Elizabeth Collins

Question 1

In competitive growth between axons and their branches, which ever locale is experiencing a lower frequency of calcium influx will extend while the other locale experiencing a higher frequency of calcium influx will retract.

Answer 1

false

Question 2

Application of Netrin-1 to an axon will induce local calcium transients.

Answer 2

true

Question 3

Calcium influx has been shown (in different experiments) to do the following to growing axons:

Answer 3

cause axon retraction; cause promotion of axon growth

Question 4

BayK, a voltage gated Ca2+ channel activator, has been shown to experimentally do the following to growing axons and their branches:

Answer 4

cause an overall decrease in growth rates; and an increase in differential growth rates between axons and their branches.

Question 5

State what a Calcium transient is, and briefly describe what growth effects one might observe when experimentally varying the frequency of local calcium transients in an axon and that axon’s branches.

Answer 5

A Calcium transient is a calcium influx. This influx of calcium can either be global, all throughout the axon, or local, in specific limited areas of the axon. It has been shown that local calcium transients do occur in axons and their branches, meaning that axons can be experiencing a calcium influx at one rate while that axon’s branches can be experiencing a calcium influx at an entirely different rate. When the axon and it’s branch are experiencing different frequencies of calcium influx, whichever has the higher frequency rate will grow. This growth is competitive, so as one part of the axon is growing, the other part that is experiencing a lower frequency will be retracting.