation from surface of body: touch, pressure, heat, cold, pain, etcProprioception: awareness of body positionSensory homunculus11..Parietal lobes: Somatosensory CortexLocalizes source Perceives level of intensity of stimulusSpatial discrimination: shapes of object, distinguish differences in similar subjectProjects the sensory input to adjacent higher sensory areas for further elaboration, analysis, and integration Receive sensory input from the opposite side of body Damage: sensory deficit/losses of the opposite side12Frontal lobes: Primary Motor CortexVoluntary control over movement produced by skeletal muscleMotor homunculusExtent of representation in motor cortex is proportional to the precision and complexity of motor skillsControls muscle on the opposite side of bodyDamage: paralysis on the opposite side13Other Region for Motor ControlSupplementary motor area:-Programming complex sequences of movementPremotor cortex-Orienting body and arms toward targetPosterior parietal cortex-integration of somatosensory and visual input, important for complex movementLesions: interfere with performance of integrated movements (not paralysis)14Basal Ganglia/ Basal NucleiBasal ganglia consist of:1. Caudate nucleus2. Putamen3. Globus pallidus4.Substantia nigra5.Subthalamic nucleus15..Basal Ganglia/ Basal NucleiPlay an important inhibitory role in motor controlFunction and role of basal gangliaFunction of basal ganglia in executing patterns of motor activity The Putamen CircuitRole of basal ganglia for cognitive control of sequences of motor patterns The Caudate CircuitFunction of basal ganglia to change the timing and to scale intensity of movements16..Basal Ganglia/ Basal NucleiClinical syndromes resulting from damage of basal ganglia:1. Athetosis2. Hemiballismus3. Chorea4. Parkinsons disease5. Huntingtons disease171. The Putamen CircuitPrimary putamen circuit: from and to primary motor cortex3 ancillary circuits in close association to primary putamen circuits:- putamen external globus pallidus subthalamus motor cortex-putamen internal globus pallidus substantia nigra motor cortex-external globus pallidus subthalamus external globus pallidus18..1. The Putamen CircuitFunction of putamen circuit is to control complex patterns of motor activity such as:-writing letters of alphabet-cutting paper with scissors-hammering nails-shooting basketball through a loop-passing a football-throwing a baseball-movements of shoveling dirt-some aspects of vocalization-control movements of eyes-any other of skilled movements

19Abnormalities of putamen circuit Certain patterns of movement become severely abnormal, such as:-Lesions in globus pallidus frequently lead to spontaneous and often continuous writhing movements of a hand, an arm, the neck, or the face which is called athetosis-Lesion in subthalamus often leads to flailing movements of entire which is called hemiballismus-Multiple small lesions in putamen leads to flicking movements in hands, face and other parts of body, which is called chorea-Lesions of substantia nigra leads to common and extremely severe disease of rigidity, akinesia, and tremors known as Parkinsons disease..1. The Putamen Circuit202. The Caudate CircuitCerebral cortex caudate nucleus internal globus pallidus to relay thalamus prefrontal, premotor, and supplementary motor areas of cerebral cortex21..2. The Caudate CircuitFunction of caudate circuit:Cognitive control of sequences of motor patterns which is concerned with putting together sequential patterns of movementCognitive control of motor activity determines subconsciously which patterns of movement will be used together and in what sequence to achieve a complex goal22A good example when a person to see a lion approach and the respond instantaneously and automatically:1. turning away from the lion2. beginning to run3.even attempting to climb a treeWithout cognitive function the person might not have the instinctive knowledge, without thinking for too long time, to respond quickly and appropriately..2. The Caudate Circuit233. Other Function of BGFunction of basal ganglia to change time and to scale intensity of movementsTwo important capabilities:1. to determine how rapidly movement is to be performed2.to control how large movement will beFor instance:-writing letter a rapidly or slowly, or a small a on paper and large a on board-use fingers for writing or the whole arm at another time

