Chapter 22 64. One important developmental question which is almost unique to the nervous system is: a. what factors determine the final shape of the main organs of the system? b. what determines the timing of the development of one part relative to another? c. what determines species differences in structure? *d. what factors determine the connectivity between one element (neuron) of the system and another? 65. Five events during the life cycle of individual neurons help shape the development of an adult nervous system. These events are genesis, _____, formation of connections and death. a. birth, migration b. migration, growth c. differentiation, growth *d. migration, differentiation 66. Among the events in the lives of neurons that help establish a functioning adult nervous system are a. genesis (birth), migration and stasis. b. differentiation, formation of synapses and reorganization. *c. migration, differentiation and death. d. genesis (birth), stasis and death. .pn 12 67. The development of any nervous system occurs as a consequence of the _____ _____ _____ _____ and death, in that order, of neurons. a. migration, growth, differentiation, formation of connections *b. genesis, migration, differentiation, formation of connections c. genesis, differentiation, migration, growth d. formation of connections, differentiation, growth, migration 68. The migration of developing neurons occurs mainly in a. invertebrate ganglia. b. vertebrate spinal cords. *c. vertebrate brain regions that are arranged in lamina. d. invertebrate sense organs. 69. Injection of tritiated thymidine into a mammalian fetus allows one to determine at what time particular neurons differentiate, because *a. thymidine has a short half-life in cells unless it is incorporated into DNA, which happens only in dividing cells. b. the thymidine can be detected by a monoclonal antibody later in life. c. the thymidine can be localized by specific histochemical techniques later in life. d. thymidine will be picked up by all cells except the dividing ones, therefore allowing the latter to be identified. 70. The inside-out development of laminar cell layers in rat cortex is an example of: a. overproliferation and cell death. b. neuronal locus specificity. c. the chemoaffinity theory of neural development. *d. none of the above. 71. In the developing rat cortex, laminar structure is: a. generated so that the oldest cells are farthest from the germinal layer. *b. developed in an inside-out fashion, so that the oldest cells are nearest the germinal layer. c. generated by the production of cells from two germinal layers, so that the oldest cells cannot readily be determined. d. none of the above. 72. The development of layers of cells in rat cerebral cortex is called ____ß development. a. laminar b. backwards c. upside down *d. inside out 73. Developing neurons in an insect ganglion will *a. tend to stay where they first differentiate, and NOT form laminar structures. b. tend to stay where they first differentiate, and then form laminar structures. c. tend to migrate from where they first differentiate, but NOT form laminar structures. d. tend to migrate from where they first differentiate, and then form laminar structures. 74. The generation of many more neurons than ever survive into adulthood in the developing vertebrate CNS might a. be manifested in a continued high death rate of neurons throughout life. b. be due to the influence of overlapping spatial and temporal gradients of development affecting certain regions. *c. lead to a competition among neurons for the formation of proper synaptic connections, thereby helping to ensure that a sufficient number of good contacts are made. d. be considered a manifestation of neuronal phenotypic specificity. 75. The initial direction of growth of an axon is always in a particular direction because a. the growth cone is inhibited by the cell's external environment from starting out in the wrong direction. b. Nerve Growth Factor only affects a specific region of the cell membrane. c. there are spatial gradients in developing tissues that orient the axonal bud. *d. none of the above. 76. A growth cone is a. the tip of a growing peripheral nerve bundle. b. the projection from the soma from which an axon starts to grow. c. the structure formed by an aggregation of cone-like pyramidal cells. *d. the slight swelling at the tip of a growing axon. 77. A growth cone is a. the conical junction between the soma and axon in a vertebrate neuron, formed by growth of the axon. b. a newly differentiated cone receptor in a vertebrate retina. c. the cone-like growth of a bundle of axons toward the central nervous system in insects. *d. the tip of a growing axon. 78. The person who proposed the chemoaffinity theory of neuronal development was a. Kandel. b. Roeder. *c. Sperry. d. Truman. 79. Roger Sperry has contributed important work in the field of a. neuroethology. *b. neural development. c. neuroendocrinology. d. neural basis of simple learning. 