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1、BCH 4040Aspects of Neuroscience,Lecturer:Prof D TsangOffice:Rm 516B,BMSBEmail:davidtsangcuhk.edu.hkContact:Ms Janny Lee,Rm132,SC Tel:2609 6359,1,Block 1Structure and function of the nervous system,2,2,Outline,Why do we study the brain?Functions of the nervous system(NS)NSs in different animalsNS and
2、 developmentCan we“advance”brain function further?Components of the NS and their functions:Central nervous system(CNS)Peripheral nervous system(PNS)Autonomic nervous system(ANS)Methods for studying brain structure and functionLocalization and lateralization of functions in the CNSDifferences between
3、 male and female brains?Autism,3,3,4,4,Are common beliefs true?,Bulging-forehead a sign of longevity?頭 大=聰明?May be suffering from hydrocephalus(腦水腫)Brain size is generally related to life expectance,God of longevity,Why do we study the brain?,Weighs 1,300 1,500 gUtilizes 1/5 total oxygen1/4 Blood fl
4、ows thro it Complexity and diversity:Contains many cell types;made up of about 100 billion neurons;organized into exquisitely complex circuitsresponding to experience,drugs,disease,and injury“The most complex living structure on the universe”(Society for Neuroscience)Makes us who we are-individualit
5、y,5,Functions of the nervous system,Organize and direct behavior(speech,reflex)Monitor the outside world with eyes,ears.Learning and memory(survival,improvement)Thinking and personality generate ideasCare and upkeeping of body via autonomic nervous system(ANS)Stimulate development and maturation of
6、body Control of behavior(dysfunction causes depression,schizophrenia,etc),6,6,7,7,Figure 9-1:Evolution of the nervous system,Evolution of the nervous system,Complex,Simple,Forebrain,Size,Evolution of the Brain,Reptilian Paleomammalian Neomammalian,8,Large portion devoted to higher functions(reasonin
7、g,cognition)in human,Brain development and function,9,Embryonic Development of NS,10,NS develops very early in life,11,Schematic flowchart of human brain development,Ref:http:/en.wikipedia.org/wiki/Neural_development,12,Schematic flowchart of human spinal cord development,13,Monitoring brain develop
8、ment,14,15,15,Brain is almost fully developed at 2 yrs of age,16,17,18,Measurement of body length and weight are included to gauge infant development,Timeline of child development-1,19,19,mos,Timeline of child development-2,20,20,Growth and development is closely related to the development of the br
9、ain,mos,Can we elevate our brain function further?,21,Human brain cannot get smarter,Human brains capacity depends on speedy interlinks among different parts of brain Brain power requires disproportionate energy consumptionPhysically impossible for humans to provide extra amounts of energy and oxyge
10、nHuman intelligence faces tight constraints Ed Bullmore,Dept of psychiatry at Cambridge,22,23,Memory,Ability to store,retain,and subsequently retrieve informationThree types:sensory,short-term and long term Relationship,24,25,26,Active ingredients:Flavonoids:kaempferol;quercetin;isorhamnetin Terpeno
11、ids:ginkgolides 銀杏內酯(A,B,C bilobalide 白果內酯 Treatments(?):Cerebral disorders(Alzheimers disease)Neuroprotectant in hypoxia/ischemia Vascular diseases A smart drug Enhance memory?,Ginkgo Biloba leaves白果葉,Ginkgo Biloba leaves(白果葉),Results conflicting,Ginkgo extract may have 3 effects:Improves blood flo
12、w(microcirculation)Protects against oxidative cell damage Blocks many of the effects of platelet-activating factor(platelet aggregation/blood clotting cardiovascular,renal,respiratory and central nervous system disorders,27,28,?,29,Component of plasma membraneHigh concentrations in retina and brain:
13、Brain contains 60%lipids(myelin)Most are phospholipidsNo RDA for Omega-3 fatty acids(1-2 fatty fish serving/wk)Found in humans but not in cows milk Baby formulae have DHA and EPA added,EPA and DHA and brain,Choline and Memory,Choline not synthesized in brain Choline+acetyl CoA acetylcholine Evidence
14、Neuropathological:Cholinergic transmitter in AlzheimerPsychopharmacological:Anti-cholinergic drugs(e.g.,Scopolamine,short-term memory)Clinical:Tacrine(cholinesterase inhibitor)+lecithin improves memory in Alzheimer patientsSourcesEgg yolk(lecithin),meat and legumes,low in fruits&vegetablesRDA:0.4 0.
