Neurophysiology  

 

 

1. Principles of neurophysiology The function of neurons Synaptic transmission

2. The functions of nervous system Sensory function Regulation of posture and movement Regulation of visceral function Advanced function

Part 1. The function of neuron and glial cell

1. Neuron :

(1) The types of neurons :Afferent, efferent, interneuron

dendrite Cell body

axon

terminal

Initial segment

Receiving part

AP

Conduction of AP

Transmitter release

(2) Classification of nerve fibers 

1) The conduction function of nerve fiber

Mechanisms of conduction

Local excitation

Properties of conduction in nerve fiber

intact, insulating, bi-directional, not easy to be fatigued

Conduction velocity

V (m/s)≈6☓Φ(μm),

Φ(axon): Φ(total)=0.6

Temperature

Classification of nerve fibers

Fiber types

FunctionAvg. fiber diameters

(μm)

Avg. cond. Velocity (m/

s)

Aα Primary muscle spindle afferents, motor to skeletal muscle

15100 (70-12

0)

Aβ Cutaneous touch and pressure afferents 8 50 (30-70)

Aγ motor to muscle spindle 5 20 (15-30)

Aδ Cutaneous temperature and pain afferents <3 15 (12-30)

B Sympathetic preganglionic 3 7 (3-15)

C Cutaneous pain afferents sympathetic postganglionic

1 1 (02-2)

Erlanger /Gasser classification of nerve fibers

Group FunctionAvg. fiber diameters

(μm)

Avg. cond. Velocity

(m/s)

IPrimary muscle spindle afferents and afferents from tendon organs 

1375 (70-12

0)

II Cutaneous mechanoreceptors 

9 55 (25-70)

III Deep pressure sensors in muscle 

3 11(10-25)

IV Unmyelinated pain fibers 1 1

Lloyd/Hunt classification of nerve fibers

（ 3 ） Axoplasmic transport

Anterograde (fast: 410mm/d, slow: 0.2-12 mm/d) Retrogerade: 205mm/d Rabies virus, poliomyelitis virus, tetanus toxin, horseeraldish peroxidase

Measurement of axoplasmic transport

Mechanism underlying axoplasmic transport

(4) Trophic action between nerve and tissue

Functional action Neurotrophic action: muscle atrophy after nerve injury

Trophic action on nerve nerve growth factor (NGF), brain-derived neurotrop

hic factor (BDNF), NT3 and NT-4/5 Receptors for neurotrophic factors

2.Glial cell

Part 2 Synaptic transmission There are 10 11 neurons in central nervous system. Each neuron make around 1000 synapses 1. Classical synaptic transmission

(1) Types and structure of synapse

(2) Process of synaptic transmission presynaptic ending → opening of voltage-gated Ca2+channel→ Ca2+ influx→release of transmitters → change of channels in postsynaptic membrane →postsynaptic potential → excitatory or inhibitory

(3) Excitation and inhibition of postsynaptic neurons

Excitatory postsynaptic potential (EPSP) and postsynaptic excitation

Release of excitatory transmitters in presynaptic fiber → p

ermeability of postsynaptic for Na+ 、 K+ （ especially Na+ ）↑→ EPSP → summation of EPSP reach to threshold → action potential at initial segment.

The density of voltage-gated sodium channels is 7 time higher in initial segment, so threshold is lower than cell body

EPSP and IPSP

Interneurons release inhibitory neurotransmitter opening of Cl channel in postsynaptic neurons EIPSP

Inhibitory postsynaptic potential (IPSP) and postsynaptic inhibition

Afferent collateral inhibition Recurrent inhibition

Postsynaptic inhibition

(4) Characteristics of synaptic trans- mission One way conduction Central delay, 0.3-0.5 ms through one

synapse Summation Susceptibility to environmental

changes and fatigue

（ 5 ） The patterns of neuronal connection

Divergence: the excitation of one neuron causes activation or inactivation of many neurons simultaneously.

Convergence: activity in one neuron is controlled by many functionally different neurons.

Chain connection: increases the area of influence.

Circuit connection: related to negative or positives feedback control.

(6) Modulation of synaptic transmission

Presynaptic inhibition

a. The structural base: axo-axonic synapse.

b. Release of neurotransmitter depends on the

amplitude of AP, which can be decreased

by axo-axonic synapse.

c. Presynaptic inhibition has long latency (20

ms to peak) and persists long period of time

(100-200 ms).

