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1、Sensory Systems,LIJUN KANG INSTITUTE OF NEUROSCIENCE ZHEJIANG UNIVERSITY KANGLIJUNZJU.EDU.CN 2014.05.23,Aristotles five senses (plus the sixth sense equilibrium),听,视,味,嗅,触,Part I: The Chemical Senses Taste (gustation，味觉) Smell (olfaction，嗅觉),Chemical sensation is the oldest and most common of the se
2、nsory systems.,The Basic Tastes,poisonous substances are often bitter,酸甜咸苦鲜,Umami（鲜）, unfamiliar delicious taste,Kombu dashi,Glutamate: 谷氨酸 Inosinate:肌苷酸盐,次黄(嘌呤核)苷酸盐 Guanylate:鸟苷酸,Each food activates a different combination of basic tastes 2. Most foods have a distinctive flavor as a result of their
3、 taste and smell occurring simultaneously 3. Other sensory modalities may contribute to a unique food-tasting experience： Texture, temperature, pain sensitivity,Complex flavors,The Organs of Taste,Papillae: 乳头状突起 Foliate: 叶状的；层状的 Vallate:杯状的 Fungiform：菌状的 Taste buds: 味蕾 Basal cell：基底细胞 Taste cell：味觉
4、细胞 Gustatory afferent axon： 味觉传入轴突 Synapse：突触 Microvillus：微绒毛；微小突起物,The myth of the tongue map,Hnig, David (1901). “Zur Psychophysik des Geschmackssinnes“. Philosophische Studien 17: 576623.,酸甜咸苦鲜,Taste Map？No!,cranial nerves: 脑神经,Taste Map？No!,Columbia University,Charles Zuker,Taste receptor cells
5、1. Not neurons 2. Form synapses with the endings of gustatory afferent axons near the bottom of the taste bud,Taste Receptor Cells,Mechanisms of Taste Transduction,Taste stimuli, or tastants, may Directly pass through ion channels (salt and sour), bind to and block ion channels (sour), bind to G-pro
6、tein-coupled receptors in the membrane that activate second messenger systems that, in turn, open ion channels (bitter, sweet, and umami).,GPCR,Ion Channel,Encoding of taste qualities at the periphery,Central Taste Pathways,Taste Buds (味蕾) Taste Receptor Cells Cranial nerve (脑神经) Medulla（脊髓）Gustator
7、y Nucleus Ventral posterior medial nucleus of thalamus(丘脑腹后内侧核) Gustatory cortex (味觉皮层）,Smell Olfaction,As many as 100,000 unique odors can be discriminated a. 80% of which are noxious b. Odors perceived to be noxious are often deleterious (rotting meat, etc.).,The Organs of Smell We do not smell wi
8、th our nose. Rather, we smell with a small, thin sheet of cells high up in the nasal cavity called the olfactory epithelium (嗅上皮),The location and structure of the olfactory epithelium.,Cribriform 筛状板 Olfactory Bulb 嗅球,Cribriform 筛状板,Olfactory Bulb 嗅球,Olfactory Epithelium 嗅上皮,Size of the olfactory e
9、pithelium is proportionate to olfactory acuity i. Man has 10 cm2 ii. Dog has 170 cm2 iii. Dogs also have 100x receptors per cm2,Olfactory Receptor Neurons,Voltage recordings from an olfactory receptor cell during stimulation,Transduction mechanisms of vertebrate olfactory receptor cells,Odor GPCR AC
10、 cAMP CNG Channel CLC Channel,Transduction mechanisms of vertebrate olfactory receptor cells,1. Only receptor discussed thus far that are neurons a. Fire action potentials b. Only neurons in the nervous system that are replaced regularly throughout life Every 4-8 weeks 2. Olfactory receptors are neu
11、rons and continuous with the CNS 3. Ends of the olfactory receptors are mucus（粘液） (water soluble) containing cells of the immune system and is shed every ten minutes 1) Individual with an infection (cold, flu, etc.) one sympton is a runny noise 2) Mucus is shed more frequently to protect the olfacto
12、ry receptors from infection 4. 500-1000 different odor binding proteins Each olfactory receptor cell expresses only one type of binding protein 5. Receptor is G-protein-coupled,Olfactory Receptor Neurons,Central Olfactory Pathways,Glomerulus 嗅小球,Central Olfactory Pathways,Central Olfactory Pathways,
13、Olfactory Tract: 嗅束 Olfactory Cortex：嗅皮层 Thalamus Medial Dorsal Nucleus: 丘脑背内侧核 Orbitofrontal Cortex: 眶额皮层,Part II： The Auditory Systems,THE STRUCTURE OF THE AUDITORY SYSTEM,Anatomy of the Cochlea,耳蜗的三个管腔（前庭阶、中阶和鼓阶）,Cochlea Hair Cells,Piotr Kazmierczak (Trends in Neurosciences, 2012),Hair cells and
14、their mechanotransduction machinery,Depolarization of a hair cell,Tip-Link,Sensory TRPs (Transient Receptor Channel),Part III: The Somatic Sensory System,Somatic sensation enables our body to feel, to ache, to chill, and to know what its parts are doing,Touch Pain Temperature ,Sensation of touch,Rec
15、eptive Field 感受野,Mechanoreceptors of the Skin,Molecules that govern touch sensitivity in mammalian somatosensory neurons,Touch-sensitive axons in the spinal cord,背根节神经元,dorsal root ganglion cell （DRG cell）,背柱-内侧丘系,The dorsal columnmedial lemniscal pathway,The Sensory Homunculus is an image that show
16、s the relative amount of cerebral cortex surface area given over to processing the different sensory inputs and motor outputs of human nervous system,Sensory Homunculus,PAIN,Pain is the feeling, or the perception, of irritating, sore, stinging, aching, throbbing, miserable, or unbearable sensations arising from a part of the body. Nociception (痛觉) is the sensory process that provides the signals that trigger pain.,mechanical nociceptors, selective responses to strong
