cognitive development

&

emotional development

2-3 weeks after fertilization the blastocyst becomes a ______.

At this point, gametes (___ & ___) are set aside.

gastrula

eggs & sperm

parts of the body that arise from teh ectoderm

_____

____

____

facial ____ & ____

____ cells

skin

hair

CNS

facial bones & tissues

sensory neurons

pigment cells

body parts that arise from the mesoderm:

____ system

____

___ / ____

____

______ tissue

circulatory system

kidneys

testes/ovaries

muscle

bone

connective tissue (ligaments, cartilage)

body parts that arise from the endoderm:

digestive organs

-_____

-_____

-_____

-_____

_________

_________

digestive organs:

-stomach

-liver

-pancreas

-intestines

lungs

thyroid

Nervous system development

neural groove begins to develop - ___ days

 closes lengthwise forming a tube - ___ days

a few days later, the 4 major brain divisions are observable:

1-

2-

3-

4-

20 days

22 days

telencephalon

diencephalon

mesencephalon

rhombencephalon

Step 1. Proliferation

-occurs in ____ zone

-rate can be ____k/min

-___ phase (mitosis) = 2 duplicate cells

- phase = one neuron created

ventricular zone

250k/min

symmetrical

asymmetrical

Step 2. Migration

 Neurons leave ____ zone with ____ glia acting as guide wires.

Neuron attached to glia by cell ____ molecules.

ventricular zone w/ radial glia guide wires

... by cell surface molecules

columns

cerebral cortex

2. Migration is inside-out:

word bank:  'first'   'last'

neurons arrive:

____ in deepest cortical layers (5 and 6)

____ in most superficial layers (1 and 2)

first in deepest

last in most superficial

3. Differentiation

3 steps of differentiation:

a) develop ____ (____ and ___)

b) make _____

c) develop ____  _____

processes (axons and dendrites)

make NTs

develop electrical conduction

(3. differrentiation)

when is a neuron's type determined?

3. differentiation

if embryonic cells from ventricular zone transplanted to a newborn host animal's brain they

a) migrate to:

b) take on the morphology that is:

migrate to the cortical layer expected for their age

age-appropriate

4. Aggregation

What do neurons of the same type (e.g. pyramidal cells) do during this stage of nervous system development?

5. Synaptogenesis

What happens in this phase?

5. synaptogenesis

when does it begin?  ____ weeks

 when does it peak? ___________

How many synapses per neuron in the cereberal cortex of a newborn?

begins - 23 weeks

peaks - in the 1st year

2500 synapses per neuron (in cereb. cortex)

6. Neuron Death

 What % of neurons born in embryonic/fetal development don't survive?

7. Synaptic Pruning

 What is it?

7. synaptic pruning

 What leads to the overabundance of synapses?

How many synapses per cereb cortex neuron by age 2 or 3?

How many for an avg adult?

What is one condition associated with too much pruning?

-synaptogenesis

 ~ 15000

~7500

-too much associated w/ schizo

7. syn. pruning

The progression of pruning can vary by _____ region

8. myelination

What is myelin made of?

Myelin  :: increases / decreases :: conduction velocity

After birth, myelination:

a) stops completely

b) slows down

c) continues at the same pace but only until puberty

d) continues into adulthood

it's lipid/protein

increases v

d) continues to adulthood

Full myelination is achieved around age ___.

Some people believe this is related to the ___ behaviors associated with that age and the years preceding it.

20

risky

learning

injury

Visual cortex plasticity

in early V1 regions, L/R eye inputs segregated into _____ dominance columns.

 if sew one of cat's eyes shut during critical period, can't see out of that eye ever for neural reasons

what happens if try it to adult cat? _____

ocular dominance columns

results for adult are halfway between the kitten and an adult that's never been deprived

the main point of the blindfold/braille plasticity study was that if deprived of sight, neurons from the ______ system can handle ________ processing. (because of plasticity)

brain imaging revealed that:  upon tactile stimulation, greater activity in the ____ cortex was observed for those that had been blindfolded

effect lasted only ___ hours

visual

tactile

visual

20

Plasticity examples for somatosensory cortex:

1) (already knew) - monkey finger amputated, its associated neurons became associated w/ ____ fingers

2) man w/ arm amputation felt as if his ___  was being touched every time his face was touched

 3) violin players have _____ somatosens. rep.s of certain digits

neighboring

 hand / (arm)

 larger / greater

15-30 minutes

Less-specific plasticity example with rats and their environments:

enriched env = ?

exercise = ?

both = ?

enriched env. = more synapses per neuron (esp. in hippocampus)

exercise = bigger capillaries in brain

both = better survival rate for new neurons in the hippocampus

Hydrocephalus is increased ______ size due to excessive _______.

Can compress brain leading to ______ and/or ______.

sometimes also causes massive cortical ______.

ventricle, csf

convulsions, retardation

reorganization

Hydrocephalus example:

French guy w/ below avg IQ but not retarded.

 had weak left leg.

It was determined he had hyd.ceph.

What was the reason concluded for his weakness and/or below avg iq?

short-term effects of plasticity

- ____ connections that already existed may be unveiled.

 Is it...

a) region that had weak cnxns is damaged. when new cnxns form they happen to form as strong cnxns.     OR

b) a certain neural pathway consists of weak cnxns but is never used cuz a diff. pathway is used. that diff. pathway is damaged so now the one w/ weak cnxns is used where weak cnxns were never used b4 for that process.

- may contribute to _______ in

motor cortex following _____.

weak

 reorginazation, amputation

in long-term plasticity leads to

growth of new _______ and/or _______.

**Not much else is known!