Inhibitory interneuron B releases GABA→ ① GABAA receptor in neuron A，permeability for Cl- outflow ↑ →depolarization of A→ AP↓，Ca2+ inflow↓ ② Activation of GABAB receptor →G-protein→ opening of voltage dependent K+ channels → K+ outflow ↑ and Ca2+

inflow↓ or directly close Ca2+channels →Ca2+ inflow↓→ release of transmitter in fiber A↓→ postsynaptic EPSP↓

Presynaptic facilitation Structural base：Axo-axonic synapse

Activation of interneuron B→ release of 5-HT→ close of K+ channel in fiber A→time course of AP↑ → Ca2+ inflow↑ →transmitter release in fiber A ↑ →postsynaptic EPSP↑

小结

一、EPSP与IPSP EPSP IPSP 1.突触前 兴奋性 抑制性中间 神经元 神经元 神经元 2.递质的性质 兴奋性递质 抑制性递质 3.突触后膜离子 Na+、K+，尤 Cl - ↑通透性 通透性的变化 其是Na+通透 ↑性 ———————————————————————

EPSP IPSP

4.突触后膜电位 去极化 超极化 变化 5.突触后神经元 增加 降低 兴奋性 6.在信息传递中 突触后神经 突触后神经 作用 元产生动作 元不容易产 电位或易化 生动作电位

二、突触前抑制与突触后抑制

突触后抑制 突触前抑制 结构 基础

抑制性中间 神经元

轴-轴型突触

产生 机制

突触后膜超 极化（IPSP）

突触前末梢释放的 ↓→兴奋性递质 突

触后膜 EPSP↓ 突触后膜兴奋性

↓ 不变

潜伏期 持续时间

较短 较短(10 ms)

较长 较长（100-200 ms）

突触后抑制 突触前抑制

影响范围

抑制突触后神经 元所有的兴奋性 信息传递

仅抑制某一传入 神经末梢的信息 传递

生理意义

调节传出神经元 活动。使神经元 活动及时终止或 促进同一中枢内 神经元活动协调

调节传入神经元 活动，选择性控 制传入的感觉信 息

2. Non-synaptic chemical transmission

no synapse no 1:1 relationship Varicosity and effector is not closely

together（>20μ m），need 1 s The effects of transmitters depend on

the type of postsynaptic receptors

3. Electrical synaptic transmission gap junction Characteristics：fast, bi-direction significance：synchronous discharges of

neurons.

4. Neurotransmitters and receptors (1) Neurotransmitter Identification of neurotransmitter

Synthesis in presynaptic neuron Stored in terminal and can be released

Binding to postsynaptic receptors Removed quickly after action Specific agonist and antagonist

         NeuromodulatorΚ NA δ NA

Classification of transmitter and modulator (table 10-4 ）          Dale’s principle          Motablism of neurotransmitter

(2) Receptor Concept Ligand: agonist, antagonist specific，saturation，reversible Classification and mechanisms

a. ion channel coupling receptor b. metabotropic receptor (G-protein coupled receptor)

• Presynaptic receptor

自身受体

异身受体

(3) The main transmitters and receptors Acetylcholine (Ach) and receptor

In 1921 Loewi discovered neurotransmitter in vagus, Noble price in 1936

Distribution in peripheral nervous system

Distribution in central nervous system a. Synapse between Renshaw `s cell and collaterals from motor neurons b. Synapse between neurons in cortex and the neurons of specific projecting system from ventral basal part of thalamus. c. Ascending activating system in reticular formation of the brain stem d. Corpus striatum e. Pyriformis, amygdala, hippocampus

Cholinergic receptor M (muscarine) isoform: M1～5

G-protein coupled receptor effect: heart ↓ ,constraction of smooth muscle in bronchus and in gastrointestinal tract, Detrusor muscle of urinary bladder, circular muscle in iris the excretion of digestive, sweat gland↑ blood vessles in skeletal muscle relax antagonist Atropine

N (nicotine) Muscle-type and Neuronal-type nicotinic receptor

Constraction of skeletal muscle excitation of autonomic ganglia cell curare

Catecholamine and receptor adrenaline (A), noradrenaline (NA) and dopamine ① Adrenergic fiber ： sympathetic postganglionic fiber ② Adrenergic neuron ： mainly in medulla ③ Noradrenergic neuron：mainly in low brain stem

adrenergic receptor receptor receptor isoform

1 2 1、 2、 3

agonist NA >A >ISO

ISO>A>NA

antagonist Phentolamine (酚妥拉明) 1：prazosin (哌唑嗪) 2：yohimbine (育亨宾)

