cell bio and neuroscience exam #4

RT-PCR

• micro punch specific brain areas, can extract and analyze RNA or proteins. only one gene of interest at a time

• RT-PCR studies show inflammatory cytokines in greatest amounts one day post injury

immunohistochemistry

using antibodies conjugated to a fluorescent marker that leads to a color change. used to identify specific cells and the proteins they express

lesions and electrophysiology studies

used to gather information about brain areas in live, intact animals to study behavior

pre limbic cortex (locate)

fear expression, risk-reward decisions, involved in anxiety-like behavior

dentate gyrus (locate)

part of hippocampus. Learning and memory, neurogenesis

reticular substantia nigra (locate)

movement control, dopamine neurons degenerate here in Parkinson’s disease

periaqueductal gray (locate)

descending pain modulation, autonomic function, motivated behavior

dorsal raphe nucleus (locate)

source of serotonin, descending modulation of pain

putamen (locate)

modulates upper motor neurons for descending motor control. degenerates in Huntington’s disease

ventral tegmental area (locate)

regulates dopamine— reward, motivation, addiction

nucleus accumbens (locate)

regulation of motivated behaviors, reward, pleasure, addiction

cryostat

used for sectioning brain tissue

superior

above

inferior

below

anterior

in front of

posterior

behind

dorsal

upper/back

ventral

lower/below

coronal

frontal (hamburger)

saggital

axial (hot dog)

subdivisions of the spinal cord (top to bottom)

• cervical

• thoracic

• lumbar

• sacral

• coccygeal

frontal lobe

central sulcus

parietal lobe

occipital lobe

temporal lobe

frontal lobe brain regions

primary motor cortex, premotor cortex, prefrontal cortex, Broca’s area

parietal lobe brain regions

primary somatosensory cortex, wernicke’s area

occipital lobe brain regions

primary visual cortex, primary auditory cortex

midbrain

structures include substantia nigra and periaqueductal gray

pons

relay center

medulla

• autonomic reflex center

• cardiovascular center

• respiratory centers

hypothalamus

• ANS

• sleep/wake

• hunger and satiety, body temp

• physical response to emotions

pons

medulla

thalamus

midbrain

hypothalamus

corpus callosum

lateral ventricle

thalamus

relay center, gateway to the cortex

lateral ventricle

stores CSF

hippocampus (learning and memory)

corpus callosum

white matter tract that divides the left and right hemispheres

white matter

axons

gray matter

cell bodies

corpus callosum

amygdala

thalamus

lateral ventricle

blood brain barrier function

facilitates what enters the brain— drugs, pathogens, bacteria, viruses

disruptions to the blood brain barrier

can be caused by head trauma, disease, toxins, infection, and stress

result of the blood brain barrier being compromised

infection, inflammation of the brain. unique brain environment would be disrupted, brain factors entering periphery

CSF functions

shock absorption, nourishment, protection, waste removal, brain buoyancy

ventricular system

distributes CSF throughout the brain

dura mater

arachnoid mater

pia mater

chloroid plexus of lateral ventricle

neuronal development (concepts/processes)

cell proliferation, cell migration, cell differentiation, process outgrowth

gastrulation

• local invagination of a subset of cells in the very early embryo. once complete, the embryo consists of 3 layers of cells called germ layers (ectoderm, mesoderm, endoderm).

• gastrulation defines: midline, anterior-posterior axes, dorsal-ventral axes

notochord

• transient structure that forms at the midline of the gastrulating embryo; central event for nervous system development

• sends inductive signals to the overlying ectoderm to cause a subset of cells to differentiate into neuralectodermal precursor cells

neurulation

formation of neuralectodermal cells.

