PSYC 210 Exam 2

What is an undifferentiated zygote?

a single cell that is a combination of your parents that divides many times to make up our body

Specification of genes meaning

Genes turn on and off, and are specified for different areas of the brain

Do genes turn back on after they've been turned off?

Some do, but others turn on during development and never turn back on again

Blastula

An unspecified ball of cells

What do identical twins come from?

From breaking off of the blastula

When does the ectoderm form?

14-18 days after fertilization

ectoderm, mesoderm, endoderm

Neural tube -- 18 days

Neural plate forms (skin or nervous system)

Neural tube -- 21 days

Neural groove forms

Neural tube -- 22 days

Neural groove is closing to form the neural tube --> neural tube ventricle

Neural tube -- 23 days

Anterior neural folds close to form brain --> neural tube is fully formed

Neural tube -- 24 days

Brain and spinal cord are fully developed and contain the neural tube, developing forebrain, and developing heart

The neural tube is part of what nervous system?

The CNS

The neural crest is part of what nervous system?

The PNS

Neural Crest

A band of cells along the border where the neural tube pinches off from the ectoderm (found above the tube)

What happens to the human embryo at 7 weeks?

The brain forms via cell division and contracting cells form the heart

T/F: All vertebrates have a brain and spinal cord

True

How do vertebrates differ between early and late development?

In early development, all vertebrates look the same but in later development, all vertebrates look different

Stages of neural development

1. Proliferation

2. Migration

3. Differentiation

4. Pruning and Cell Death

5. Myelination

Proliferation

Cell division

Where does proliferation occur?

In the neural tube

Migration

Neuroblasts; when cells are done dividing, they move out of the tube and to the outside of the central canal, creating a bump and eventually becoming neurons

Differentiation

Forming axons and dendrites, and making synapses --> ultimately forms the neuron

Axon Terminals

Branches at the end of the axon that make many synapses

Neurotrophic Factors

Proteins responsible for growth and survival of neurons during development and maintaining adult neurons

Growth Cone

Growing tip of axon or dendrite that forms appropriate synaptic connections

Target cells secrete ___

Neurotrophic factors

Explain what the growing axon does

Axon makes a synapse and gives off neurotransmitters that target cells interact with to get neurotrophic factors

There is a series of attraction between the growing tip of the axon and what?

The rest of the growing nervous system

CAM Cell Adhesion Molecules

Proteins that allow cells to recognize each other and contribute to proper cell differentiation and development

• Forms proper chemical attractions or repulsions from what it needs

Examples of neurotrophic factors

1. NGF --> nerve growth factor

2. BDNF --> brain derived neurotrophic factor

Pruning and Cell Death

Apoptosis, where you injure the cell by draining its blood supply or set off its genetic program for killing it

What stage does pruning and cell death overlap with?

Differentiation

What is apoptosis? When does it occur?

A genetic program for cell death due to too little neurotrophic factor; occurs around birth in the cortex

___x as many neurons are generated in the spinal cord than will stay

2x

Pruning

Even when new synapses are being made, unnecessary and unused connections are being removed

Do neurons get replaced/regenerated?

No; once they divide, they'll never divide again

Myelination

Wrapping of glial cells around the axon to speed up chemical transmission

When does myelination occur?

Mainly after pruning and cell death is finished

Why does myelin stop/end?

In order for synapses to be made

Schwann Cells

Form myelin in the PNS

Oligodendroglia

Form myelin in the CNS

What 2 stages of neural development are babies already born with?

Proliferation and migration

Which stage of neural development starts prenatally, but differentiates after birth?

Differentiation

What is the first kind of synapse to occur in development?

Spinal synapses

Maturation of spinal cord

Spinal cord --> subcortex ----> cortex

Brain weight increases from birth to 12 years old by ____x

3.5x

At what size is the brain pretty much at adult size

12 years old; connections are not yet fully formed though

Proliferation: cerebellum (how long does it continue for?)

Continues for 2 years

Proliferation: olfactory bulb

Continues for life; highest proliferation during 1st year

Proliferation: dentate gyrus of hippocampus

Continues for life; highest proliferation during 1st year

When does most differentiation occur?

Before birth

Less than ___% of brain cell proliferation occurs from the cerebellum, olfactory bulb, and dentate gyrus of hippocampus

0.5%

T/F: Exposure to many substances (toxins) during development can have permanent effects on the brain

True

When are these permanent effects greater?

During early childhood, as opposed to later in childhood or adulthood

Toxins vs Toxicants

Toxins = occuring in nature

• Reptiles, insects, plants and microorganisms

Toxicants = human made

• alcohol, lead, pesticides, BPA, phthalates, most drugs

T/F: Most toxins get through the placental barrier

True

How do areas of the cerebral cortex develop?

They develop at different times

Development: Sensory

Highest after birth; babies don't see find detail nor have great acuity --> we're born with neurons but not connections

Development: Motor/Language

Middle stage of development

Development: Higher Cognition

Last stage of development; continues throughout childhood and into adolescence

Dendritic Growth

Mature neurons generally can't divide, but new dendrites can grow --> newborns to 2 years gradually increase in dendritic connections

___ are pre-wired from birth

Axons

Binocular Vision

Vision using two eyes with overlapping fields of view, allowing good depth perception

What happens if your right eye is blurry?

Your left eye takes over more of the cortex because the right eye doesn't see fine detail

What happens when axons compete for synaptic space?

Growth of axons and pruning both occur

You will always have a weaker eye if not corrected by ___ months of age

18 months

Amblyopia

Eyes out of alignment --> the dominant eye takes over; AKA lazy eye

Glutamate

The most common excitatory neurotransmitter in the CNS

2 types of glutamate receptors

AMPA and NDMA

AMPA

Ionotropic glutamate receptor that ALWAYS opens and leads to an EPSP

NDMA

Ionotropic glutamate receptor that only opens via membrane depolarization to create an EPSP

Synaptic Strengthening

Synapses that work together to strengthen each other

Binocular Neurons

Wiring of visual cortex --> using both eyes

Left eye: Axon releases glutamate repeatedly -->

AMPA receptor --> much Na+ enters

NMDA receptor --> Na+ and Ca++ enter from depolarization

Right eye: Axon releases glutamate repeatedly -->

AMPA receptor --> Much Na+ enters

Does the right eye or the left eye have not many AMPA receptors?

The left eye

Steps in NMDA coincidence detection

1. Several AMPA receptors in close proximity used simultaneously results in increased depolarization

2. NMDA opens and lets Ca++ into the dendrite

3. Ca++ starts a chemical cascade that results in more AMPA receptors being put into the membrane

4. This results in a stronger synapse

Enriched Condition (EC)

Also called complex environment. A condition in which laboratory rodents are group-housed with a wide variety of stimulus objects.

Does proliferation occur after birth?

No

What is the cerebral cortex during the first year after birth?

The visual cortex

What is the cerebral cortex through adolescence?

The prefrontal cortex

Prefrontal Cortex

Involved with executive functions, decision-making, etc.

When does the prefrontal cortex develop?

Mid 20s

What kind of milk do babies need for growth? Why?

Fatty milk to help myelinate axons and increase connections

Who develops frontal grey matter earlier, males or females?

Females

When does frontal grey matter peak?

During adolescence