Propranolol (普萘洛尔) 1：atenol (阿提洛尔) 2： butoxamine (丁氧胺)

Dopamine and receptor distribution： substantia nigra - neostriatum mesencephalon - limbic forebrain nod-choana

Receptor：D1 and D5 cAMP

D2,D3,D4 cAMP

Serotonin (5-hydroxytryptamine, 5-HT) distribution： raphi nucleus in the middle of lowere brain stem

Receptor：5-HT1～７receptor

Amino acid and receptor

Excitatory ： glutamate( 谷氨酸 ) ，

aspartic acid( 门冬氨酸 )

Inhibitory ： GABA (γ- 氨基丁酸 ) ， glycine( 甘氨酸 )

            a. Glu

  excitatory transmitter in cerebral cortex and sensory afferents

            receptor ：① ionotropic receptor ：

            KA ， AMPA ， NMDA

②metabotropic receptor

b. GABA

Inhibitory transmitter in cerebral cortex and cerebrum corpus striatum

Rece GABAA （ ionotropic rece

ptor ） permeability for Cl-↑

GABAB （ G-protein coup

led receptor ） :

permeability for K+↑and for Ca2+↓

c. Glycine (甘氨酸) Inhibitory transmitter in Renshaw cell of spinal cord but excitatory when combine with NMDA receptor Receptor（ionotropic ）：permeability for Cl-↑

Peptide and receptor

a. Piptide hormone in hypothalamus b. Opium： β -endorphin(内啡肽) μ enkaphalin(脑啡肽) δ dynorphin(强啡肽) κ

c. Braingut peptide (脑肠肽) d. Cholecystokinin (胆囊收缩素)

Purine and receptor Purinergic receptor

A1, A3 CAMP P1 A2A, A2B CAMP

P2Y,P2U G-protein, phospholipase C

P2

P2X (P2X1,P2X2,P2X3) P2Z

Other transmitters

① Histamin： located in hypothalamus ② NO ③ CO ④ Prostaglandin

Part 3 Sensory function of nervous system 1. Sensory conduction pathways （1） Primary afferent neurons （2） Spinal cord and brainstem touch-pressure, thermo-, nociception decussate

in spinal cord fine tactile sensation, proprioception decussate

in medulla oblongata

thalamus

Cuneate, gracile nucleus

DRG

Pain toutch pressure

lateral spinothalamic tract

Anterior spinothalamic medial lemniscus

Anterior spinothalamic tract

lateral spinothalamic tract

fine tactile sensation, proprioception

Specific relay nucleus

Two point threshold

Two point threshold

Contralateral trigeminal lemniscus

thermo-, nociception tactile proprioception

Head and face

spinal trigeminal nucleus Main trigeminal nucleus

Thalamus

(3) Thalamus

Specific sensory relay nuclei receive direct sensory projection, and then project to the specific area in cortex

Ventral posterior nucleus: lateral part receives medial lemniscus and spinothalamic tract and medial part receives trigeminal lemniscus

Lateral geniculate (LG) nucleus for visual afferent

Medial geniculate (MG) nucleus for auditory afferent

Associative nuclei receive projection from relay nuclei and subcortical center but not from sensory projection, and then project to the associative area in cortex. They participate in the integrative functions of brain.

Nonspecific projection nuclei (plate medial

nuclear group) receive affernts from spinoreticular tract and paleospinothalamic tract, and then project to all layers of cerebral cortex after polysynaptic relay. The system evokes no definite sensation but maintain the excitatory state of cerebral cortex.

(4) Sensory projection system specific nonspecific project area

specific area， point to point mainly in layer 4 axo-body synapse

wide area no point to point in every layer axo-dendrite synapse

Function Difinite sensation Keep cerebral cortex to be excitatory

Ascending reticular activating system(ARAS) 2. Sensory function of cerebral cortex (1) Somatosensory cortex

SI SII Postcentral gyrus The up wall of the

lateral sulcus Downright projection Upright projection Unilateral cross pro-jection but head and face

Bilateral projection

Size of the representative area is in proportion to the delicacy and sensitiveness of the sensation

Incomplete representation, less delicacy and sensitiveness

Sensory column

Diamter ： 0.3-0.5 mm, 10,000 neurons

Each sensory column responses to specific sensory form

Specific thalamus project to layer IV and nonspecific thalamus to layer I and II.

