Organization of the Central Nervous System Zhifeng Liang, PhD Mar 22, 2018
Nervous system Central nervous system (CNS) Brain ( 脑 ) Spinal cord ( 脊髓 ) Peripheral nervous system Cranial nerves ( 脑神经 ) Spinal nerves ( 脊神经 ) Anatomy: different Function: intertwined with CNS, receive, transmit and process information
Orientation: 3 main axis Dorsal (superior) Rostral (anterior) Caudal (posterior) Lateral Medial Lateral Ventral (inferior) Rostral Dorsal Ventral Caudal
Orientation: 3 section planes
Coordinates of Brain Structures: stereotaxic methods Location of a target expressed as: RD (rostral-caudal): xx mm ML (medial-lateral): xx mm DV (dorsal-ventral): xx mm
Major Components of the CNS I: Brain (6 divisions) Cerebral hemispheres Cerebellum Diencephalon Midbrain Pons Medulla II: Spinal cord cerebral hemispheres corpus callosum diencephalon midbrain cerebellum pons medulla Spinal cord
Spinal Cord: External Profile 颈椎 (C) 头后部, 颈部, 上肢 胸椎 (T) 躯干上半部 下肢 腰椎 (L) 尾椎 (S)
Spinal Cord: internal Profile
Spinal Cord: internal Profile
脊髓的功能 ( 一 ) 传导功能 : 机体感觉 > 脊髓 > 脑 > 脊髓 > 躯干四肢 内脏运动 ( 二 ) 反射功能 : 躯体反射 ( 如膝跳反射 ), 内脏反射 单突触反射 脊髓损伤可造成感觉和运动能力缺失
Medulla Similar to the spinal cord I: 延髓是生命中枢 :1) 呼吸中枢 ;2) 心血管调节中枢 ;3) 吞咽和呕吐中枢 II: 传导触觉 听觉, 平衡及来自大脑 脊髓的信息 中缝核 (5-HT) 上橄榄核 耳蜗腹核 耳蜗背核 第 4 脑室 声源定位 声音频率等 下橄榄核 ( 发出 climbing fiber 至小脑 ) 来自大脑皮层 红核 上丘 前庭和脊髓的信息 锥体束
Pons Ventral portion (pontine nuclei, relay information about movement and sensation from cortex to cerebellum) Dorsal portion (respiration, taste and sleep) 脑桥网状结构 皮层 顶盖 三叉核 脊髓和网状结构信息 脑桥核 脑桥是大脑和小脑联系的 桥梁 参与大脑和小脑发起的随意运动的调节 ; 参与呼吸 血压 睡眠等生理功能的调节 ( 臂旁核和中缝核团的 5-HT, 及蓝斑的 NE)
Midbrain Linkage between components of the motor system: cerebellum, basal ganglia, and cerebral hemisphere Visual (tectum) and auditory relay Eye movement 中脑导水管周围灰质 黑质 ( 多巴胺 ) 上丘 腹侧被盖区 VTA 奖赏系统与药物成瘾等有关 中央导水管 联系大脑 小脑和脊髓 红核 中脑是视听觉 ( 上丘和下丘 ) 的调节和整合中枢 导水管周围灰质参与心血管活动和呼吸活动的调节 ; 含阿片肽调质, 调制痛觉传递和整合 调节眼睛运动等 黑质多巴胺能神经元变性可引起纹状体内多巴胺水平下降, 从而导致震颤性麻痹 ( 帕金森氏症 )
Major Components of the CNS I: Brain (6 divisions) Cerebral hemispheres Cerebellum Diencephalon Midbrain Pons Medulla II: Spinal cord cerebral hemispheres corpus callosum diencephalon midbrain cerebellum pons medulla Spinal cord
小脑的位置和外形 位置 : 大脑半球后方, 覆盖在脑桥及延髓之上, 横跨在中脑和延髓之间 ; 外形 : 中部狭窄称小脑蚓, 两侧膨大部称小脑半球, 小脑下面靠小脑蚓两侧小脑半球突起称小脑扁桃体
小脑的分叶和机能 小脑前叶 ( 旧小脑 / 脊髓小脑 ): 鸟类 爬行类已发展出 ; 调节躯干 四肢肌紧张 ( 加强或抑制 ), 紧张加强持久呈 角弓反张 状 小脑后叶 ( 新小脑 / 大脑小脑 ): 高等哺乳动物特有, 随同大脑皮层的发展 ; 协调随意运动, 准确化运动的速率 范围 力量和方向等 绒球小结叶 ( 原小脑 / 前庭小脑 ): 基本上是鱼类的整个小脑 ; 负责维持机体平衡, 但不影响四肢的协调运动
Sagittal section: 小脑的内部结构 灰质 : 致密折叠的小脑皮层, 占据 1/10 体积, 含有最多的神经元 ( 胞体小 ) 白质 :Myelinated nerve fibers running to and from the cortex (Tree of life) 灰质核 : 新小脑核 : 齿状核 (nucleus dentatus) 旧小脑核 : 栓状核 (nucleus embsliformis) 球状核 (nucleus globiformis) 顶核 (nucleus fastigii)
Major components of the CNS I: Brain (6 divisions) Cerebral hemispheres ( 大脑 ) Cerebellum ( 小脑 ) Diencephalon ( 间脑 ) Midbrain ( 中脑 ) Pons ( 脑桥 ) Medulla ( 延髓 ) II: Spinal cord 大脑胼胝体间脑中脑小脑脑桥延髓脊髓
I: Epithalamus( 上丘脑 ) 包括 : 松果体 缰核 丘脑髓纹和连合下器, 参与调节昼夜节律 性成熟 情绪等 Diencephalon( 间脑 ) II: Hypothalamus( 下丘脑 ) 与前脑 边缘系统 脑干 脊髓有相互联系, 与脑垂体相连接, 参与内脏活动和内分泌功能的调节 保证内环境稳定 ; ( 与松果体一起 ) 调节生物节律, 调节体温 ( 视前区 ), 调节摄食和饮水, 参与应激反应和情绪表达 III: Thalamus(* 丘脑 *)
丘脑的主要机能 : 信息中转站 Relay Nuclei: Most of thalamus consists of relay nuclei: receive inputs from pathways, process the input and send it on to a particular region of cerebral cortex. All sensory modalities except olfaction have a relay in the lateral thalamus that projects to a specific region of cerebral cortex.
