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Unformatted text preview: Neuroscience 1-100 1. The proper sensory nucleus is derived from which of the following A. Alar plate B. Basal plate C. Sulcus limitans D. Neural crest E. Roof plate F. Mesencephalon G. Floor plate H. Rathke's pouch I. Rhombic lips The answer is: A Structures associated with sensory functions, such as the proper sensory nucleus and the spinal nucleus of cranial nerve V, are derived from the alar plate 2. A brain MRI scan taken from a 6-month-old baby revealed that while the overall size of the cerebral cortex was normal, the size of the pyramidal tracts was considerably smaller than normal. Which of the following is the most likely explanation for this defect A. Reduction in the numbers of cortical neurons giving rise to pyramidal tract fibers B. Reduction in the numbers of synaptic contacts made by pyramidal tract neurons C. Reduction in the extent of myelin found on pyramidal tract neurons D. Reduction in the amount of neurotransmitter released by pyramidal tract neurons E. Reduction in the numbers of glial cells attached to pyramidal tract neurons The answer is: C Extensive myelination occurs in postnatal development. The failure of the pyramidal tracts to form myelin would account for the reduction in their size. In this particular situation, the size of the cerebral cortex was approximately normal, suggesting that there was no significant decrease in cortical cells. Variation in the numbers of synaptic contacts, transmitter formation, and glial cells would not account for a reduction in the size of the pyramidal tract 3. Which of the following is the most ubiquitous excitatory neurotransmitter in the brain? A. ACh B. Glutamate C. Norepinephrine D. Dopamine E. Substance P The answer is: B The largest numbers of excitatory synapses in the CNS are mediated by glutamate as it is believed that approximately half of the synapses in the brain release glutamate. For example, functions mediated by fibers that originate from the cerebral cortex and descend to such regions as the neostriatum, thalamus, brainstem, and spinal cord are generally believed to be mediated by glutamate. Many other neuronal systems throughout the brain and spinal cord utilize glutamate as well. Dopaminergic and noradrenergic neurons, while mostly excitatory, can also be inhibitory at some synapses and are less numerous than glutamate. Cholinergic and substance P synapses are also excitatory, but are likewise less numerous than glutamate. 4. Epileptiform activity is believed to include the activation of which of the following A. GABA receptors B. Glutamate receptors C. Nicotinic receptors D. Serotonin receptors E. Glycine receptors The answer is: B Excitatory amino acids and, in particular, the glutamate family of compounds have long been thought to play an important role in epileptiform activity. Epileptiform activity typically includes AMPA-receptor activation. However, as the seizure becomes more intense, there is increased involvement of NMDA receptors. This is evidenced by the intense, there is increased involvement of NMDA receptors....
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