Neurons in layer II and IV connect horizontally with other neurons in the column

Neurons in layer V, VI send axons to other part of cortex, thalamus and spinal cord.

Neurons in layer II, III inhibit neurons in adjacent column.

3. Pain (1) Surface pain

● Pain receptors are free nerve endings. Any kind of stimuli when reaching to pain threshold can induce pain. Pain is mediated by chemicals, such as K+, H+, histamine and Bradykinin released by damaged tissues.

● Fast pain, a bright sharp pain, well definied sensation, quickly onset and quickly disappear, conducted by A afferent fibers.

● Slow pain, a dull, burning pain diffuse but not well defined, slowly onset and slowly disappear, conducted by C afferent fibers, usually with emotional and vegetative responses

(2) Viscreral pain and referred pain Visceral pain: slow, persistent, poorly

located, sensitive to stretching of hollow organs, ischemia, spasm, inflammation but not sensitive to cutting and burning.

Conducting pathway: afferent fibers via

sympathetic nerve and dorsal root go into spinal cord. The afferents from esophagus and trachea are vagus and afferents from pelvic organs are pelvic nerve.

The mechanism of referred pain a. Facilitation theory (易化学说) b. Convergence theory (会聚学说)

facilitation

convergence

(3) Modulation of pain

Gate control theory

Descending inhibitory pathways

(4) Pathological pain

Hyperalgesia, allodynia, spontaneous pain

Peripheral sensitization

Central sensitization

Part 4. Somatomotor function of nervous system

Reflexive movement

Rhythmic movement

Voluntary movement

Lower motor neuron

Upper motor neuron

1. Spinal control of locomotion (1) Motor neurons and motor unit In ventral horn of spinal there are

motor neurons that innervate extrafusal muscles , motor neurons that innervate intrafusal muscles and β motor neurons.

A motor unit is consisted of a single motor neuron and its innervated muscle fibers.

α motor neuron γ motor neuron

Size 30-150μ 10-30μ

Excitability Low High, spontaneous

Controlled High center Peripheral

High center

Effector Largeα ：fast muscle Smallα ：slow muscle

Intrafusal muscle fiber

Effect Muscle contraction Muscle spindle

(2) Stretch reflex When innervated muscle is stretched, it contracts. Tendon reflex (Phasic stretch reflex) is a monosynaptic

reflex. Muscle tonus (Tonic stretch reflex) elicited by the

continuous stretch and may be polysynaptic reflex. Its significance is maintenance of body’ s posture by producing muscle contraction continuously

The mechanism of stretch reflex a. Muscle spindle, composed of 6 to 12 intrafusal muscle

fibers, measures the length of muscle. b. Dynamic phase: during stretching dynamic nuclear

bag fibers are activated. The signals is conducted to spinal cord via primary afferents (Ia)

c. Static phase: during maintenance of muscle length static nuclear bag fiber and nuclear chain fiber are excited, the signal convey into spinal cord via secondary afferent (II)

d. Dynamic γ -motor fibers increase dynamic responses of Ia afferents while static γ -motor fibers enhance static responses of Ia and II responses.

e. The role of γ -motor neurons is maintenance of sensibility of muscle spindle during muscle contraction

    Reflex arc of stretch reflex

Inverse stretch reflex

Tendon organ embedded in the tendon at the end of the muscle measure the tension of muscles can be activated by isometric contraction of extrafusal fibers. Tendon organ is innervated by Ib afferent fibers, which synapses with inhibit

ory interneurons and inhibit α motor neurons .

(3) Flexor reflex and crossed extensor reflex

Flexor reflex induced by noxious

stimulation in spinal animals is a typical protective reflex.

Babinski` sign belongs to flexor reflex.

(4) Spinal shock A reversible motor and autonomic

areflexia following transection of spinal cord.

Associated with the loss of connection with high nervous center but not related to noxious stimuli by cutting

The time for recover varies in different species. The higher is the animal, the longer is the time.

2. Brain stem (1) Decerebrate rigidity

An exaggerated tone of the antigravity muscles induced by transection between midbrain and pons It is diminished or vanished altogether by transection of dorsal root.

(2) -rigidity and -rigidity -rigidity is induced by direct activation of -motoneurons by supralspinal motor center. -rigidity is initiated by activation of -motoneurons, which causes the contraction of intrafusal muscle fibers, and then activate receptors in muscle spindle, finally produces contraction of extrafusal fibers.