80. Sperry a. demonstrated the presence of guidepost cells. b. showed that pioneer neurons were responsible for guiding the proper path of growth of sensory axons in insects. *c. first proposed the chemoaffinity theory of neural development. d. showed that axons in a developing insect nervous system could express specific proteins. 81. Cutting the optic nerve of a frog and rotating the eyeball 180›ø degrees results in a. growth of the ganglion cell axons back to new, reversed positions in the optic tectum, so the frog sees the world RIGHTSIDE UP through the rotated eye. b. regrowth of the ganglion cell axons back to their original positions in the optic tectum, so the frog sees the world RIGHTSIDE UP through the rotated eye. c. growth of the ganglion cell axons back to new, reversed positions in the optic tectum, so the frog sees the world UPSIDE DOWN through the rotated eye. *d. regrowth of the ganglion cell axons back to their original positions in the optic tectum, so the frog sees the world UPSIDE DOWN through the rotated eye. 82. If one severs the optic nerve of the eye of a toad and rotates the eye 180›ø the animal behaves as if its visual world is upside down after a new optic nerve regenerates. This suggests a. the optic tectum is topographically organized. b. little processing of visual in formation is done in the toad's retina. *c. regenerating ganglion cells in the retina tend to make the same tectal connections they had before the eye was rotated. d. none of the above. 83. If the optic nerve of one eye of a toad is sectioned, and the eyeball simultaneously rotated in its socket 180 degrees, then after regeneration of the nerve, the toad acts as if the visual field of the operated eye is a. normal. *b. upside down and right-left reversed. c. upside down but not right-left reversed. d. rightside up but right-left reversed. 84. The idea that the nervous system establishes the central connections of peripheral neurons by a process of highly selective associations between neurons was supported by experiments in which a. growth of peripheral neurons was shown to be guided by pioneer neurons. b. monoclonal antibodies were used show the presence of specific proteins on neurons. c. motor neurons reinnervated their appropriate muscles after being cut. *d. the regenerating axons of a cut and rotated amphibian eye grew back to remake synapses at their original synaptic locations in the tectum. 85. The idea of developing connectivity between central neurons through use meant that a. neurons formed proper synaptic connections, then maintained them by using them. b. random synaptic connections were formed between many different neurons, but only the "proper" ones were usable. *c. random synaptic connections were formed between many different neurons, and the "proper" ones were picked out and maintained through a process of trial and error. d. only certain nonrandom synaptic connections were formed, but if they were not correct for a particular behavior, they were replaced by the correct ones. 86. Neural specificity during development refers to the idea that a. specific types of neurons become associated with each specific sensory modality. b. specific neural connections in the CNS are formed as a consequence of trial and error. *c. each neuron forms specific connections with those other neurons which are necessary for it to communicate with to form functional neural circuits. d. specific types of developing neurons grown into sensory neurons motor neurons or interneurons. 87. The hypothesis of neural specificity states that a. only certain interneurons are able to synapse with and therefore drive any specific motor neuron. b. learning can take place only at certain specific synapses in a nervous system. *c. during development, specific neurons will be able to locate and synapse with other specific neurons or with motor neurons. d. individual, specific neurons in a nervous system may be structurally and physiologically unique and identifiable. .pn 17 (No £88-95) 96. Electrical field and mechanical factor theories attempt to explain *a. how developing neurons are able to identify the direction in which their proper target cells lie. b. the growth of the nervous system. c. how severed optic nerve fibers are able to make proper reconnections with the optic tectum in Xenopus and salamanders. d. the formation of synapses between neurons. 97. Electrical field and mechanical factor theories of neural development attempt to explain a. how neurons decide in which direction to BEGIN growing. *b. how neurons are able to identify the direction in which their proper target cells lie. c. how neurons select one neuron out of a population with which to make synaptic contact. d. none of the above. 98. A guidepost cell is a cell that a. is the first sensory cell to start growing in from the periphery in an insect. *b. acts as a marker for developing sensory neurons in limbs of insects so the neurons can find their way to the CNS. c. releases chemical signals that repel growing neurons from some distance away so they will keep away from the wrong direction. d. does none of the above. 