15、9 mg/day,30,Memory and the brain,Mechanisms of memory are not completely understoodBrain areas:hippocampus,amygdala,striatum,etc are thought to be involved in specific types of memoryFor example,the hippocampus is believed to be involved in spatial learning and declarative learning(information that
16、is explicitly stored and retrieved),while the amygdala is thought to be involved in emotional memoryMemory(and learning)not solely dependent on specific brain regions,31,32,Exercise your brain,What kind of table is edible?,Components of the NS,33,33,34,Nervous system-divisions,Central nervous system
17、(中樞神經系統;CNS)Consists of brain and spinal cord(brain thro cranial nerves;spinal cord and the PNS regulates virtually all human activity)Function:central control of body functions Peripheral nervous system(周邊神經系統;PNS)Contains mainly sensory and motor nerve fibersFunction:relay sensory(e.g.,from recept
18、ors sensory fiber(heat,pain to the brain),motor(e.g.,from motor cortex to muscles movement of limbs,mechanic.)and other messagesAutonomic nervous system(自主神經系統;ANS)*Sympathetic(交感神經系統)and parasympathetic(副交感神經系統)NS Activated/Controlled by centers in the hypothalamus,brain stem and spinal cordFunctio
19、n:controls smooth muscle,gland secretion(sweat gland)blood vessel(e.g.,dilation&contraction)and viscera movements,34,*Part of the PNS,Structures and functions of the CNS,35,36,36,Central Nervous System(CNS),Consists ofBrainSpinal cordBrain and spinal cord continuous with each other,37,Brain,Control
20、center of CNS and body responsible for behavior and other body activitiesLocated in the head;protected by bony skull(Advantage?)Close to primary sensory apparatus of vision,hearing,balance,sense of taste,and olfaction(Advantage?)Extremely complex-brain contains 100 billion neurons,each linked to tho
21、usands of neurons(Suggesting what?),37,Bony skull encases the brain3 tough meninges separate the skull and the brain,38,38,SkullDura mater(firmly attached to skull),Arachnoid LayerPia Mater(innermost layer firmly attached to brain,contains many blood vessels),Skull and meninges,Brain,Division of the
22、 brain,The brain is divided into 2 hemispheres,39,Brain-cerebrum,Largest part of the brainCovered with a layer of gray matter(cerebral cortex)Separated into 2 distinct but symmetrical hemispheres(L&R)Each divided into 4 lobes(frontal,parietal,temporal and occipital)Hemispheres linked by the corpus c
23、allosum transfers information btw the 2 hemispheres to coordinate localized functions Left controls the right side&vice versa Cerebral dominance:Speech area is located in the left while areas that govern spatial perceptions reside in the right,40,40,41,Lateralization of functions in human cerebral h
24、emispheres,41,42,Brain Overview,42,The lobes are named after the bones of the skull that surround them,43,Functions of different cerebral areas,44,Phrenologists(腦理學家)attempted to localize brain function on the basis of bumps and ridges on the skull,The lobes of the cerebral hemispheres,Planning,deci
25、sion making speech,Sensory,Auditory,Vision,Lobes of the cerebral hemispheres,45,46,46,Front,Speech,Taste,Coordinates movements,Planning,reasoning&concentrate,Pain,Muscle movements,hearing,Vision,Left,Electrical stimulation to localize functions,47,47,Left side,48,48,Localization of sensory function,
26、Left hemisphere,More important function“occupy”larger area,49,49,50,50,(Interprets sensory information),51,51,Conclusion:many brain areas are involved in executing a function,52,Localization of function advantage or disadvantage?,Specialization(dedicated neural circuits;integration of function)Compl
27、exity(subdivision of function)Efficiency(short axons faster transmission of impulse;fewer ion pumps utilize less energy)Extra space for other functions;complexity Disadvantage injury/damage severe loss of function,52,53,53,Brain parts associated with disorders,Though some functions are mainly locali
28、zed in certain brain areas,they require the participation of other areas forming pathways(circuits),54,Message,Structures under the cortex and their functions,Basal gangliaAmygdala Diencephalon,55,56,Spinal cord,57,Location of some Internal structures:caudate nucleus and amygdala,Basal ganglion,Cons
29、ists of 5 large subcortical nuclei:caudate nucleus,putamen,globus pallidus,subthalamic nucleus and substantia nigra2 sets,mirrored in L and R hemispheresLocation:below the cerebral cortex and above the thalamus;caudate nucleus,putamen and globus pallidus in front and subthalamic nucleus and substant
30、ia nigra at caudal endInterconnected with the cerebral cortex,thalamus and brainstem(reticular formation)Functions:motor control(voluntary movements and establishing postures),cognition,emotions and learning,58,Caudate nucleus,One within each hemisphereA C-shape structure with a wider head at the fr
31、ont,tapering to a body and a tailFunction:control voluntary movement and important in learning and memoryHighly innervated by dopamine neurons(degeneration Parkinsons disease),59,59,Amygdala,Latin for almond,2 setsLocation:deep within the medial temporal lobesFunctions:Emotion e.g.,good/bad,feeling
32、sad,scared,or silly,or gladSense of smell and pheromone-processing Modulate memory consolidation:primary roles in the formation and storage memories associated with emotional events,60,60,Bottom view,61,Diencephalon,ThalamusHypothalamus,62,63,63,Relative locations of some internal organs,64,Thalamus
