Behavioral Neuro Development & Hormones Quiz

neural plate

nursery of stem cells that becomes neurons

notochord

• embryonic/primitive midline

• becomes SC & vertebrae

spokes

• radial glial cells only present during development

• guide newly born neurons

• leading & trailing processes of neuron wrap around radial cells to move

• neural crest striations

telencephalon

becomes neocortex of frontal lobe

diencephalon

becomes thalamus & hypothalamus

mesencephalon

becomes midbrain

rhombencephalon

becomes hindbrain (medulla, pons)

neurogenesis

• mitotic division of non-neuronal cells (stem cells) to produce neurons

• neurons born near central canal

cell migration

movements of cells to establish distinct neuronal populations

differentiation

stem cells specialize into different types of neurons or glial cells in different areas of the brain

synaptogenesis

establishment of synaptic connections

apoptosis

cell death after not connecting

synapse rearrangement

loss of some and development of other synaptic connections

ventricular zone

• near central canal (eventually ventricular system)

• neurons & glial cells form up until birth (a little after)

dentate gyrus

• part of hippocampus

• 1 place in the brain with continuous neurogenesis through its lifespan

• memory formation, maintaining memories, resilient against effects of stress & trauma

cell adhesion molecules

• AKA CAMS

• released by spokes part to stick & climb to migrate

Migration Failiures

• reduced cell populations, disorderly arrangements, and behavioral disorders

• autism, down syndrome, fragile x syndrome, schizophrenia

cell autonomous

• gene itself in neuron gets expressed and become that neuron no matter where it is

• independent of neighboring cells

• predetermined migration

• ex. Cerebellar Purkinje Cells

induction

• differentiation (fate) dependent upon neighboring cells

• needs signal from outside the cell to tell it what to become

• ex. spinal motor neurons.- influenced by chemicals (ex. sonic hedgehog-protein)

growth cone

extends and has chemical sensors

lamellipodia

thin, flat, sheet-like membrane protrusions found at the leading edge of migrating cells

filopodia

projections of growth cone like “sniffers” looking for chemical signals

chemoattractants

“grow near me”

chemorepellents

“grow around me”

central canal becomes ___ ___, central canal = ____ ____

neural tube, lateral ventricles

embryonic layer that the NS originates in

ectoderm

18 days

• neural stem cells

• notochord

• neural plate

20 days

• central canal

• neural crest

22 days

• canal becomes neural tube

• central canal —> lateral ventricles

24 days

• telencephalon - becomes neocortex of frontal lobe

• diencephalon - thalamus & hypothalamus

• mesencephalon - midbrain

• rhombencephalon - hindbrain (medulla & pons)

41 weeks

• term pregnancy

• brain structure of a 1 week old newborn

• full structures & gyri and sulci

Postnatal Synapse Development

• 1st year - tremendous synaptic growth

• First 5 years - most important for developing connections in the brain

microdimene

calcium channels & receptors that compartmentalize the functions of calcium

calcium

• signal for apoptosis

1. cell destroys its own membrane

2. membrane collapses

3. microglia (etc) gobble up waste

4. proteases - 3 caspases ready to go but with a “parking break” on

IAP proteins

• inhibitor of apoptosis proteins

• “parking breaks” for proteases

diablo protein

• release IAPs and allows apoptosis to continue

• activated by calcium release from mitochondria

caspases

• proteases which are protein-dissolving

• 3 types

neurotrophic factor

• chemicals that promote cell survival and growth

• support life

• Types: nerve growth factor, brain-derived nerve growth factor, neurotrophin

nerve growth factor

• type of neurotrophic factor

• discovered by Rita Levi-Montalcini

• spinal ganglia and sympathetic nerve ganglia

• amount NGF released correlated with amount of innervation

brain-derived NTF

• type of nerve growth factor

• important in neural plasticity, learning, memory, normal function

• involved in anxiety & depression disorders

• important for life

neurotropins

• type of nerve growth factor

• family of NGF-like molecules

fluid mosaic model

describes the structure of the plasma membrane as a flexible lipid bilayer with protein, cholesterol, and carbohydrate molecules floating and moving laterally within it