24Parkinsons DiseaseAlso known as paralysis agitansResults from widespread destructions of portion of substantia nigraCharacterized by:-rigidity of musculature of body-involuntary tremor -serious difficulty in initiating movement, called akinesiaCauses: almost entirely unknown

25..Parkinsons DiseaseTheoretically:destruction of dopaminergic neurons in substantia nigra would allow caudate nucleus and putamen to become overly active and possibly cause continuous output of excitatory signals to corticospinal motor control system26Huntingtons DiseaseAlso known as Huntingtons choreaIs hereditary disorder that usually begin in the fourth or fifth decade of lifeCharacterized by:-flicking movements at individual joints at first-then progressive severe distortional movements of entire body-severe dementia develops along with motor dysfunction27..Huntingtons DiseaseAbnormal movements of Huntingtons disease are believed to be caused by loss of most of cell bodies of GABA-secreting neurons in caudate nucleus and putamen, therefore loss of inhibition in globus pallidus and substantia nigraIt is believed to allow spontaneous outbursts of globus pallidus and substantia nigra activity that cause distortional movementDementia in Huntingtons disease probably results from loss of acetylcholine-secreting neuronsPerhaps especially in thinking areas of cerebral cortex28

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31Aspects of CommunicationTwo aspects of communicationThe sensory aspect (language input) that involving: -ears, and -eyesThe motor aspect (language output) that involving: -vocalization, and -its control32

Wernickes areaBrocas area33Brocas and Wernickes Area:Complex Form of CommunicationBrocas area: speaking abilityWernickes area:-critical role in understanding both spoken and written massage-formulating coherent patterns of speech-controls articulation of speechFormation in mind of thoughts to be expressed and choice of words to be usedMotor control of vocalization and actual act of vocalization itself34

35Language DisordersDestruction of portions of auditory association areas of cortex -auditory receptive aphasia (word deafness): in inability to understand the spoken word Destruction of portions of auditory association areas of cortex -visual receptive aphasia (word blindness = dyslexia): in inability to understand the written word36..Language DisordersDestruction of Brocas area:- motor aphasia: capable of deciding what he wants to say and vocalizing but cannot make vocal system emit words instead of noisesDestruction of Wernickes area:-Wernickes aphasia: capable of understanding either the spoken word or the written word but are unable to interpret the thought to be expressed and choice of words to be used37Limbic SystemIs not a separate structureA ring of forebrain structures that surround brain stem and interconnected by intricate neurons pathwayComplex interacting networks which is associated with emotions, basic survival and sociosexual behavioral patterns, motivation and learning38

39MemoryPhysiologically, memories caused by changes in capability of synaptic transmission from one neuron to the next as a result of previous neural activityThe changes in turn cause new pathways or facilitated pathways to develop for transmission of signals through the neural circuits of the brainThe new or facilitated pathways are called memory traces40Consolidation of MemoryShort-term memory to be converted into long-term memory, it must become consolidatedThat is, chemical, physical and anatomical changes in synapses which are responsible for long-term type of memoryThis process requires 5-10 minutes for minimal consolidation and 1 hour for strong consolidationHippocampus: specific parts of brain in memory process41Hippocampusis one of the most important output pathways from reward and punishment areas at limbic systemThese provide background mood and motivations Motivations is the drive in brain to remember experiences and thoughts that are either pleasant or unpleasantcan promote storage of memoriesis not important in reflexive learning42Amnesia AnterogradeAfter removal of hippocampi:-memory for information stored in brain before hippocampal removal is not seriously affected-but after removal that person has no capability for storing verbal and symbolic types of memories in long-term memory, or even in intermediate long-term memory> So this person is unable to establish new long-term memory which is basis of intelligence or learning. >This is called anterograde amnesia43Amnesia RetrogradeInability to recall memories from the pastDegree of amnesia for recent events is likely to be much greater than for events the distant past, because memories for events distant past have been rehearsed so many timesCaused by damage in some area of thalamus, because thalamus might play a role in helping search memory store house and thus read out the memories44

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