99. In a developing locust leg, pioneer neurons are cells that *a. just happen to start growing toward the CNS before similar, nearby cells, and therefore act as pathfinders. b. act as markers for turning points for the neurons that search for them. c. are genetically programmed to start growing centrally first, and therefore are the only cells that can act as pathfinders. d. just happen to start growing out of the CNS before similar, nearby cells, and thereby act as pathfinders. 100. If a cell used as a marker by a pathfinding neuron in the limb of a developing locust embryo is destroyed, the pathfinder neuron *a. grows in a more or less random direction, often never to find their proper destination. b. keep growing in the proper direction anyway, until they reach the next marker. c. cease growing until a new marker cell develops. d. allows another neuron to take over the pathfinding function. 101. The sensory neurons that in insects first start growing from the periphery toward the center in the developing embryo are called a. growth cones. *b. pioneer neurons. c. guidepost cells. d. none of the above. 102. Pioneer neurons are just like the sensory neurons that follow them in development. This statement is a. true, since the pioneer neurons become sensory cells themselves later in development. b. true, as shown by experiments in which normal pathfinding by sensory neurons followed destruction of all pioneer cells. c. false, because monoclonal antibody studies have shown that pioneer cells and sensory cells have completely different surface markers. *d. false, as shown by experiments in which normal pathfinding by sensory neurons was disrupted after destruction of all pioneer cells. 103. Filopodia are a. the enlarged tips of growing axons. b. the surface markers on cells, that allow developing neurons to find their way. *c. the filamentous thread-like structures that grow out from the tips of growing axons. d. none of the above. 104. The filamentous structures that project from growth cones of developing axons and help the cell find the right path to grow are called a. neural filaments. b. neural tubules. c. guideposts. *d. filopodia. 105. Axons developing in a grasshopper CNS *a. use other axons as markers to find their correct path. b. grow according to a genetic blueprint, without the necessity of external markers. c. make random synaptic connections that are rearranged according to the experience of the animal. d. require guidepost cells to locate the places where they should change direction. 106. In the locust CNS, filopodia seem to identify the cells they use as landmarks by a. sensing chemical markers released into the intercellular medium by their targets. b. being guided mechanically so they cannot miss their targets. *c. by wrapping around possible targets, and identifying the unique protein markers on the surfaces of their targets cells. d. by making synaptic contact with many cells, and recognizing their target cells because only those synapses made on the target cells survive. 107. Fasciclin II, a protein important in the recognition of one developing neuron by another, is expressed (produced) a. at all times during the developmental period. *b. only by specific neurons and at specific times during development. c. only when a neuron is contacted by specific filopodia. d. in all neurons, but only during a period of a few hours during development. 108. Corey Goodman a. demonstrated the presence of guidepost cells. b. showed that pioneer neurons were responsible for guiding the proper path of growth of sensory axons in insects. c. first proposed the chemoaffinity theory of neural development. *d. showed that axons in a developing insect nervous system could express specific proteins. 109. It has been shown in the developing locust CNS that certain immunoglobulin-like glycoproteins are expressed *a. only at one particular time during development and at one particular location on the neuron. b. only at one particular time, but all over the neuron. c. all the time during development, but only at one particular location. d. all the time during development and all over the neuron. 110. Use of the monoclonal antibody technique to study the developing nervous system has shown *a. the presence of distinct and unique proteins on the surface of neurons, that could act as identification markers for pathfinding during development. b. the tendency for neurons from one eye to make synaptic contacts in the visual cortex alternately with those of the other eye. c. that all pioneer neurons require properly placed guidepost cells in order to develop properly. d. that growth cones are topped with filopodia. 111. The technique that helps to make visible the location of specific, individual proteins in the nervous system is called the ____ß technique. a. Lucifer yellow *b. monoclonal antibody c. formaldehyde d. antigen-antibody