FISIOLOGI SUSUNAN SYARAF PUSAT & KELAINAN YANG MUNGKIN TIMBUL Rahmatina B. Herman Bagian Fisiologi FK-UNAND

Overview Central Nervous System (CNS) CNS consists of brain and spinal cord Estimated 100 billion neurons in brain are assembled into complex networks that enable human to: 1. subconsciously regulate internal environment 2. experience emotions 3. voluntarily control movements 4. perceive (be consciously aware of) body and surroundings 5. engage in other higher cognitive processes such as thought and memory

Overview …….Central Nervous System (CNS) No part in brain acts in isolation from other brain regions Networks of neurons are anatomically linked by synapses Neurons throughout brain communicate extensively with each other by electrical and chemical means Even though the brain is a functional whole, it is organized into different regions

Overview …….Central Nervous System (CNS) Physiologically parts of brain can be grouped into: 1. Forebrain: a. Cerebrum: - cerebral cortex - basal nuclei b. Diencephalon: - thalamus - hypothalamus 2. Cerebellum 3. Brain stem

Overview Functions of Brain FOREBRAIN: CEREBRUM Cerebral cortex Sensory perception Voluntary control of movement Language Personality traits Sophisticated mental events, such as thinking, memory, decision making, creativity, self consciousness Basal nuclei Inhibition of muscle tone Coordination of slow, sustained movements Suppression of useless patterns of movements

Overview Functions of Brain FOREBRAIN: DIENCEPHALON Thalamus Relay station for all synaptic input Crude awareness of sensation Some degree of consciousness Role in motor control Hypo-thalamus Regulations of many homeostatic functions, such as temperature control, thirst, urine output, food intake Important link between nervous and endocrine systems Extensive involvement with emotion and basic behavioral patterns

Overview Functions of Brain CEREBELLUM Maintenance of balance Enhancement of muscle tone Coordination and planning of skilled voluntary muscle activity BRAIN STEM (MIDBRAIN, PONS, MEDULLA) Origin of majority peripheral cranial nerves Cardiovascular, respiratory, digestive control centers Regulations of muscle reflexes involved with equilibrium and posture Reception and integration of all synaptic input from spinal cord: arousal and activation of cerebral cortex Role in sleep-wake cycle

Cerebral Cortex 4 pairs of lobes for different activities: 1. Occipital lobes : initial processing of visual input 2. Temporal lobes : initial receiving of sound sensation 3. Parietal lobes : receiving and processing sensory input 4. Frontal lobes : - voluntary motor activity - speaking ability - elaboration of thought

Parietal lobes: Somatosensory Cortex Somesthetic sensation: sensation from surface of body: touch, pressure, heat, cold, pain, etc Proprioception: awareness of body position Sensory homunculus

Parietal lobes: ………..Somatosensory Cortex Localizes source Perceives level of intensity of stimulus Spatial discrimination: shapes of object, distinguish differences in similar subject Projects 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 side

Frontal lobes: Primary Motor Cortex Voluntary control over movement produced by skeletal muscle Motor homunculus Extent of representation in motor cortex is proportional to the precision and complexity of motor skills Controls muscle on the opposite side of body Damage: paralysis on the opposite side

Other Region for Motor Control Supplementary motor area: - Programming complex sequences of movement Premotor cortex - Orienting body and arms toward target Posterior parietal cortex - integration of somatosensory and visual input, important for complex movement Lesions: interfere with performance of integrated movements (not paralysis)

Aspects of Communication Two aspects of communication The sensory aspect (language input) that involving: - ears, and - eyes The motor aspect (language output) that involving: - vocalization, and - its control

Wernicke’s area Broca’s area

Broca’s and Wernicke’s Area: Complex Form of Communication Broca’s area: speaking ability Wernicke’s area: - critical role in understanding both spoken and written massage - formulating coherent patterns of speech - controls articulation of speech Formation in mind of thoughts to be expressed and choice of words to be used Motor control of vocalization and actual act of vocalization itself

Language Disorders Destruction of portions of auditory and visual association areas of cortex can result in inability to understand: - the spoken word, and/or - the written word These conditions are called respectively: - auditory receptive aphasia (word deafness) - visual receptive aphasia (word blindness = dyslexia)

………………….Language Disorders Destruction of Broca’s area: - capable of deciding what he wants to say and vocalizing but cannot make vocal system emit words instead of noises These conditions is called: - motor aphasia

………………….Language Disorders Destruction of Wernicke’s area: - 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 used These conditions is called: - Wernicke’s aphasia

Basal Nuclei (Ganglia Basalis) Play an important inhibitory role in motor control 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

…….Basal Nuclei (Ganglia Basalis) Lesion in subthalamus often leads to flailing movements of entire which is called hemiballismus 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 Parkinson’s disease

Limbic System Is not a separate structure A ring of forebrain structures that surround brain stem and interconnected by intricate neurons pathway Complex interacting networks which is associated with emotions, basic survival and sociosexual behavioral patterns, motivation and learning

Memory Physiologically, memories caused by changes in capability of synaptic transmission from one neuron to the next as a result of previous neural activity The changes in turn cause new pathways or facilitated pathways to develop for transmission of signals through the neural circuits of the brain The new or facilitated pathways are called memory traces

Consolidation of Memory Short-term memory to be converted into long-term memory, it must become “consolidated” That is, chemical, physical and anatomical changes in synapses which are responsible for long-term type of memory This process requires 5-10 minutes for minimal consolidation and  1 hour for strong consolidation

…..Consolidation of Memory Specific parts of brain in memory process is hippocampus Hippocampus can promote storage of memories Hippocampus is not important in reflexive learning

Hippocampus Is one of the most important output pathways from “reward” and “punishment” areas at limbic system These provide background mood and motivations Motivations is the drive in brain to remember experiences and thoughts that are either pleasant or unpleasant

Amnesia Anterograde After 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 amnesia

Amnesia Retrograde Inability to recall memories from the past Degree 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 times Caused by damage in some area of thalamus, because thalamus might play a role in helping “search” memory store house and thus “read out” the memories

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