S2 W3 Prenatal development

Question 1

Natal

Answer 1

of one’s birth, processes of birth/pregnancy

Question 2

Prenatal development

Answer 2

development of huans before they are born

Question 3

Postnatal development

Answer 3

development of human after they are born, often specifically referring to infancy

Question 4

Neonate

Answer 4

an infant who is less than a month old

Question 5

Prenatal Periods

Answer 5

1-Germinal period (single cell zygote => morula =>blastocyst) = conception to attachment to uterine wall. 0 to 10 days

2-Embryonic period (embryo) = attachment to uterine wall ends in the 8W when all major organs have taken primitive shape. 2 to 8 GW

3-Fetal period (fetus) = largest amount spent in this period.9GW to Birth

Question 6

3 gerlan layers

Answer 6

Endoderm = the inner lining of some systems and some organs such as the liver and pancreas.
Mesoderm = bones, muscles, the heart and circulatory system, and internal sex organs.
Ectoderm = skin, the brain, and the nervous system

Question 7

What is an ectoderm?

Answer 7

It becomes a neural plate, which differentiates into cells, that will become the fore/mid/hindbrain. Neural plate folds to become neural tube.

Question 8

Prenatal indirect methods

Answer 8

Presenting loud sounds on surface of abdomen and asking mothers to report fetus movement.
Inferences from non-human animal models.
Autopsy of human embryos and fetuses.
Inferences from studies measuring the perception and memory of neonates.
=> Practical, ethical issues

Question 9

Prenatal direct study methods

Answer 9

Fetal ultrasound, brain acitivty using fMRI

Question 10

Phases of Brain development

Answer 10

Neurulation / Neural plate induction
Neurogenesis / Neural proliferation
Migration / Neuronal migration
Maturation / Dendrite and axon growth
Synaptogenesis / Synapse formation
Apoptosis / Neuronal death
Myogenesis / Formation of myelin

Question 11

Neurulation neural plate induction

Answer 11

The ectoderm becomes the neural plate - a patch of tissue on the dorsal surface of the embryo that will become the nervous system.
Development induced by chemical signals.
Growth factors - several chemicals produced in developing and mature brains that stimulate neuron development and help neurons respond to injury.

Question 12

Impact: neural tube defects (NTD)

Answer 12

Genetic/environmental factors: increase risk of NTDs. Maternal folic acid supplements have been demonstrated as effective in reducing the risk of NTDs

Question 13

Neurogenesis

Answer 13

Two types of cells: neurons, glial cells ( = outnumber neurons, nourish, repair and myelinate neurons, crucial for development.)

Question 14

Neural proliferation

Answer 14

neurogenesis continues after birth. Proliferation is a part of neurogenesis - i.e., the generation of new cells via mitosis. The multipotent cells turn into neuroblasts and glioblast which then become the neurons and glial cells during migration

Question 15

Migration/neuraonal migration

Answer 15

Radial glial cells: act as guide wires for the migration of neurons. Migrating cells are immature, lacking dendrites. Cells that are done migrating align themselves with other cells and form structures (i.e., they aggregate).

Question 16

neuronal migration disorder (NMD)

Answer 16

characterized by neurological deficits in childhood. Most common symptom of NMD is intractable epilepsy.
Causes (can vary): genetic in origin and multiple genetic disruptions/mutations have been associated with NMD.

Question 17

Maturation/Dendrite and axon growth

Answer 17

Once migration is complete and structures have formed, axons and dendrites begin to grow to their ‘mature’ size/shape.
Axons (with growth cones on end) and dendrites form a synapse with other neurons or tissue (e.g., muscle).
Growth cones and chemo-attractants are critical for this stage

Question 18

Synaptogenesis / Synapse formation

Answer 18

multi-stage process. Dependent on the presence of glial cells – especially astrocytes.
Therefore, occurs at about 23 weeks of gestation after migration. Many synapses form randomly (as axons and dendrites meet).
Chemical signal exchange between pre- and postsynaptic neurons is needed.

Question 19

Neuronal death, apoptosis

Answer 19

Between 40-75% neurons made, will die after migration – death is normal and necessary (within reason). Neurons die due to failure to compete for chemicals provided by targets.
Neurotrophins: promote growth and survival, guide axons, stimulate synaptogenesis.

Question 20

Myogenesis / Formation of myelin

Answer 20

Myelination begins in PNS at 2MG. Motor roots become myelinated before sensory roots. 3rd trimester myelinatin occurs in CNS (first in sensory tracts).

Question 21

Synaptic prunning

Answer 21

Pruning improves the efficiency of the brain and the transmission of signals between neurons. Synaptic pruning is relatively slow prenatally and is most rapid following the 2nd year of life (Konkel, 2018).

Question 22

Fragile-X syndrome is a genetic disorder that:

Answer 22

results in developmental delays, learning disabilities, and behavioral problems;
is caused by a defective FMR1 gene which suppresses production of proteins that stimulate pruning.

Excess synapses are not pruned sufficiently. ‘Noise’ in the neural system causes symptoms such as attention deficit symptoms

Question 23

prenatal learning

Answer 23

At 6 months gestation, fetuses = have the capacity to learn despite immaturity of the foetal nervous system, show basic forms of memory (e.g., habitation of response to repeated auditory stimuli).