Question 1
[For questions 15] A uniform cable with diam=4 μm has R
m
= 10KΩcm2 and R
i
= 100 Ωcm with
λ = sqrt ((diam/4)(R
m
/ R
i
)), and R
in
= sqrt(R
m
R
i
)/ (π d
3/2
). The cable has a branch point at location
X that gives rise to 3 unequal daughter branches of diameter d, 2d, and 3d respectively, so that
the input conductances are matched facing either direction from the branch point. You inject a
current in the main cable 0.8 λ (where λ is the length constant of the parent cable) away from the
branch point at location Y, leading to a 20 mV depolarization at the branch point. What is the
value of d in microns?
Answer
0.922802
Question 2
Calculate the input resistance at location Y in MOhms.
Answer
39.7887
Question 3
Calculate the space constant in microns.
Answer
1000
Question 4
What does V need to be at the injection site? (in mV)
Answer
44.5108
Question 5
How much current do you need to inject at the injection site? (in nA)
Answer
1.11868
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Consider the 2 experiments shown in the illustration. The experiments are carried out
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 Spring '06
 Mel
 Ri, Branch point

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