2-way communication

presynaptic neuron takes in neurotropic factors from postsynaptic neuron, and vide versa

failing of neurotropic factors can trigger ___

apoptosis

intrinsic

• factors within a cell

• genes

extrinsic

• factors outside the cell

• nutrients, cell-to-cell interactions

genotype

sum of all genetic information

NATURE

phenotype

• sum of all physical characteristics

• interaction of genotype and extrinsic factor

NURTURE

epigenetics

• nature vs nurture to shape a whole person

• environmental factors (internal/external) interacting with genetics

• life experiences can switch on/off certain genes at certain times to affect phenotype

mutations

• sudden usually random change in genetic structure

• related to marked anatomical/physiological change

• could’ve been induced by chemicals or radiation

mutants

• animals with altered genes

• great subjects: links genes, proteins to anatomy, physiology, & behavior

trasnsgenic and knock-out mice

site-directed mutagenesis (mutation in 1 gene)

critical developmental periods

sensitive periods of time for development (like a window)

visual deprivation

blindness

amblyopia

• double-vision in one eye caused by misalignment of the eye in the orbit

• AKA lazy-eye

• can be surgically corrected if sone before 7-8 y/o

• realignment in adulthood does not restore normal vision because of reduced plasticity

binocular deprivation

causes loss of dendritic spines and reduction in synaptic density in visual cortex

monocular deprivation

• caused profound structural and functional changes in the thalamus and visual cortex (in cats)

• Hubel & Wiesel’s Experiments

altered ocular dominance

• response strength of a visual neuron to stimuli presented to either the L or R eye

• predominance of neurons that respond to input from one eye

• cells: usually equally excited by either eye

• need sustained light activity eyes

• loss of NTF - some cats had BDNF injected and this resulted in a healing effect

primary visual cortex

in the occipital lobe

ocular-dominance columns

• neurons respond preferentially to one eye

• arranged like columns

• all receive input from L & R eye

- left column dominant left eye input (& vice versa)

collateral sprouting

axon grows more axons and connects more

Phenylketonuria (PKU)

• recessive hereditary disorders of protein metabolism

• may cause mental retardation

• Preventative measures

  • diet low in phenylalamine, especially before age 2 (gene can be found, single-gene issue)

• Mechanism

  • aa (phenylalanine) —> protein —> clearance mechanisms can have too much or if they fail, accumulation of excess aa/protein —> clump & clog, push on neurons/glia —> kill cells

  • enzyme lacking to break down phenylalanine

Down Syndrome

• trisomy 21 (extra chromosome 21)

• related to age of mother (>45 = 1/40)

• IQ ~80, sometimes higher

• cortical abnormalities - brain looks older, resembling Alzheimer’s

• abnormal dendritic spine formation

• physical abnormalities

Fragile X Syndrome

• inherited mental retardation (mild - severe)

• long arm of X chromosome breaks off

• Features: elongated face, large ears, prominent chin

• more common in males (penetrance bc of 1 available X)

• Fragile sites = CGG (trinucleotide repeat)

Autism

• life-long developmental disorder with impaired social competence

• language and a narrow range of activities and interests

• spectrum disorder

• low functioning/nonverbal —> high functioning/IQ (Aspberger’s)

Brain differences in Autism

• smaller corpus callosum & cerebellar regions = delays in motor development & cognitive skills, gait

• developmental differences in hippocampus (smaller)

• developmental differences in amygdala (bigger)

ASD Rise in Diagnoses (possibly) Caused by…

• overdiagnosis in recent times

• underdiagnosis in previous times

• environmental changes

• vaccines (no)

