Week 5: Neurodevelopment and Neuroplasticity

Question 1

Development

Answer 1

A change in a property of neurobiology over time (ex: myelination, brain growth, etc)

Question 2

Prenatal development stages

Answer 2

1: Induction of the neural plate
2: Neuronal Proliferation
3: Migration
4: Axonal growth
5: Cell death

Question 3

Stage 1

Answer 3

Layers develop 18 days after conception (ecto-, meso-, and endoderm). Stem cells accumulate en mass in the neural plate on the ectoderm. Neuronal tube and basic brain structures form after 24 days

Question 4

Stem cells

Answer 4

Can generate sub-types of cells. Are highly able to differentiate, but after they differentiate they can only produce that type of cell

Question 5

Stage 2

Answer 5

Rapid neuron creation; more than we need. Made in the ventricular zone before migrating to final destination

Question 6

Stage 3

Answer 6

Cells move either radially (out from the center) or tangentially (any other pathway). Deep layers form first, then cells move outwards. Follows aggregation

Question 7

Aggregation

Answer 7

Migrating cells organize themselves in a particular way; mishaps in alignment could correspond to disorders

Question 8

Stage 4

Answer 8

When cells reach their final point, their axons grow toward biologically predetermined destinations. The growth cone at the end of the axon is guided by attractive and repulsive chemicals.

Question 9

Fascigulation

Answer 9

Pioneer axons will blaze a trail that other axons will follow when growing. Leads to the formation of tracts.

Question 10

Sperry frog experiment

Answer 10

Examining if spatial proximity determined axon growth. Cut axons in a frogs eye, then rotated it to see if the axons would reconnect differently. Found that they will still grow toward their original target, even when rotated

Question 11

Chemoaffinity theory of axon growth

Answer 11

Growth patterns are guided by one growth factor per growth pattern.
DISPROVEN: lesion studies found that axons are sensitive to more than one chemical

Question 12

Topographic gradient hypothesis

Answer 12

Concentration of chemicals guides axon growth. Arguing topographic gradient of chemicals

Question 13

Synaptogenesis

Answer 13

Formation of synapses. Facilitated by glial cells. Weaker connection will be pruned or die. Occurs very rarely past a certain developmental point

Question 14

Neurotrophin hypothesis of synaptogenesis

Answer 14

There is a competition for neurotrophin signals; the more you get the more likely you survive

Question 15

Stage 5

Answer 15

Cell death. Apoptosis is programmed and clean; neurosis is spontaneous and messy
Strongest cells are selected for due to limited brain resources

Question 16

Synapse elimination

Answer 16

Facilitated by glial cells. With repeated activation, synapses can get weaker or stronger over time

Question 17

Causes of change in synaptic density

Answer 17

The brain grows x4 in size over life (synaptogenesis, dendritic growth, myelination); brain areas mature at different rates

Question 18

Critical period

Answer 18

A period of development where stimulus is required for development. End due to limitations on growth and/or myelination

Question 19

Sensitive period

Answer 19

A period where stimulus is more powerful in affecting development. Has environmental and psychological factors that motivate or inhibit learning

Question 20

Adult neurogenesis

Answer 20

Very rare; only occurs in the hippocampus and the olfactory bulb. New cells take 4-6 weeks to develop and are more plastic and more excitable

Question 21

Benefits of Hippocampal neurogenesis

Answer 21

Has been found to improve memory and reduce anxiety. Consistent with the link btw the hippocampus and mood

Question 22

Traits of Neurodevelopmental disorders

Answer 22

High heritability; emerge early in life; high comorbidity rate

Question 23

Schizophrenia

Answer 23

Symptoms: positive and negative (adding sensation or loss of sensation)
Causes: dopamine transmission defects; excessive pruning of cortical areas; abnormal cell organization
Physiological: reduced grey matter in hippocampus and orbitofrontal cortex
Heterogenous disorder

Question 24

DA Hypothesis of Schizophrenia

Answer 24

Too much dopamine in specific pathways (high in mesolimbic, low in mesocortical) correlates with positive symptoms

Question 25

Autism Spectrum Disorder (ASD)

Answer 25

Symptoms: poor social interaction, repetitive behaviors, slow language development
Causes: Unknown. Diagnoses are increasing due to awareness and advancements in technology
Physiological: high number of synapses/too much gray matter
Heterogenous disorder

Question 26

Attention Deficit Hyperactivity Disorder (ADHD)

Answer 26

Symptoms: inattentive and hyperactivity (can be solo or combined)
Causes: maturational delay in the prefrontal cortex; affects 6-10% of the population; lower dopamine levels
Physiological: reduced cortical volume in the prefrontal cortex
Treatment: icrease dopamine and noradrenergic transmission

Question 27

Psychopathy and Anti-social Personality Disorders (ASPD)

Answer 27

Traits: guiltless, manipulative, aware of actions and not changing or caring; typically charismatic and popular
Genetic and environmental risks; difficult to study due to ethics
Physiological: reduced function in frontal cortex and amygdala

Question 28

Low arousal theory of ASPD

Answer 28

Reduced response to threats which decreases impulse control and causes a continual need for stimulation