33、,2 sets,one in each hemisphere Location:between the brain stem and the cerebrumFunction:A translator:Inputs from basal ganglia and cerebellum are processed into a form readable and relays them to appropriate parts of the cerebral cortex motor outputsProcess and relay sensory information(auditory,som
34、atic,visceral,gustatory and visual)to cerebral cortexRegulates sleep,wakefulness and consciousnessDamage permanent comaThalamic syndrome(strokes)-burning or aching sensation on one half of a body(contralateral hemianaesthesia),Hypothalamus,Located below thalamus,just above brain stem;about the size
35、of an almondLinks the NS to the endocrine system via the pituitary gland-synthesizes and secretes hypothalamic-releasing/inhibiting hormones,in turn controls secretion of pituitary hormonesControls body temperature,hunger,thirst,fatigue,anger,and circadian cycles;responsible for activities of the AN
36、SResponsive to:leptin,ghrelin,angiotensin,insulin,pituitary hormones,cytokines,plasma concentrations of glucose and osmolarity,etc,65,65,Other structures,CerebellumA separate structure attached to the bottom of the brain,tucked underneath the cerebral hemispheresFunction:Maintains posture,balance an
37、d coordination of movementBrain stemConnects the rest of the brain to the spinal cord;composed of:midbrain.pons and medulla oblongataNerve connections of the motor and sensory systems from the main part of the brain to the rest of the body pass through itIn charge of functions needs to stay alive br
38、eathing(respiration rate),digesting food(gastrointestinal activity),and circulating blood(heart rate),66,67,Movement control Roles ofbasal ganglia and cerebellum,Both basal ganglia and cerebellum modify movement constantlyMotor cortex sends information to both,and both structures send information ri
39、ght back to cortex via the thalamus adjustmentOutputs of the cerebellum are excitatory,while the basal ganglia are inhibitoryThe balance between these 2 systems allows for smooth,coordinated movement,and a disturbance in either system will show up as movement disorders,Spinal cord,45 cm long in men
40、and 42 cm long in women 5 regions:8 cervical segments12 thoracic segments5 lumbar segments5 sacral segments1 coccygeal segment Functions:Integration of low-level functions(e.g.,jerk reflex)Monitored at all times by higher centers,68,68,Spinal cord,69,69,White matter contains myelinated nerve fibersG
41、ray matter contains mainly cell body and dendritesDH,dorsal horn;VH,ventral horn;cc,central canal,Motor,Sensory,Spinal cord-function,General:Transmission of signals between brain and rest of the body but also contains neural circuits that can independently control/integration of low-level functions(
42、e.g.,jerk reflex)Others:(a)as a conduit for motor information,which travels down the spinal cord;(b).as a conduit for sensory information,which travels up the spinal cord.(c).Serve as a center for coordinating certain reflexesInjury:paraplegia,quadriplegia or full body paralysis below the site of in
43、jury to the spinal cord,70,Peripheral Nervous System(PNS),NS outside the CNS,consists of the nerves and ganglia(mass of neuronal cell bodies)Main function:connect the CNS to the limbs and organsUnlike CNS,PNS is naked Divisions:Sensory-somatic nervous system(軀體神经系統)Consists of 12 pairs of cranial ne
44、rves and 31 pairs of spinal nervesRelies information between CNS and ext.environment Autonomic nervous system(ANS;自主神經系統)Sympathetic(交感神經系統)Parasympathetic(副交感神經系統)Enteric,71,Autonomic nervous system自主神經系統(ANS),72,72,ANS,Consists of sensory and motor neurons that run between CNS(esp.hypothalamus and
45、 medulla oblongata)and various internal organs(heart,lungs,viscera,and exocrine and endocrine glands)Responsible for monitoring conditions in the internal environment and bringing about appropriate changes regulates heart rate,digestion,respiration rate,salivation,perspiration,pupil diameter,dischar
46、ge of urine,sexual arousal,etc with major function aim maintaining homeostasisMain components:Parasympathetic nervous systemSympathetic nervous system,73,73,74,Sacral,Lumbar,Thoracic,Cervical,ANS,Functions of sympathetic and parasympathetic NSs,Sympathetic:functions in actions requiring a quick resp
47、onse,dealing with response to stress and danger,metabolic rate,elevating blood pressure,breathing rate,and blood flow to the musclesParasympathetic functions in actions that do not require an immediate response and active during rest,sleeping,and digesting food,lowering metabolic rate,slowing activi
48、ty,synthesizing glycogen,and restoring blood pressure and resting heartbeatThey are complementary in nature rather than antagonistic-sympathetic as the accelerator and the parasympathetic as the brake,75,Neurotransmitters in ANS,At the effector organs,sympathetic neurons release noradrenalin(NA),to
49、act on noradrenergic receptors,with the exception of the sweat glands(acetylcholine,ACh)and the adrenal medulla(adrenalin)Parasympathetic system,ganglionic neurons use ACh to stimulate muscarinic receptors,76,Relation between CNS,SSNS and ANS,77,Methods for studying brain function,78,Studies of brai
50、n function,Animal and cellular studiesArgument-equivalent to human?Old(static)Morphological/histologicalPost-traumatic and pathological observationsProblem-Cause?Result?Recent(neuroimaging)Computerized tomography(CT scan)Positron emission tomography(PET)Magnetic resonance imaging(MRI),79,79,What is
