单选题：
1.在眼球的结构中，下列哪一个相当于照相机的镜头？【A】
A.晶状体 B.视网膜 C.玻璃体 D.虹膜
2. 29岁，女性，十个月前起病，言语错乱，别人难以理解，骂人毁物，逐渐言语活动减少，不能与周围人沟通，近三个月来呆坐少语，自笑，认为自己的事别人都能知晓，有人要害自己。查：意识清晰，目光表情呆滞，耳边有命令性幻听，被害妄想，被洞悉感，有思维中断，躯体及神经系统检查未见著征，该患者诊断为【B】 A、抑郁症 B、精神分裂症 C、脑肿瘤所致精神障碍 D、内分泌疾病所致精神障碍 E、偏执性精神障碍 3. 精神分裂症的发病属于
A．常染色体显性遗传病 B．常染色体隐性遗传病 C．染色体病 D．多基因遗传病 E．体细胞遗传病 是非题：
1.精神分裂症发病的因素有线粒体异常.
2.精神分裂症患病者人数比例大约占世界总人口的0.1%。 论述题：
问题1：何谓近视眼？如何矫正？What is myopia, and how is it corrected? Answer: Myopia, or nearsightedness, occurs when the eyeball is too long. 当眼轴过长时，就会产生近视。
Parallel rays from a distant light source, which are bent by the cornea and the lens, normally converge at exactly the same plane as the retina.
远处的平行光线通过角膜和晶状体的折射在视网膜上形成清晰地像。 When the eyeball is too long, the rays of light converge and cross before the retina.
但是当眼轴过长时，折射的光线就不能汇聚到视网膜上，而是在视网膜之前。 As a result, the image on the retina is a blurred circle rather than a point. 所以，这时候投射到视网膜的像是一个模糊的光圈而不是一个清晰的点。
This occurs because the amount of refraction that the cornea and the lens provide is too large to focus distant objects on the retina.
这是因为，通过角膜和晶状体折射作用太强了以至于不能把远处的物体投射到视网膜上。
To see distant points clearly, nearsighted people must use artificial concave lenses that help focus the image on the retina.
如果近视眼的人想要清楚的看到远处的物体，就需要佩戴凹透镜来帮助矫正。 问题2：当你“对黑暗产生适应”时，视网膜发生什么变化？你在黑暗里为什么看不见颜色？What happens in the retina when you “get used to the dark”? Why can’t you see color at night?
Answer: Getting used to the dark is called dark adaptation. 暗适应就是我们所谓的“对黑暗产生适应”。
This capability is a consequence of a duplex retina, in which cones function best at high levels of illumination and rods function best at low levels of illumination. 之所以有这种能力是因为，视网膜含有两种细胞：视锥细胞在主要强光下发挥作用，视杆细胞主要在弱光下发挥作用。
When moving from high to low levels of illumination, the
retina must be adapted to the dark before the rods are maximally sensitive.
当人从明亮的地方走到黑暗的地方，我们的视网膜就需要等待视杆细胞完全投入工作状态才能发回它的敏感性，这段时间就是适应。
Dark adaptation is a biochemical process in which rhodopsin, the rod photopigment, regenerates after being bleached in the light.
暗适应是一个生物化学的过程，视杆细胞的感光物质—视紫红质，在强光照射后重新合成。
The functional circuitry of the retina also readjusts as rhodopsin
regenerates. Consequently, information from more rods is available to ganglion cells. 视网膜的这种功能性的环路也会在视紫红质重新合成的时候进行调节。所以视杆细胞在感受光之后，就会把信息传给双极细胞。
The regeneration of unbleached rhodopsin and the resulting changes in functional circuitry take about 20-25 minutes.
视紫红质的重新合成以致发挥作用要20-30分钟。
At night, it is difficult to detect colors because the cones, which have three photopigments with different spectral sensitivities, are inactive.
在晚上，我们之所以分辨不出颜色是因为视锥细胞此时没有激活。它含有对三种
不同光谱敏感的感光物质。
Only cones are capable of color vision. 只有感光细胞是有色觉的。
At low levels of illumination, only rods are active and they contain only one photopigment.
在弱光下，只有视杆细胞是被激活的，但是他只有一种感光物质。 Rhodopsin’s peak sensitivity is 500 nm.
对视紫红质来说，最敏感的光波峰值时500 纳米。
问题3：神经性耳聋和传导性耳聋有何不同？What is the difference between nerve deafness and conduction deafness?
Answer: Nerve deafness is caused by the loss of neurons in the auditory nerve or the loss of hair cells in the cochlea.
神经性耳聋是由于听神经的神经元或是耳蜗神经的毛细胞的缺失造成的。 Tumors affecting the inner ear and specific drugs, such as quinine and some antibiotics, may cause nerve deafness.
