NEURO 3000 EXAM 3

cerebrum

two hemispheres that receive input contralaterally

cerebellum

large structure of hindbrain that controls fine motor skills

- ipsilateral (same)

brainstem

regulates body temp, breathing, and consciousness

- essential for life (relay center)

spinal cord

conducts sensory and motor nerve impulses to and from the brain

- spinal nerves part of PNS

pyramidal decussation

motor fibers from the medulla cross the midline; continue into spinal cord as corticospinal tract

sagittal section

divides the body into left and right parts

coronal/transverse section

divides body into front and back

horizontal section

divides body into upper or lower sections

gyri

ridges of the brain

sulci

valleys between ridges

fissure

deep groove; deeper than sulci

- major divisions (left & right hemis, cerebrum from cerebellum)

grey matter

unmyelinated neuron cell bodies (cortex; superficial)

white matter

myelinated axons

nucleus

mass of neurons; usually deep in brain (deep cerebellar nucleus, etc.)

dorsal roots

sensory input to cord

ventral roots

motor neuron axons that exit the spinal cord

ganglion

collection of nerve cell bodies in the PNS

somatic nervous system

division of PNS that controls the body's skeletal muscles; voluntary movements

- cell body of motor neurons in CNS, axons in PNS

autonomic nervous system

controls involuntary actions

- mostly smooth muscles, heart muscles, and glands

sympathetic preganglionic neurons

originate in thoracic and anterior lumbar regions of spinal cord

parasympathetic preganglionic neurons

originate from various anterior cranial nerves and posterior sacral regions

internal capsule

white matter tract that carries outgoing fibers from cortex, and incoming from thalamus to cortex

postganglionic neurons PNS

project to glands

cleavage to blastocyst stage

2-10 days post fertilization

neural induction

gastrulation; days 11-15

- embryo cells move and form 3 germ layers

- mesoderm is formed & induces neurectoderm to neural fate by noggin

somites

generate bone and muscle related to spinal vertebrae

- generated from mesoderm

neural tube formation

neurulation; 16-25 days

- neural tube becomes brain and spinal cord

- neural crest become sensory and autonomic neurons, etc.

regionalization/patterning

28+ days; formation of brain vesicles (become forebrain, midbrain, hindbrain)

- AP and DV patterning

anterior posterior patterning

forebrain, midbrain, hindbrain, spinal cord

- controlled by retinoic acid

dorsal-ventral patterning

determines ventral and dorsal cell types

- controlled by sonic hedgehog, shh

notochord

becomes part of bone and muscle in spinal cord

- releases shh

sonic hedgehog

ventralizing signal

neurogenesis

proliferation, migration, differentiation

- at first, symmetric cell division of radial glia, then asymmetric after

day 36

forebrain expands & adds telencephalic vesicles

- hindbrain develops into metencephalon and myelencephalon

days 49-90

forebrain develops into diencephalon and telencephalon

forebrain

telencephalon and diencephalon

- perceptions, awareness, cognition, voluntary action

midbrain

mesencephalon

hindbrain

metencephalon and myelencephalon

- dorsal becomes cerebellum, ventral becomes pons

- medulla

- 4th ventricle

telencephalon

cerebral cortex, basal ganglia, hippocampus, lateral & 3rd ventricles

Diencephalon

thalamus and hypothalamus, part of 3rd ventricle

Mesencephalon

tectum, substantia nigra, cerebral aqueduct

Metencephalon

pons and cerebellum

Myelencephalon

medulla

cortical neurons

send axons back to brainstem through internal capsule, project on corticospinal tract, or project to basal ganglia (includes substantia nigra)

tectum

the dorsal part of the midbrain; includes the superior (visual) and inferior (auditory) colliculi

Tegmentum

The ventral part of the midbrain; VTA, substantia nigra

cerebral aqueduct

connects the third and fourth ventricles

pons

connects cerebral cortex to the cerebellum

medullary pyramids

carry corticospinal projections towards spinal cord

symmetric division

generate more radial glia that divide

asymmetric division

generates one postmitotic (farthest from ventricle) and one precursor

- postmitotic cell migrates and becomes neuron or glia

inside out development of cortex

cells that form each layer migrate past the ones that preceded them

- deeper layers diff into pyramidal neurons

- intermed. zone becomes white matter

- VZ disappears

differentiation

postmitotic precursor reaches destination & differentiates into neuron w/ dendrites and axon

semaphorin 3A

guidance molecule expressed in marginal zone

- dendrites attracted & axon is repulsed by (responsible for polarity of pyramidal cell)

