Behavioral Neuroscience Exam 2 ( Lecture 1: Development of the Nervous System)

Lecture 1: Development of the Nervous System

What are the three stages of Prenatal development?

1. germinal stage

2. embryonic stage

3. fetal stage

What is the timespan of the Germinal Stage and the name of the cluster of cells it creates?

zygote 

conception through the first two weeks of pregnancy 

What is a zygote?

The cell formed from the amalgamation of a sperm cell and an ovum.

What is the timespan of the Embryonic Stage and the name of the cluster of cells it creates?

2-8 weeks

embryo

What is the timespan of the Fetal Stage and the name of the cluster of cells it creates?

8 weeks to birth

What is a blastocyst?

The early formation of the “baby”

What is the trophoblast?

The placenta formation

What is implantation?

refers to transfer to the uterus

What is organogenesis?

formation of the organs

What is neural tube development?

development of the brain and spinal cord

What is the function of the endoderm?

to form the digestive and respiratory system

What is the function of the mesoderm?

to form the bones, muscle, and reproductive system

What is the function of the ectoderm?

to form the skin and nervous system

What is the function of the placenta?

to provide oxygen and nutrients to the growing baby 

a filter between mother and baby

What is the function of the umbilical cord?

it connects baby to the placenta 

What is the function of the amnion?

to protect the developing baby by forming the inner layer of the amniotic sac, which contains amniotic fluid

The amniotic fluid provides cushioning for the baby

What does the average weight and height of an American baby?

7 pounds and 6 ounces

20 inches long 

What are the stages of neurodevelopment?

Induction of the neutral plate

Neural Proliferation

Migration and Aggregation

Axon Growth and Synapse Formation

Neuron Death and Synapse rearrangement 

What is the Induction of the neural plate?

a small patch of ectodermal tissue on the dorsal surface of the developing embryo.

What is Neural proliferation?

The rapid increase in the number of neurons that follows the formation of the neural tube.

What is Migration and Aggregation?

Newly generated neurons migrate to their designated positions in the brain and begin to cluster together. 

What is Axon Growth and Synapse Formation?

Neurons extend axons to connect with other neurons or target tissues, forming synapses

What is Neuron Death and Synapse rearrangement?

A significant number of neurons undergo programmed cell death, and synapses are refined through a process of strengthening and weakening, leading to the final neural circuitry. 

What is a Totipotent?

a cell that has the ability to develop into any class of cell in the body (e.g., bone, skin, neuron, or heart cells).

What is a Multipotent?

Capable of developing into different cells of only one class of cells (e.g., different kinds of blood cells).

What is a Stem cell?

Cells that have an almost unlimited capacity for self-renewal and the ability to develop into many different types of cells.

What is the Ventricular zone?

The region adjacent to the ventricle in the developing neural tube. 

What is radial migration?

Movement of cells in the developing neural tube from the ventricular zone in a straight line outward toward the tube’s outer wall.

“perpendicular”

What is somal translocation?

the developing cell has a process that extends from its cell body that seems to explore the immediate environment.

What is tangential migration?

Movement of cells in the developing neural tube in a direction parallel to the tube’s walls.

“parallel”

What are the three layers of embryonic cells?

endoderm

mesoderm

ectoderm

What is glia-mediated migration?

the developing cell uses the long process that extends from each radial-glia cell as a sort of rope along which it pulls itself up and away from the ventricular zone

Aggregation

developing neurons align themselves with other developing neurons that have migrated to the same area to form the structures of the nervous system

What is a growth cone?

Amoebalike structure at the tip of each growing axon or dendrite that guides growth to the appropriate target.

What is the Chemoaffinity hypothesis?

The hypothesis that growing axons are attracted to the correct targets by different chemicals released by the target sites.

What is synaptogenesis?

the formation of new synapses

What is necrosis?

Passive cell death 

What is apoptosis?

Active cell death

What is a pioneer grow cone?

The first growth cones to travel along a particular route in the developing nervous system

What is safer necrosis or apoptosis?

Apoptosis is safer

Necrotic cells break apart and spill their contents into the surrounding extracellular fluid,

and the consequence is potentially harmful inflammation

BUT

In Apoptosis, cell remains are recycled and cleaned up

What is neurogenesis?

the growth of new neurons

What is fasciculation?

The tendency of developing axons to grow along the paths established by preceding axons is called fasciculation

What are the functions of neurotrophins?

promote the growth and survival of neurons, function as axon guidance molecules, and stimulate synaptogenesis

What is synapse rearrangement?

The synaptic contacts of each axon become focused on a smaller number of cells.

A more focused pattern of synaptic contact is present after synapse rearrangement. 

True or False: Pruning occurs throughout development

True

At _______, each neuron has about _______ connections.

birth, 2,500

______weight triples over the course of the first _____ years of life.

Brain, 2

What is myelinization?

formation of myelin sheath

What is working memory?

keeping relevant information accessible for short periods of time while a task is being completed

What is pruning?

eliminating unused or weak synaptic connections

What is role of the prefrontal cortex?

working memory

planning and carrying out sequence of action

inhibiting responses that are inappropriate in the current context (related to social skills or code switching) 

True or False: One of the principles that has emerged from the study of neurodevelopment is that neurons seem to be in an uncompetitive situation.

False

They compete with other neurons for synaptic sites and neurotrophins, and the losers die. (Survival of the fiitest)  

Effects of Deprivation vs Enrichment

Rats raised from birth in the dark were found to have fewer synapses and fewer dendritic spines in their primary visual cortex, and as adults, they were found to have deficits in depth and pattern vision. In contrast, rats raised in enriched environments were found to have a thicker cortex, with more dendritic spines and more synapses per neuron.

Give an example of the Competitive nature of the brain

ocular dominance columns in the primary visual cortex

Ex: When only one eye is blindfolded, the ability of that eye to activate the visual

cortex is reduced, whereas the ability of the other eye is increased. Both of these effects occur because early monocular deprivation changes the pattern of synaptic input into the primary visual cortex

True/False: Neuroplasticity is always good.

False 

Bad: trauma and addiction can lead to poor mental health