丘脑的特异投射 Ventral posterior lateral nucleus (VPL): somatosensory relay from body Ventral posterior medail nucleus (VPM): somatosensory relay from cranial nerves Lateral geniculate nucleus (LGN): visual relay Medial geniculate nucleus (MGN): auditory relay Ventral lateral nucleus (VLN): : motor relays from cerebellum and basal ganglia 运动 听觉 触觉 视觉
丘脑的非特异性广泛投射 Pulvinar nucleus: Visual and other sensory inputs are processed and relayed to large regions of parietal, temporal and occipital association cortices Mediodorsal nucleus: Limbic relays and projections involved in cognitive functions are processed here and relayed to frontal association cortex Reticular nucleus (outer shell): not project to cortex, only provides feedback to thalamus 运动 触觉 听觉 视觉
Other functions: 丘脑不仅仅是中转站 Local processing within the nucleus; Modulation by brain stem inputs (e.g. adrenergic and serotonergic monoamine systems); Sensory gating through: Inhibitory feedback from the reticular neucleus; Excitatory feedback from the neocortex.
Major components of the CNS I: Brain (6 divisions) Cerebral hemispheres( 大脑 ) Cerebellum ( 小脑 ) Diencephalon ( 间脑 ) Midbrain ( 中脑 ) Pons ( 脑桥 ) Medulla ( 延髓 ) 大脑胼胝体间脑中脑小脑脑桥延髓 II: Spinal cord 脊髓
Cerebral hemispheres Largest region of the human brain Corpus callosum Components: cerebral cortex corpus callosum basal ganglia amygdala hippocampal formation 大脑皮层 胼胝体 基底节 杏仁体和海马结构
Mammalian brains Species Weight (g) adult human 1,300-1,400 newborn human 350-400 Pithecanthropus Man 850-1,000 sperm whale 7,800 elephant 6,000 bottle-nosed dolphin 1,500-1,600 chimpanzee 420 rhesus monkey 90-97 dog (beagle) 72 cat 30 squirrel 7.6 alligator 8.4 owl 2.2 rat (400 g weight) 2 goldfish 0.097 green lizard 0.08
脑重和体重的比例
皮层的分区 Increased surface: 脑沟 -sulci 脑回 -gyri Main 4 lobes: Temporal lobe Frontal lobe Parietal lobe Occipital lobe Frontal lobe ( 额叶 ) Parietal lobe ( 顶叶 ) Occipital lobe ( 枕叶 ) Lateral sulcus (sylvian fissure) Temporal lobe ( 颞叶 )
Large Variations of Cerebral Structure Group Variation Individual Variation Leonard et al., 2006 Tang et al., 2010
Function of Cerebral Cortex The cerebral cortex is concerned with cognitive functioning (not the spinal cord, brain stem, or diencephalon) Process sensory information & deliver motor commands Specialized areas: Primary : first stage in cortex Primary visual cortex Primary auditory cortex Primary somatosensory cortex Primary motor cortex Frontal lobe Primary auditory cortex Lateral sulcus (sylvian fissure) Primary motor cortex Temporal lobe Parietal lobe Primary somatosensory cortex Occipital lobe Primary visual cortex Primary vestibular cortex?