• neural plate forms as a result of the thickening of neural ectoderm

• neural tube later forms as result of neuronal plate infolding— gives rise to brain, spinal cord, and most of PNS

neural plate

forms on the ectoderm above the notochord, develops into neural tube

neural crest

after 20 days, begins to form within the neural plate/tube. after 22 days, cells of neural crest are separate from complete neural tube

neural tube

develops in later stages of neurulation. its roofplate and floorplate send location-dependent signals

neuroectodermal precursor cells/neural stem cells

undifferentiated cells with the capacity to divide to produce more precursor cells, or differentiate into any type of cells found in nervous tissue (i.e. astrocytes, microglia, neurons, etc.)

transient structures in neurulation

notochord, floorplate, roofplate. provide signals to developing neural tube, and disappear once initial nervous system development is complete

neural crest cells

arise from the lateral edges of the neural plate as the neural tube forms, migrate away from neural tube and give rise to a variety of progeny (not CNS; portions of the PNS)

structures derived from neural crest cells

• neurons and glia of the sensory and autonomic ganglia (outside CNS)

• neurosecretory cells of the adrenal gland

• neurons of the enteric nervous system (GI tract)

• non-neuronal structures: pigment cells beneath epidermis, cartilage, and bone (particularly face and skull) to support and protect brain

populations of neural crest cells

different migratory patterns

i. cranial

ii. vagal

iii. trunk

iv. sacral

cranial neural crest cells

cranial sensory ganglion, non-neural cells that become the cranial skeleton, thyroid gland, and teeth

vagal neural crest cells

enteric nervous sytem. Vagus nerve connects brain & gut

trunk neural crest cells

dorsal root ganglion

sacral neural crest cells

additional neurons of the enteric nervous system and posterior ganglion of the sympathetic chain

neural stem cell

gives rise to more stem cells, or full range of differentiated cell types in CNS & PNS

neural progenitor cell

can proliferate, but can only generate one class of differentiated progeny.

ES cells

embryonic stem cells, derived from pre-gastrula embryos. Can give rise to all tissues and cell types, proliferate more than neural stem cells and neural progenitor cells

IPSCs

induced pleuripotential stem cells. inducing differentiation of somatic cells with stem cells via transcription factors. regenerative potential for tissue repair

why experiments where neural stem cells are transplanted into the adult brain are unsuccessful

transplanted neural stem cells lack signals for differentiation and migration

formation of major brain subdivision

following formation of the neural tube, beginnings of major brain regions start to appear with bending, folding, and constriction of the neural tube

initial subdivisions of the neural tube into primitive brain regions

• prosencephalon— forebrain

• mesencephalon— midbrain

• rhombencephalon— hindbrain

prosencephalon

• telencephalon — cerebral cortex, hippocampus, and basal ganglia

• diencephalon— thalamus and hypothalamus; optic cups — retina

mesencephalon

superior and inferior colliculi and midbrain tegmentum (ventral portion, substantia nigra)

rhombencephalon

• metencephalon— cerebellum and pons

• myelencephalon— medulla

inductive signaling

Molecular signals are secreted by one embryonic cell class and tissue and then diffuse and act on adjacent cell class or tissue (i.e. roofplate, floorplate). graded effects (based on distance from source of signal) and more specific effects

neural induction

gene expression, shape, and motility are changed in target cells after inductive signals bind to their receptors

major inductive signaling pathways in vertebrate embryos

turns on transcription factors for genes in the nucleus. signals can act on intracellular or extracellular receptors to cause a signaling cascade that activates transcription factors

ventricular zone

precursor cells located at the innermost cell layer surrounding the lumen of the neural tube. neural precursor cells undergo mitosis within ventricles, then migrate to cortex.

symmetrical divisions in ventricular zone

generates two neural stem cells

asymmetrical divisions in ventricular zone

generates a neuroblast (becomes a differentiated neuron) and a progenitor

neurogenesis

begins after initial patterning of brain is complete, occurs before birth (precursors disappear after birth, no way to replace lost neurons)

molecular and cellular mechanisms that guide neuronal and glial differentiation

excitatory signals induce cell differentiation

migrating neurons

guided by radial glia

reelin

neurotransmitter that guides radial glial migration. mutation leads to decreased brain tissue, enlarged ventricles from degeneration due to improper migration

lisencephaly (DCX)

enlarged ventricles, smooth brain (less surface area)

developmental disorders

spina bifida, anencephaly. from neural tube defects resulting from folic acid deficiency

retinoic acid

signaling molecule, alters gene expression of SHH leading to birth defects

medullablastoma

neurodevelopment disorder associated with SHH mutation. keeps some cells as precursors while others divide uncontrollably due to lack of SHH-mediated regulation of the Gli1 transcription factor

cell proliferation

stem cells into progenitors or more stem cells