neurotransmission, neurochemistry, and neuroanatomy

Afferent

receiving information, towards cell body

Efferent

sending information, away from cell body

Active zone

where neurotransmitter vesicles bind to then release their content into the cleft

PSD

postsynaptic density, high density of receptors

what happens to postsynaptic potential when a anion enters?

it becomes inhibitory postsynaptic potential

cholinergic type

ACh

what is Acetacholine (ACh) inactivated by?

- Inactivated by enzymatic degradation: byproducts cannot be used to become the neurotransmitter again

what happens to postsynaptic potential when a cat ion enters?

it becomes an excitatory postsynaptic potential

what do acetocholyine receptor do when associated with ligand gated ion channels?

responsible for neurotransmission, allows ions to travel through membrane

Catecholinergic types

NE - norepinephrine

Epi - epinephrine

DA - dopaminergic

where is NE - norepinephrine mainly found?

- Cell bodies located on locus coeruleus

whats another name for Epi - epinephrine?

- Adrenaline

what is the first system of DA - dopaminergic?

- Its called the mesolimbic DA system:

starts in the cell bodies in VTA (ventral tegmental area), and it controls motivation, which affects behavior

Serotonergic type

serotonin (5-HT)

what is serotonin (5-HT) inactivated by?

- Inactivated by reuptake

Amino acidergic types

glutamate and GABA

Glutamate

- excitatory NT

- EPSP - excitatory post synaptic potential; stimulates an AP, depolarizes neuron

- Bind to ligand gated ion channels - directly change the electrical state of a neuron, broken down by biotransformation

- "True" neurotransmission

GABA

- inhibitory NT

- ISPS - inhibitory post synaptic potential

- Prevents an AP, prevents threshold from being reached, hyperpolarizes neuron

- Bind to ligand gated ion channels - directly change the electrical state of a neuron, broken down by buotransformation

- "True" neurotransmission

Ligand-gated ion channels

- NT binding receptor opens an ion channels

- Inotropic = ions move

- Rapid onset, but a short duration of effects, usually one to neuron to one other neuron

EPSP

cell becomes depolarized (postive ions move in or negative ions move out), an AP is more likely to occur, Na+ moves in cell

IPSP

cell becomes hyperpolarized (negative ions move in or positive ions move out), Cl- moves in or K+ moves out

G-Protein-coupled receptors

- Metabotropic effect

i. NT binding receptor activates a G-protein

ii. Intracellular (second) message is created

iii. Second messenger alters neuronal function (modulation)

iv.Slow

- But, the duration of the effect is longer: mood, motivation, tiredness, usually from one neuron to multiple other neurons (so it can affect a whole structure)

Firing rate

# of APs over time

Summation

the combining of graded potentials/depolarizations from presnayptic APs to reach sufficient threshold in the postsynaptic neuron

Spatial summation

multiple APs from separate nuerons arrive simultaneously at the same postsynaptic neuron, their graded responses combine to reach threshold

Temporal summation

two or more APs arrive very close together at the postsynaptic cell from the same presynaptic neuron, first AP causes depolarization for a few milliseconds, second AP arrives to postsynaptic before its resting membrane potential returns to resting value, graded potentials combine to reach threshold

rostral

anterior

caudal

posterior

dorsal

superior

ventral

inferior

Ipsilateral

Structures localized to the same side

Contralateral

Structures localized to different sides

Nucleus

in CNS, large area of cell bodies with clear boundaries

Locus

in CNS, small are of cell bodies with clear boundaries

Substantia

in CNS, large area of cell bodies with no clear boundaries

Ganglia

in PNS, collection of cell bodies in a defined area

Cortex

- Primarily cell bodies

- Surface of the brain

- Cell bodies are not myelinated, so the cortex is grey matter

- About 10% of the brain

Fiber

- White matter

- One singular, myelinated axon

Tract

- white matter

- Collection of fibers that start at one structure and terminate at one common structure

Bundle

- White matter

- A collection of fibers that pass through the same region, but do not start and end at the same spots

Commissure

- White matter

- A type of bundle that is contralateral; goes from one brain hemisphere to the other

Nerve

- White matter

- Axon bundles in the PNS

- Nerves = PNS only (neurons = CNS)

CNS

i. Brain

ii.Spinal cord

PNS

Everything outside spinal cord

Grey matter

lacks myelin, made up of cell bodies, makes up cortex (outside of brain)