2 Postural regulation of brain stem Attitudinal reflex(状态反射) Tonic labyrinthine reflex(迷路紧张反射) Tonic neck reflex(颈紧张反射) Righting reflex(翻正反射)

3. Basal ganglia Basal ganglia include striatum (caudate nucleus, putamen, globus pallidus), subthalamus, substantia nigra are related to voluntary movement and muscle tone. Direct pathway facilitate wanted movement Indirect pathway inhibit unwanted one (1) Parkinson’ s disease may be resulted from the loss of

dopaminergic innervation from substantia nigra to the striatum.

(2) Huntington’ s Chorea may be caused by loss of GABAnergic and cholinergic neurons in striatum.

   

Middle part of posterior lobe

Sensory cortex

Motor cortex

Somatosensory input

Visual and auditory input

pontine nucleus

4. Cerebellum (1)  Vestibulocerebellum—flocculonodular lobe is related to the equilibrium of body and eye movement

(2) Spinocerebellum—anterior lobe and middle part of posterior lobe Muscle tone: Vermis inhibits muscle tone. Other part of anterior lobe facilitates muscle tone

Voluntary movement:

vestibulocerebellum

spinocerebellum

Cortico-cerebellum

spinal and trigeminal

Cortical, pons

Visual , auditory

vestibular

input output Interaction

betw cortex and cerebell

um

fastigial

interposed

dentate

(3) Corticocerebellum—lateral part of posterior lobe is associated with motor learning and performance of purposeful intricate movement.

5. Cerebral control of somatic movement In primates the area 4 and 6 in precentral gyrus are motor cortex. Cross innervation, except head and face,

majority of the muscles of head and face are controlled bilaterally.

The extent of the representative area is dependent on the delicacy and complexity of the muscle movements.

The motor cortex is organized as an inverse image of the body with leg on the top and the head on the bottom.

Part 5. Neuroregulaion of visceral activity Autonomic nervous system (1) Structural properties (2) The functions of autonomic nervous system Double innervation Tonic control Effects depends on the functional state Different physiological significance Sympathetic system is responsible for the rapid change in external environment and is involved in the stress and emotion. Parasympathetic system is more responsible for digestion, absorption and energy storage and is more active during recovery and at rest.

2. Central control of autonomic nervous system

(1) Spinal cord As sympathetic and partial parasympathetic preganglionic neurons is located in lateral horn of spinal cord, spinal cord is a primary center for visceral reflexes for micturition, defecation, vasoconstriction, sweating and so on. (2) Brain stem

In medulla oblongata, apart from the parasympathetic preganglionic neurons, there are also circulatory, respiratory centers.

(3) Hypothalamus Body temperature, set point Water intake, the area controlling drinking

is near in feeding center. Water excretion is regulated by antidiuretic hormone synthesized in the supraoptic nucleus and paraventricular nucleus and stored in neurohypophysis

Hormone of adnohypophsis

•Biorhythm

High frequency: cycle shorter than a day, such as breathing cycle

Middle frequency: circadian(diurnal)rhythm, may be controlled by suprechiasmatic nucleus (SCN)

Low frequency: cycle longer than a day , menstrual cycle

Feeding limbic forebrain septal area(隔区) amygdalae (杏仁核)

feeding center satiety center

hypothalamus

glucose in blood

Short-term signal and long-term signal

lateral region ventromedial nucleus

Regulation of emotion a. Defence zone in hypothalamus： Ventromedial area——defence Lateral area——fighting Dorsal area——flighting b. Limbic system： Dorsal part of central gray substance in midbrain——defence Lateral part of amygdalae——fear and flighting Medial and caudal part of amygdalae—fighting

Part 6. Advanced function of the brain 1. Learning and memory (1) The forms of learning Nonassociative learning a. Habituation is referred to a form of

accommodation to a repeated stimulus that is not harmful or unimportant to organism.

b. Sensitization is an increase in response to a

weak harmful stimulus following an intensive harmful stimulus.

Associative learning a. Classical conditioned reflex

stimuli reflex food （uncond.）— excretion of saliva（uncond.） sound（unrelated） — no excretion sound + food（reinforcement）— excretion sound（cond.）— excretion of saliva（cond.） b. Operant conditioned reflex5

(2) Principles of conditioned reflex Conditioned reflex can be established on the

bases of all unconditioned reflexes. The establishment of conditioned reflex is

related to the functional situation of animals Fading of conditioned reflex (CR), which

happens when conditioned stimulus is presented repetitively without unconditioned stimulus for consolidation, is not due to the loss of CR but due to the conversion of positive CR to negative CR.

