study_questions_for_the_final_exam_key - Page 1

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1a. Would a 2 point discrimination task be easier on your lips or on your back? Lips 1b. Explain your answer to 1a. The magnification factor in the cortex is very large for the lips, so there are very many cortical cells responding to touching the lips, so the lips are more sensitive. Also, there are many more receptors in the periphery on the lips, and therefore these receptors have smaller receptive fields, so they can resolve stimuli that are very close together (for full credit you would have to mention both reasons) 2a. You record from a cell where repeated firing of a synapse causes an increase in the size of the excitatory post-synaptic potential. What is this process called? Sensitization or facilitation or potentiation (any one of these would be considered correct) 2b. Describe in as much detail as you can the cellular mechanism underlying this process. Residual calcium theory. Calcium entering the cell during previous action
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Unformatted text preview: potentials is mostly removed from the cytoplasm, but a small amount remains. Because the probability of neurotransmitter release is proportional to [Ca++] 4 , this effect is very non-linear, so a small amount of residual calcium can have a big effect on the amount of transmitter released (by greatly increasing the number of vesicles binding), and therefore on the increased size of the EPSP. 3a. How would you calculate the membrane potential of a cell? Use the GHK Equation RT/F(p K +[ K + ] o + p Na + [Na+] o + p Cl-[Cl-] i ) /( p K +[ K + ] i + p Na + [Na+] i + p Cl-[Cl-] o) 3b. A cells membrane potential is 70 mV, and the concentration of chloride is equal inside and outside of the cell. If you apply neurotransmitter which opens a ligand-gated chloride channel, will the post-synaptic potential be hyperpolarizing or depolarizing? Depolarizing. 3c. Explain your answer to 3b. Demo...
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This note was uploaded on 05/24/2010 for the course BIS BIS102 taught by Professor Hilt during the Winter '08 term at UC Davis.

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