synaptogenesis

formation of synapses

target dependent cell death

more neurons are generated than are actually needed

synaptic pruning

the elimination of neurons as the result of nonuse or lack of stimulation

- microglial role

frontal lobe

planning, organization, impulse control, decision making

- primary motor cortex (voluntary); caudal

- Broca's area

temporal lobe

language, hearing, memory

- auditory cortex

- wernicke's area

- ventral stream: what pathway

parietal lobe

receives sensory input for touch and body position

- primary somatosensory cortex; rostral

- dorsal stream: where pathway

occipital lobe

visual processing

corpus callosum

band of neural fibers (white matter) between brain hemispheres and carries info

thalamus

receives info from sensory systems and relays to cortical areas

hypothalamus

controls emotion and motivated behaviors; homeostasis

- has control of pituitary gland

meninges

three protective membranes that surround the brain and spinal cord

subarachnoid space

a space in the meninges filled with CSF supplied from ventricles

- CSF in space can be absorbed by blood vessels

ventricles

hollow inferior of NS filled with CSF

CSF

produced by choroid plexus in ventricles, exits ventricular system through apertures, and enters subarachnoid space

ventricular system

CSF comes from arterial blood, and removed by venous system

MRI

general brain structure (static)

DTI

scans water movement (static)

- white matter tracks

PET scan

identifying functional brain regions

- 2DG, measures metabolic function; correlates with electrical activity

fMRI

ability to detect changes in blood flow

- detect changes in brain regions among patients

tastants

chemicals that stimulate gustatory receptor cells

papillae

taste buds

- not true neurons

- detect chemicals in food at microvilli that project into taste pores

- constantly replaced (basal cells are precursors)

physiology of taste cells

chemicals cause depolarizing receptor potential; activates Ca2+ to release NT

- usually only respond to only 1 of 5 tastes

sour and salty taste cells

release serotonin

sweet, bitter, and umami cells

release ATP

sour taste mechanisms

Na+ sensitive channels are always open

- generated by acidic foods

sweet, bitter, and umami mechanisms

all GPCRs

- G protein activates PLC, which cleaves PIP2 into DAG and IP3 (2nd messengers)

- IP3 binds to its receptor which releases Ca2+

- Na+ channel depolarizes which releases ATP (ATP channel non-vesicular)

bitter taste receptors

heterodimers of T1R (3) and T2R (25)

sweet taste receptor

heterodimer T1R2 + T1R3

umami taste receptor

T1R1 and T1R3

gustatory sensory neuron cell bodies

cranial nerves 7, 9, 10

- receive input from taste cells, transmitted to cell body, then projects to gustatory nucleus

- ipsilateral system

olfactory epithelium

thin layer of tissue within nasal cavity

- contains the receptors for smell

olfactory receptors

neurons with cilia at one end that receive odorants

- axon projects to olfactory bulb

- expresses one receptor gene, but can bind to multiple odorant MCs

vomernasal organ

detects pheromones (in animals)

- controversial in humans

olfactory signal transduction

1. odorant dissolves in mucus

2. binds to receptor proteins on cilia (GPCR)

3. activates Golf in olf. cells

4. activates adenylyl cyclase, inc cAMP, open channel

5. Ca2+ and Na+ enter & depolarize

6. Cl channels leave cell and enhances depolarize

Axel and Buck

won the Nobel Prize in 2004 for discovering olfactory receptors

olfactory glomeruli

clusters of neurons near the surface of the olfactory bulbs

- bilaterally symmetric

lateral inhibition in olfactory bulb

granule cells in bulb help sharpen mitral cell responses in selected glomeruli

- granule cell: top down inputs

olfactory pathways

olfactory bulb, olfactory tubercle, thalamus, frontal cortex; mediates perception of odors

- olf bulb, primary olf cortex, amygdala (emotional & social behaviors)

sound

vibrations that travel through the air or another medium

frequency

the number of complete wavelengths per second

- pitch

amplitude

the height of a wave's crest

- loudness

tympanic membrane

eardrum

- sound waves move it

ossicles

three tiny bones in the middle ear

- move the membrane at the oval window

- amplify force

oval window

membrane at the enterance to the cochlea

- ossicles transmit vibrations

cochlea

tube in the inner ear through which sound waves trigger nerve impulses

- contains 3 fluid filled chambers

- fluid movement causes response in hair cells

organ of corti

contains hair cell and primary auditory nerve fibers

- hair cells arranged along basilar membrane

- have stereocilia projecting into endolymph