Human beings have the first (different kinds of sensory stimuli) and the second (language) signal system.

(3) Classification of memory Declarative memory Non declarative memory (4) The process of learning and memory (5) Disturbances of memory Anterograde amnesia Retrograde amnesia

(6) Mechanisms of learning and memory

a. Functional location of memory

Hippocampal loop hippocampus (海马) fornix(穹窿)

mammillary body (乳头体)

cingulate gyrus anterior nucleus （扣带回） （丘脑前核）

b. Neuronal circles, hippocampal loop may be related to sensory memory and primary memory

c. Synaptic plasticity Post-tetanic potentiation, Presynaptic

Ca2+ accumulation → release of neurotransmitter↑

Habituation, Inactivation of presynaptic Ca2+ channel

Sensitization cAMP↑ → Ca2+ inflow↑

d. Long-term potentiation ， a fundamental mechanism of memory

Mechanisms underlying LTP

2. Speech center of cerebral cortex (1) Correlation of two hemispheres The commissural fibers in corpus callosum connect the two hemispheres (2) Speech and language areas Motor aphasia, The patient can understand

speech and text but cannot express his ideal by language and letter when his Broca region is damaged.

Sensory aphasia, loss of the ability to understand speech and text because of damage of Wernicke region.

Alexia, unable to read (V).

(3) Dominant hemisphere In general, in right-handers left hemisphere is dominant in speech and language and the right hemisphere is superior to the left in the respect of nonverbal identification, such as spatial, deep, touching, musical identification.

3. Bioelectricity of cerebral cortex (1) Evoked cortical potential

(2) Spontaneous electric activity of the brain

Electroencephalogram (EEG)

Wave Freq (Hz)

Amp (V)

Condition

0.5-3 20-200 Sleep only

4-7 100-150 Drowsiness

8-13 20-100 Awake, with eye closed

14-30 5-20 Awake with eye open

Mechanisms of EEG

The EEG essentially reflects the simultaneous postsynaptic activity of the cortical neurons.   rhythm is induced by thalamic nonspecific projecting system (thalamic pacemaker).

4. Waking and sleeping (1) The maintenance of awake state Ach from reticular formation of brain

stem for EEG waking Dopamine release from the subtantia

nigra for behavioral waking Noradrenalin from the locus coeruleus

(2) The phases of sleep 

  SWS REM

Arousal threshold Low High

Relaxation of skeletal muscle

Medial High

Vegetative function Low High,irregular

Rapid eye movement No Yes

EEG Synchronized slow wave

Unsynchronized rapid wave

Normal sleep alternates between SWS (80-120 min) and REM (20-30 min) for 4-5 times per night.

Both SWS and REM can be turned to waking state but waking state can only be turned to SWS.

Most dreams occur in the period of REM. Growth hormone secretion rate:

SWS>REM>waking state. During REM protein synthesis increases and

new synapses may be established.

Stages of slow wave sleep

(3) Mechanisms of sleep Sleep is an active process. There is an

ascending inhibitory system in caudal part of brain stem sending fibers to cortex, which act against the ascending activating system.

SWS may be related to 5-HT and REM

may be associated with both 5-HT and noradrenalin in brain stem.

腹侧被盖区伏核

扣带回

前额叶

Addiction

The circuit for addiction

Cutting the midbrain betw superior and inferior colliculus leads to decerebrate rigidity, an exaggerated tone of the antigravity muscles

Corpus striatum

superior colliculus cerebellum

Decerebrate rigidity is dimished by cutting dorsal root

Damage of anterior lobe of cerebellum , rigidity appear again

Removing vestibular apparatus by cutting auditory nerve (N. VIII), rigidity disappeared