• age of parent

Neural Changes During Aging

• myelin thickening

• slower processing/memory

• hippocampus shrinkage

• Alzheimer’s Disease - type of dementia

Alzheimer’s Disease

• type of dementia

• faliure of cognitive abilities: memory, orientation, identity loss

• probability increases with ages above 85

• no definitive diagnoses until autopsy

Causes & Mechanism of Alzheimer’s Diseas

• loss of dopaminergic and cholinergic neurons, receptors, or connections throughout the cortex

• 3 major characteristics

  • senile plaques

  • neurofibrillary tangles

  • basal forebrain nuclei disappear

senile plaques

build-up of a protein called beta-amyloid

beta-amyloid

protein at which normal levels healthy for a brain

neurofibrillary tangles

abnormal twisting and binding of neurofilaments, including tau proteins

basal forebrain nuclei

disappear in Alzheimer’s due to plaques and tangles

Pathology of Alzheimer’s Disease

• ApoE binds & clears excess amyloid

• if too much excess beta-amyloid, plaques form and make neurofibrillary tangles

• loss of basal forebrain produce acetylcholine

• dementia

hormones

• chemical messengers

• released into bloodstream to circulate into the body

• only act on tissues that have specific receptors

endocrine glands

organs that make and release hormones

autocrine

release chemical that feeds back to itself to regulate

paracrine

group of cells in system that release chemical messenger that only affects nearby cells

endocrine function

make hormone, release it into bloodstream, bloodstream delivers to target organ/receptor for hormonal action

Principles of Hormone Action

1. gradual time course - hours to weeks

• a little goes a long way, gene transcription/translation occurs

2. Changing intensity/probability of behavior

• does not direct behavior, more like a dimmer switch

3. type and amount of hormone depends on environment

• reciprocal relationship

4. each hormone has multiple effects on various tissues, organs, and behaviors

• diametrically opposed actions on the same organ are possible

5. produced in small amounts & secreted in bursts

6. levels vary rhythmically during the day

7. hormones interact with other hormones

8. chemical stricture may be similar across species but function may vary

9. can only affect cells that have specific receptors for that hormone

protein horomones

• hormones made of long aa chains

• FSH, LH, TSH, GH, prolactin, insulin, oxytocin, vasopressin

• protein receptors embedded into plasma membrane that activate 2nd messengers

amine hormones

• hormones made of a N-H group

• epi, norepi, melatonin

• protein receptors embedded into plasma membrane that activate 2nd messengers

steroid hormones

• gonadal hormones

• cortisol (glucocorticoid)

• lipid soluble, pass directly into membrane, interact with intracellular steroid receptors → change gene transcription

autocrine feedback

• endocrine cell makes & releases hormone

• makes target cell

• endocrine cell says '“enough”

• shuts down until needed again

target cell feedback

• endocrine cell makes hormone

• makes effect on target cell

• target cell makes secondary biological response that feeds back onto endocrine cell to

• shuts endocrine cell down

brain & pituitary regulation

• hypothalamus has releasing hormones—neurons that release hormones into blood stream by pituitary gland

• activates & releases tropic hormone

• tells other glands to make & release their main hormone

• released to target cell

• response

• hypothalamus, pituitary gland, and double-mechanism shuts down hormone release

pituitary gland

primary hormone is oxytocin

oxytocin

• primary hormone of pituitary

• milk-letdown reflex

• bond between mom & child

milk-letdown reflex

1. nerve impulse to brain to release oxytocin

2. causes cells of mammary glands to contract/milk release, baby continues suckling

posterior pituitary gland

neurohypophysis & hypothalamus axons extend to posterior pituitary, make and release hormones that release directly into the local bloodstream —> body

anterior pituitary gland

adenohypophysis; neurons shorted axon, pump hormone into local blood supply and corticotropic releasing hormones direct pituitary cells to release trophic hormones

GNRH

• releasing hormone of hypothalamus

• release LH & FSH tell cells to release sperm & egg