Whiter matter

contains myelin, made up of axons, inside of brain

Gyri

parts of the brain folds that rises

Sulci

part of the brain fold that go in, the grooves

Fissure

a deep sulcus

Lateral sulcus

divides frontal and temporal lobes, dorsal from ventral

Central sulcus

divides frontal from parietal lobes, anterior and posterior

Parietoccipital sulcus

separates parietal from occipital lobe

Superior longitudinal sulcus

separates the two brain hemispheres

Frontal lobe

high cognition

Parietal lobes

somatic (senses)

occipital lobe

sight

Temporal lobes

hearing, many other diverse functions

Cortex Layer 1

molecular layer, no cell bodies, only synapses + dendrites of other neurons to receive and send info

Cortex Layer 2 + 3

function together, pyramidal cells, its axons go to other cortical areas, receive and send information from toher parts of the cortex

Cortex Layer 4

stellate (star shaped) cells, sends information between the cortext and thalamus

Cortex Layer 5 + 6

function together, pyramidal cells, axons go to other parts of the brain (noncortical), receive and send information from other parts of the brain

Cortex circuitry is ...

columnar, meaning that the info that leaves the cortex integrates all the information from that column (vertical) of neurons (as opposed to horizontal rows)

Dicencephalon components

thalamus, hypothalamus, epithalamus

Thalamus

- A relay

- All ascending and descending information goes here first, undergoes some low level processing, and then is sent to the proper part of the cortex or another structure

Hypothalamus

- Indirectly controls the endocrine system because it controls the pituitary gland

- Controls visceral states: the states of organs

- Ex: hunger, blood pressure, thermoregulation; all unconscious/Automatic

- Primtive emotion: largely suppressed in humans, predatory and territorial aggression in animals, usually only occur in humans with use of drugs (ex: some people are aggressive when drunk)

Epithalamus

-Secretory, epithelial cells

- Pineal gland: an endocrine gland, secretes melatonin which regulates circadian rhythm

- Choroid plexus: creates cerebrospinal fluid (CSF)

cerebellum

- Integrates sensory and motor information, makes motor maps

- Exacts control over movements

- No direct access to motor neurons: has to send info to cortex which sends to lower motor neurons

brainstem components

midbrain, pons, medulla

midbrain

- Procesing of visual and auditory information

- Contains the DMS

Pons

Relay, creates a connection between the cerebellum and cerebrum

Medulla

- Visceral motor muscle functioning

- Muscles are controlled at an unconscious level: breathing, blood pressure, cardiovascular function

- Primitive brain reflex: sneezing, vomitting, yawning, hiccups

modulation

changes general state of neuron, imposes it on the brain, ex: sleeping

translation

changes electrical state of neuron

enzygamatic degradation

byproducts that can't become NTs again

biotransformation

inactive byproducts -> reactivated once returned to cell

reuptake

NTs pumped back into presnynaptic neuron -> repackaged -> reused (not modified)

diffusion (as form of neurotransmitter inactivation)

diffuses to the point where NT is too low top bind the receptors, usually occurs with g-protein receptors because they involve complex circuits; large area where the NTs can move

precentral gyrus

primary motor cortex

postcentral gyrus

primary sensory cortex

what is NE norepinephrine main function?

- Function in arousal and sleep

how is NE norepinephrine inactive?

- Inactivated by reuptake

What receptors do NE-norepinephrine bind to?

Receptors = g protein-coupled receptors (modulation)

why is epi- epinephrine considered a hormone?

its released from the medulla into the bloodtream, acting a a hormone that affects many organs.

where is epi- epinephrine found and whats its function?

In CNS for modulation function. Adrenomedulla releases epinephrine during sympathetic NVS into blood stream

how is epi-epinephrine inactivated?

inactivated by reuptake

which type of receptors are epi-epinephrine associated with?

Receptors = g protein coupled receptors (modulation)

what is the 2nd system of DA- dopaminergic?

its called the basal ganglia dopamine system: controls movement

what is the primary function of DA-dopaminergic?

controls movement and associated with motivational behavior

what happens if theirs a lack of DA-dopaminergic?

parkisons disease

how is DA-dopaminergic inactivated?

by reuptake

what receptors is DA-dopaminergic associated with?

G protein coupled receptors

what type of receptors are serotonin (5-HT) associated with?

- G - protein-coupled receptors (modulation)

what is the primary function of serotonin (5-HT)?

- Modulate mood and affect

what are SSRI’s and what do they do?

- they are selective serotonin reuptake inhibitors and they block reuptake to treat depression

where is serotonin (5-HT) found?

- Location = raphe nuclei located in the midline of the brainstem

whats a another name for G protein coupled receptors?

neuromodulartransmission (slow onset and long duration)

diffuse neuromodullary system?

function is neuro-modulation