The myelination of central and peripheral axons occurs rapidly ...

[mcmcdaniel]

The myelination of central and peripheral axons occurs rapidly through the first few years of life. How can this developmental process explain the improved motor abilities of infants and toddlers?

Question 2

Rabies is caused by a virus that attacks the central nervous system. The virus is normally introduced by an animal bite that breaks the surface of the skin. Since the virus is not motile, how does it travel to the central nervous system?

[jaygar71]

Answer to Question 1

Without full myelination, information about limb movement and body position moves slowly to the CNS, and motor commands move slowly and erratically to the muscles. By the time the brain is aware of movement or position and can issue a motor command, the limb has already moved. When the motor command reaches the skeletal muscle, the response is no longer appropriate. As the neurons become fully myelinated, information processing speeds up, so we observe improved balance, coordination, and movement.

Answer to Question 2

When the skin is broken by an animal bite some cutaneous receptors are physically damaged. It is through these damaged axons that the virus gains entrance to the neuron. Retrograde axoplasmic transport carries the virus to the central nervous system, where it can reproduce and spread.

[mcmcdaniel]

Excellent

[tranoy]

TYSM