当肿瘤侵袭内耳，或者使用一些药物，如奎宁和一些抗生素，就会导致神经性耳聋。
Explosions and loud music can also cause nerve deafness. 巨大的爆炸声响或是音乐也会导致神经性耳聋。
A disturbance of sound from the outer ear to the cochlea causes conduction deafness.
从外耳向耳蜗传导出现问题就会导致传导性耳聋。
This deficit may be due to simple problems, such as excessive wax in the ear, or serious problems, such as rupture of the tympanic membrane or pathology of the ossicles.
这个缺陷有可能是一些简单的问题，比如耳道里多余的耵聍。或是严重个问题，比如骨膜的破裂或是听小骨的病变。
问题4：试想像一个半规管有两种运动方式：围绕着其轴作旋转或作平行滑行。
在这两种情况下，毛细胞的反应个如何？为什么？Imagine a semicircular canal rotating in two different ways, around its axis — like a rolling coin, or
end-over-end — like a flipped coin. How well would its hair cells respond in each case, and why?
Answer: When the semicircular canal rotates around its axis, the wall of the
semicircular canal and the cupula begins to spin but the endolymph remains behind because of inertia.
一个半规管围绕着其轴作旋转时，半规管的壁和壶腹帽都开始旋转，但是内耳淋巴由于惰性作用保持不变。
The endolymph exerts force on the cupula. 所以内耳淋巴与壶腹帽就产生了相对运动。 The cupula bows, which bends the cilia. 壶腹帽弯曲牵拉毛细胞的纤毛。
This bending either excites or inhibits the release of neurotransmitters from the hair cells on to the vestibular nerve axons, depending on the direction of rotation. 这个弯曲既可以使毛细胞兴奋也可以使其抑制对前庭神经轴突的递质释放，这取决于旋转的方向。
When the semicircular canal is flipped end-over-end, the hair cells do not bend right or left and do not respond as a result.
当半规管做平行运动时，毛细胞并无左右弯曲，所以就不会有相应的反应。 However, this type of motion corresponds to rotation around the axis of another semicircular canal, which would register the movement for the vestibular system. 然而，这种运动的方式相当于另一个半规管的绕轴运动，这会反映在前庭系统上。
思考题：
Question 1: Give three reasons explaining why visual acuity(视敏度) is best when images fall on the fovea（视小凹）.( 给出影像落在视小凹中时视觉灵敏度最好的三个理由)
Answer: Visual acuity is best when images fall on the fovea for three reasons: 1) Visual acuity improves as the ratio of photoreceptors to ganglion cells decreases（视神经节减少）. Relatively few photoreceptors feed each ganglion cell in the fovea, resulting in a low ratio, which maximizes visual acuity.
2) The fovea sits in a pit that the lateral displacement of the ganglion and bipolar cells creates above the photoreceptors. This allows light to strike the photoreceptors without passing through the other layers of retinal cells, minimizing light scatter that can blur the image
. 3) Visual space is not mapped to the targets of visual input uniformly. The central few degrees of the retina are over-represented in “neural space.” Signals from
individual cones in the fovea are represented in a larger volume of brain tissue than input from photoreceptors in peripheral regions of the retina. This specialization contributes to high acuity in central vision.
Question 2: In what way is retinal output not a faithful reproduction of the visual
image falling on the retina?
Answer: The eye functions like a camera, but the retina does not function like the film. The retina is a part of the brain. The physical arrangement of photoreceptors and the interconnections among all the retinal neurons represent the beginning of visual information
Question 3: Following a bicycle accident, you are disturbed to find that you are
unable to see anything in the left visual field. Where has the retinofugal pathway been damaged?
Answer: Lesions anywhere in the retinofugal projection from the eye to the lateral geniculate nucleus (LGN) to the visual cortex may cause specific visual deficits depending on the site of the lesion. The bicycle accident has resulted in a transection of the right optic tract, resulting in blindness in the left visual field as viewed through either eye. Axons from the nasal retina of the left eye and temporal retinal of the right eye have been damaged. In contrast, a transaction of the right optic nerve would render a person blind in the right eye because both nasal and temporal axons
originating from the right eye would be damaged; none of the axons in the optic nerve have crossed to the opposite side of the brain. Crossing, or decussation, occurs at the optic chiasm, which lies between the optic nerve and the optic tract. Question 4: What part of the visual field is represented in the left LGN?
Answer: The left LGN receives retinal information about the right visual field. Left LGN neurons receive synaptic input from the retinal ganglion cells in the nasal half of the right retina and the temporal half of the left retina. In the left LGN, the left eye (ipsilateral) axons synapse on cells in layers 2, 3, and 5 and the right (contralateral) eye axons synapse on cells in layers 1, 4, and 6.
Question5: A worm has eaten part of one lateral geniculate nucleus. You can no longer perceive color in the right visual field of the right eye. What layer(s) of which LGN is damaged?
