BioPsych: Chapter 4

When does the CNS begin to form in the embryo?

About 2 weeks

By what week of development are the hindbrain, midbrain, and forebrain differentiated?

By 7 weeks.

What is the average brain weight at birth?

About 350 grams

Around what age is the prefrontal cortex developed enough for object permanence?

About 9 months after birth

What is object permanence?

The understanding that objects continue to exist even when they cannot be directly observed or sensed

What structure does the neural tube form from, and what does it become?

It curls from the embryo’s early structure and becomes the start of the CNS and central canal.

What do the four pockets at the top of the neural tube develop into?

The ventricles (fluid-filled spaces in the brain)

How much does the brain weigh by the end of the first year?

About 1000 grams (close to adult weight of 1200–1400 grams)

What are the 5 processes in neuron development?

Proliferation, migration, differentiation, myelination, synaptogenesis

What happens during proliferation?

Production of new cells in the ventricles; some stay as stem cells, some become primitive neurons or glia

What is the difference between symmetrical and asymmetrical division?

Symmetrical → 2 identical cells. Asymmetrical → 1 stem cell + 1 specialized cell

What happens during migration?

Cells follow chemical paths to their final destination

What happens if proliferation or migration is disrupted?

Intellectual disability

What happens during differentiation?

Primitive neurons form axons and dendrites. Axons usually grow first, dendrites after final location is reached

What is myelination, and what cells produce myelin?

The insulating sheath that speeds transmission, produced by glia (Schwann Cell and Oligenodendricites)

What is synaptogenesis, and what nutrient is essential for it?

Formation of synapses (continues through life); cholesterol is essential

Why are more neurons produced than needed?

To ensure there are enough; survival depends on proper connections

What is apoptosis?

Programmed cell death when a neuron fails to make appropriate connections

What two conditions must neurons meet to survive?

Form synapse with target cell + receive NGF (nerve growth factor)

What are neurotrophins?

Growth-promoting proteins (like NGF) that support neuron survival and recovery

What two activities increase neurotrophin release?

Exercise and learning new things

What is Neural Darwinism?

The process where only the strongest and most connected neurons survive

How do axons know where to connect?

They follow chemical gradients

What did Sperry’s rotated newt eye experiment show?

Axons regrew to their original targets, guided by chemical gradients

Why is the brain considered “plastic”?

Because experience can change brain structure and connections.

What increases dendritic branching and cortical thickness?

Enriched environment, exercise, and education

What effect does exercise have on the brain?

Increases neurotrophin release and dendritic branching

Where can new neurons form in adulthood?

Olfactory receptors and possibly hippocampus

What animals show adult neurogenesis for memory or song?

Birds (songbirds, chickadees)

How is a musician’s brain different?

Enlarged temporal cortex (auditory area) and reorganization of motor areas for fingers

Why is the developing brain more vulnerable than the adult brain?

More sensitive to malnutrition, toxins, infections, anesthesia, etc.

What are common effects of fetal alcohol syndrome?

Heart defects, facial abnormalities, short dendrites with few branches, severe mental health issues

What is the Kennard Principle?

Recovery is generally better after brain damage in younger brains

What are the two types of stroke?

Ischemia (blood clot blocks artery) and hemorrhage (artery rupture)

What drug breaks up blood clots in ischemic stroke?

Tissue plasminogen activator (tPA)

What treatment has been most effective for brain survival after stroke?

Cooling the brain (91–97°F for ~3 days)