表 10- 9 交感神经和副交感神经的主要功能

器官或系统 交感神经 副交感神经

循环系统 心跳加快加强；腹腔内脏血管、皮肤血管以及分布于唾液腺与外生殖器官的血管收缩，脾包囊收缩，肌肉血管可收缩（肾上腺素能纤维）或舒张（胆碱能纤维）

心跳减慢，心房收缩减弱；部分血管（如软脑膜动脉与分布于外生殖器的血管等）舒张

呼吸器官 支气管平滑肌舒张 支气管平滑肌收缩，粘膜腺分泌

消化器官 分泌粘稠唾液，抑制胃肠运动，促进括约肌收缩，抑制胆囊活动

分泌稀薄唾液，促进胃液、胰液分泌，促进胃肠运动和使括约肌舒张，促进胆囊收缩

泌 尿 生 殖 器官

促进肾近端小管和髓袢对 Na+ 和水重吸收，逼尿肌舒张和括约肌收缩；有孕子宫收缩，无孕子宫舒张

逼尿肌收缩和括约肌舒张

眼 虹膜辐射状肌收缩，瞳孔扩大；睫状体辐射状肌收缩，睫状体环增大；上眼睑平滑肌收缩

虹膜环行肌收缩，瞳孔缩小；睫状体环行肌收缩，睫状体环缩小；促进泪腺分泌

皮肤 竖毛肌收缩，汗腺分泌（胆碱能纤维）  

内分泌 促进肾上腺髓质分泌（节前纤维） 促进胰岛素分泌

代谢 促进糖原分解  

In 1861 Broca found that damage of inferior frontal gyrus on the left hemisphere leads to motor aphasia ( 运动性失语 )

In 1874 Wernicke found that damage of superior temporal gyrus on the left hemisphere leads to sensory aphasia ( 感觉性失语 )

Arcuate fasciculus

Wernicke-Geschwind Modle

Lateral corpora geniculata

angular gyrus Arcuate fasciculus

The density of voltage-gated sodium channels is 7 time higher in initial segment, so threshold is lower than cell body

GABAA

GABAB

5-HT

表 10-1 哺乳类动物外周神经纤维的类型（ Erlanger /Gasser 分类）纤维

类别功能 纤 维 直

径（ μm ）

传 导 速度(m/s)

锋 电 位 时程(ms)

绝 对 不 应期(ms)

Aα 肌梭传入、运动传出

12~20 70~120 0.4~0.5 0.4~1.0

Aβ 皮肤触压觉传入 5~12 30~70 0.4~0.5 0.4~1.0

Aγ 梭内肌的传出 3~6 15~30 0.4~0.5 0.4~1.0

Aδ 皮肤温痛觉和触觉传入

2~5 12~30 0.4~0.5 0.4~1.0

B 交感神经节前纤维 1~3 3~5 1.2 1.2

C 皮肤痛觉传入、交感神经节后纤维

0.3~1.3 0.5~2.0 2.0 2.0

  

表 10-2 传入神经纤维的分类（ Lloyd/Hunt 分类）

纤维类别 来源 直径（ μm ）

传 导 速度 (m/s)

电 生 理学分类

Ia 肌梭传入 12~22 70~120 Aα

Ib 腱器官传入 12 左右 70 左右 Aα

II 皮肤机械感受器传入（触 - 压、振动觉）

5~12 25~70 Aβ

III 皮肤痛、温度觉、肌肉的深部压觉传入

2~5 10~25 Aδ

IV 无髓的痛觉、温度、机械感受器传入

0.1~1.3 1 C

From spinothalamic, medial lemniscus

From trigeminal lemniscus visualauditory

mamillary body

Cingulate nucleus regulation of internal organs

VP, cerebellum, globus pallidus

Anterior N

Ventral posterior N

motor neuron: final comm

on pathway

Dynamic static

Length of muscle

Dynamic

Static

aplysia

Melzack and Wall 1965

Inhibitory interneuron

Projection neuron

+

periaqueductal gray

locus ceruleus

nucleus raphes magnus

Isotonic

Isometric

Direct p

athw

ay

Direct pathway facilitate wanted movement

Indirect pathway inhibit unwanted one

1817 James Parkinson described Paralysis agitans

excitability of DP

DA

excitability of IDP

Ventrolateral nucleus is related to static tremor

1872 George Huntington described Choreareticular part of SN

midlde part of globus pallidus

subthalamuscompact

part of SN

Lateral part of globus pallidus

Ind

irect path

way

Supraoptic nucleus

Paraventricular nucleus

Arcuate nucleus

4g/1400g

lateral ventricle

Feeding

Thalamus arcuate nucleus

Neuropeptide Y neurons

insulin Leptin from fat cell

Inputs from gastrointestinal tract

Paraventricular nucleus

Oxytoxinergic neurons

stress

nucleus of solitary tract

Area postrema