Answer: The worm has eaten koniocellular neurons in the left LGN, and perhaps some parvocellular neurons receiving contralateral retinal projections. In addition to neurons in the six principal layers of the LGN (layers 1–6), there are numerous tiny neurons on the ventral side of each of the six principle layers called koniocellular layers. The cells in the koniocellular layers receive inputs from the nonM-nonP types of retinal ganglion cells and have center-surround receptive fields that are either light-dark or color-opponent. If you cannot perceive color in the right visual field, it means that the color-opponent koniocellular layers of the left LGN are damaged. Some parvocellular neurons also exhibit color opponency.
Question 6: List the chain of connections that link a cone in the retina to a blob cell in striate cortex.
Answer: There are three parallel pathways: magnocellular, parvocellular, and
koniocellular that connect the retina to the striate cortex, but only the parvocellular and koniocellular pathways receive input from cones and are sensitive to differences in wavelength. The parvocellular pathway begins with P-type ganglion cells of the retina that project axons to the parvocellular layers of the LGN; these LGN neurons project to layer IVCof the striate cortex, which in turn project to blob neurons. The koniocellular pathway begins with nonM-nonP ganglion cells. These ganglion cells project axons to the koniocellular layers in the LGN that, in turn, project to the blob neurons in layers II and III of striate cortex.
Question 7: If a child is born cross-eyed and the condition is not corrected before the age of 10, binocular depth perception will be lost forever. This is explained by a modification in the circuitry of the visual system. Based on your knowledge of the central visual system, where do you think the circuitry is modified?
Answer: The noncorresponding input from the two, misaligned eyes prevents the formation of binocular neurons in striate cortex or any extrastriate visual area. Question 8： In what ways is area MT more specialized for the detection of visual motion than area V1?
Answer: Neurons in area MT have large receptive fields that respond to stimulus
movement in a narrow range of directions. Almost all cells are direction-selective, and many respond to specific types of motion, such as drifting spots of light. The organization of area MT reveals a specialization for motion
processing—direction-of-motion columns that are analogous to the orientation
columns in area V1. The direction-of-motion columns facilitate a comparison of the activity across columns spanning a range of 360o of preferred directions.
Question 9: For many years, it was thought that depth perception involved the
recognition of objects in each eye separately followed by binocular integration. How do the stereograms discussed in Box 10.4 disprove this hypothesis? What areas of the brain are possible sites for binocular integration?
Answer: The stereograms are created by two sets of randomly spaced dots. Some of the dots shown to one eye (such as those within a smaller square) are shifted
horizontally relative to the dots shown to the other eye. The visual system interprets this shift as a difference in the vantage points for the two eyes, so the resulting image is seen in three dimensions. This would not be possible if it was necessary to first perceive the square and then perceive it in three-dimensional depth. Potential sites of binocular interaction include the superficial layers of the striate cortex and the extrastriate visual areas to which they project.
Question 10: Why is the round window crucial for the function of the cochlea? What would happen to hearing if it suddenly didn’t exist?
Answer: The round window is a membrane located at the base of the cochlea. When the ossicles move the membrane that covers the oval window, the inward movement at the oval window pushes the perilymph into the scala vestibuli. This increases the
fluid pressure on the oval window, pushing the membrane at the round window outward. A complementary motion at the round window accompanies any motion at the oval window. This movement is crucial because the cochlea is filled with
incompressible fluid held in a solid bony container. If it were absent, the fluid in the cochlea would not move in response to pressure at the oval window and the auditory receptors would not be stimulated.
Question 11: Why would the transduction process in hair cells fail if the stereocilia as well as the hair cell bodies were surrounded by perilymph?
Answer: Endolymph, which is similar to intracellular fluid, surrounds stereocilia and hair cell bodies. It has a high K+ concentration and a low Na+ concentration. The high K+ concentration is responsible for a K+ equilibrium potential of 0 mV. As a result, when K+ channels open, hair cells depolarize, moving toward the equilibrium potential of K+, which is 0 mV. In contrast, neurons, which have a K+ equilibrium potential of –80 mV, hyperpolarize when K+ channels open. Perilymph has an ionic concentration similar to CSF, which is low K+ and high Na+. If perilymph surrounds the stereocilia and hair cell bodies, hair cells will not depolarize when K+ channels open.
Question 12: If inner hair cells are primarily responsible for hearing, what is the function of outer hair cells?
Answer: Outer hair cells amplify the movement of the basilar membrane during low-intensity sound stimuli. They are cochlear amplifiers. The key to this function is the action of motor proteins in the membranes of outer hair cells. The motor proteins change the lengths of the outer hair cells. This changes the physical relationship between cochlear membranes, which causes the stereocilia on the inner hair cells to bend more, increasing the transduction process and producing a greater response in the auditory nerve. This mechanism causes about a 100- fold increase in the peak movement of the basilar membrane.
