Development and Plasticity

Question 1

What is the neural tube?

Answer 1

Early on, the embryo forms 3 layers of cells: mesoderm, endoderm, and ectoderm.

The ectoderm becomes the skin and nervous system.

      Part of the ectoderm folds into form a 
      groove, which then becomes the neural 
      tube.

• The entire CNS develops from cells that form the walls of the neural tube. The inside of the neural tube becomes the ventricles and central canal of the spinal cord.

Question 2

What is cell proliferation?

Answer 2

• Stem cells are pluripotent: can become anything. They divide to produce “daughters” with the same DNA but may receive signals that activate certain genes that make them progenitor cells, destined to become a certain type of tissue.
• Neural progenitor cells are born in the ventricular zone (inner layer) of the wall of the neural tube.
• These cells can divide to produce more progenitor cells, or they become actual neurons/glia. This is neurogenesis.

Question 3

What is cell migration in the cortex?

Answer 3

Neural progenitor cells (aka precursor cells) are born in the ventricular zone, then crawl up radial glial cells to the outermost layer of the developing cortex.

These baby cells crawl towards chemoattractants released at the upper level (and perhaps away from chemorepellants)

Question 4

What is neuron differentiation?

Answer 4

Neuron differentiation refers to the process by which immature or undifferentiated neural cells, known as neural progenitor cells, undergo a series of molecular and morphological changes to become fully mature neurons.

blood cells, muscle cells, etc

Question 5

What is axon guidance?

Answer 5

The tip of the growing axon is called the grown cone.

It allows growing axons to reach specific destinations and ultimately form the complex neuronal networks throughout the body.

Axons crawl along an extracellular matrix of cell adhesion molecules, guided by chemical cues that are diffused through the developing brain: chemoattractants and chemorepellants.

Question 6

What is apoptosis?

Answer 6

programmed cell death

“use it or lose it”

Question 7

What is a critical period?

Answer 7

A critical period is a window of time, typically in early development, during which a system can be changed by input from the environment.

• Before and after this period, environmental influences cannot affect the sensitivity or response of that system.