How is cerebral cortex is organized? Layers and columns
Cerebral Cortex is organized in layers
Layers in cerebral cortex Varied across areas, typically have 6 layers Dendrites, axons Small granule cells; dendrites from V, VI 分子层 外颗粒层 Small pyramidal cells; dendrites from V, VI 外锥体层 Granule cells Large pyramidal cells; dendrites from III, IV 内颗粒层 内锥体层 Variety of neurons; dendrites from III, IV 多形层
Neuron types in the brain Projection neurons: Pyramidally shaped; layers III, V, VI; Excitatory glutamate Local interneuron: Across all layers; Inhibitory GABA; Basket cells: body Chandelier cells: axon Martinotti cells: dendrites
New Approach to Cell Type Classification http://celltypes.brain-map.org/
Cortical Columns/Cluster ( 功能柱 ) Columns: small cortical areas within which all neurons have similar response properties. Believed to be the fundamental computational modules of neocortex. cylinder fraction of a millimeter in diameter more columns in higher vertebrates
Cerebral hemispheres Largest region of the human brain Corpus callosum Components: cerebral cortex corpus callosum basal ganglia amygdala hippocampal formation 大脑皮层 胼胝体 基底节 杏仁体和海马结构
Corpus callosum ( 胼胝体 ) 胼胝体 : 连接左右两侧大脑半球的横行神经纤维束, 是大脑半球中最大的连合纤维 胼胝体的作用 : 大脑半球之间的信息交流 R.W.Sperry:1981 Nobel Prize 在动物 ( 猫, 猴 ) 上切断胼胝体, 影响大脑两半球之间的信息交流 裂脑人的研究 : 癫痫病人切除胼胝体后, 副作用出现人格分裂倾向, 提示大脑具有两个意识 大脑两半球的不对称性 : 左半球 : 语言, 数学运算右半球 : 图画, 艺术, 音乐
Corpus callosum ( 胼胝体 ) 并非所有哺乳动物都具有胼胝体 : 有袋类 (marsupial, 如袋鼠 负鼠 ) 和单孔类 (monotreme, 如鸭嘴兽 ) 没有 负鼠 : 没有胼胝体, 具有发达的前联合 (anterior commissure) 当描述脑结构的功能时, 一定要有限定范围! http://brainmaps.org
Cerebral hemispheres Largest region of the human brain Corpus callosum Components: cerebral cortex corpus callosum basal ganglia amygdala hippocampal formation 大脑皮层 胼胝体 基底节 杏仁体和海马结构
Basal Ganglia( 基底核 ) Striatum( 纹状体 ): Caudate( 尾核 ) Putamen( 壳核 ) Globus Pallidus( 苍白球 ) Substantial nigra( 黑质 ) Subthalamic nucleus( 底丘脑 ) 主要功能为自主运动的控制 它同时还参与记忆, 情感和奖励学习等高级认知功能 基底核的病变可导致多种运动和认知障碍, 包括帕金森氏症和亨廷顿氏症等 壳核 尾核 外苍白球 内苍白球
Amygdala( 杏仁核 ) 参与情绪的表达 动机的产生和学习记忆的功能 特别是与害怕情绪的表达 恐怖环境中的学习记忆有关, 引发应急反应 ( 学习害怕 ) 刺激杏仁核 : 引起恐惧和忧虑 损毁杏仁核 : 记忆恐惧受损, 如忘记遇到遭遇抢劫的细节
Hippocampus( 海马 ) Greek: hippo = horse kampos = sea monster 短期记忆 : 新经历的事件空间感知 :place cells
Nervous system Central nervous system (CNS) Brain ( 脑 ) Spinal cord ( 脊髓 ) Peripheral nervous system Cranial nerves ( 脑神经 ) Spinal nerves ( 脊神经 )
31 对脊神经 (Spinal nerves)
12 对脑神经 (Cranial nerves) 端脑 : 嗅神经 中脑 : 视神经 动眼神经 滑车神经 脑桥 : 三叉神经 展神经 面神经 前庭蜗神经 延髓 : 舌咽神经 迷走神经 副神经 舌下神经 一嗅二视三动眼, 四滑五叉六外展, 七面八听九舌咽, 迷走及副舌下全
Peripheral nervous system has somatic and autonomic divisions 躯体神经系统 : 包括感觉和运动, 其中运动神经可以通过意识加以控制 自主神经系统 : 包括交感和副交感神经系统 控制与调协内脏 血管 腺体等功能 因不受人意志支配, 故称自主神经, 也称植物神经 如果植物神经系统的平衡被打破, 那么便会出现各种各样的功能障碍 红色部分为交感神经, 蓝色部分为副交感神经
Functional Organization of Perception and Movement How input (perception) and output (movement) functions are realized in central nervous system
Somatosensory system 大脑 脑干 间脑中脑脑桥延髓 Medial lemniscus 内侧丘系 Functional systems on one side of the brain control the other side of the body 延髓 脊髓
Information processing in cerebral cortex Homunculus: illustrating the location and amount of cortical area dedicated to a particular function The area of cortex and the mass of the body part: not proportional! Hands, lips have larger representation Neurons are organized into a neural map of the body.
Information processing in cerebral cortex
Voluntary movement
Visual system To cortex: In cortex:
Auditory system Kamil Ugurbil, 2016