Question 13: Why doesn’t unilateral damage to the inferior colliculus or MGN lead to deafness in the ear?
Answer: Each auditory nerve projects to the dorsal and ventral cochlear nuclei on the ipsilateral side, so cochlear neurons listen to only one ear. On the other hand, cells in the ventral cochlear nucleus project to the superior olive on both sides of the brain stem. As a result, olivary neurons hear from both ears. The first binaural neurons in the auditory pathway are found at the level of the superior olive. This is in contrast to the visual system, where the first binocular neurons are found in the visual cortex of the occipital lobe. Binaural olivary neurons project to the inferior colliculus, which projects to the medial geniculate, so each structure hears from both ears. Because of the early convergence of input from both ears, only the destruction of cochlear nuclei can cause unilateral deafness.
Question 14: What mechanisms function to localize sound in the horizontal and vertical planes?
Answer: Horizontal sound localization results from two mechanisms: interaural time delay and interaural intensity difference. For example, if the sound source is on the right, sound reaches the right ear sooner than it reaches the left ear. Specialized neurons in the brain stem detect this interaural delay. Comparing continuous tones localizes them when the same phase of the sound wave reaches each ear. The second mechanism, interaural intensity difference, localizes high, continuous frequencies of 2,000-20,000 Hz. The head casts a sound shadow that alters the intensity of sound in each ear, depending on its origin. The resulting difference in sound intensity localizes sound. Neurons in the superior olive are sensitive to interaural delays. Vertical
localization depends on the sweeping curves of the outer ear, which are essential for assessing the elevation of a source of sound. Bumps and ridges produce reflections of entering sound, and the delays between the direct path and the reflected path change as a sound source moves vertically. The combination of direct and reflected sound is different for different elevations. High-frequency sounds also enter the auditory canal more effectively when they come from an elevated source.
Question 15: What symptoms would you expect to see in a person who had recently had a stroke affecting A1 unilaterally? How does the severity of these symptoms compare with the effects of a unilateral stroke involving V1?
Answer: Lesions of the auditory cortex are less severe than lesions of the visual cortex. The main symptom of a stroke affecting the A1 unilaterally is the inability to localize the source of a sound. It is possible to detect the side from which the sound is coming but not its precise location. In contrast, a unilateral lesion of the visual cortex
produces complete blindness in the part of the visual field corresponding to the site of the lesion.
Question 16: What is the difference between nerve deafness and conduction deafness? Answer: Nerve deafness is caused by the loss of neurons in the auditory nerve or the loss of hair cells in the cochlea. Tumors affecting the inner ear and specific drugs, such as quinine and some antibiotics, may cause nerve deafness. Explosions and loud music can also cause nerve deafness. A disturbance of sound from the outer ear to the cochlea causes conduction deafness. This deficit may be due to simple problems, such as excessive wax in the ear, or serious problems, such as rupture of the tympanic membrane or pathology of the ossicles.
Question 17: Each macula contains hair cells with kinocilia arranged in all directions. What is the advantage of this as compared to an arrangement with all cells in the same direction?
Answer: Each macula contains enough hair cells to cover a full range of directions. The direction preferences of hair cells vary in a systematic way. When the head moves, the mirror image orientation of the saccule and utricle on either side of the head excites some hair cells, inhibits others, and has no effect on the rest. The central nervous system can clearly interpret all possible linear movement. If the arrangement of hair cells is in the same direction, a slight movement of the head may excite all hair
cells.
Question 18: Imagine a semicircular canal rotating in two different ways, around its axis — like a rolling coin, or end-over-end — like a flipped coin. How well would its hair cells respond in each case, and why?
Answer: When the semicircular canal rotates around its axis, the wall of the
semicircular canal and the cupula begins to spin but the endolymph remains behind because of inertia. The endolymph exerts force on the cupula. The cupula bows, which bends the cilia. This bending either excites or inhibits the release of
neurotransmitters from the hair cells on to the vestibular nerve axons, depending on the direction of rotation. When the semicircular canal is flipped end-over-end, the hair cells do not bend right or left and do not respond as a result. However, this type of motion corresponds to rotation around the axis of another semicircular canal, which would register the movement for the vestibular system.
Question 19: How would you expect the functions of otolith organs and semicircular canals to change in the weightless environment of space?
Answer: Otolith organs detect the force of gravity and the tilt of the head. Semicircular canals are sensitive to the rotation of the head. In the weightless
environment of space, the lack of gravity might hinder the functioning of the otolith organs that help detect the force of gravity.
Question 20: What are the main hypotheses for molecular pathology of schizophrenia?
Question 21:What drugs induce mainly the positive symptoms of schizophrenia? What drug can induce both positive and negative symptoms?
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