Neuron Communication & Scanning/Stimulation techniques

sodium (Na+)

positively charged ion

higher concentration in extracellular fluid and causes depolarization when entering a neuron

Potassium

positively charged ion

higher concentration in intracellular fluid and is responsible for repolarization when exiting neurons

chloride (Cl-)

negatively charged ion

higher concentration in extracellular fluid, if it enters the cell it causes hyperpolarization

calcium (Ca++)

positively charged ion

higher concentration in extracellular fluid

when it enters a neuron at the synapse, if facilitates exocytosis of neurotransmitters

neuron membrane

surrounds neuron

made up of 2 layers of lipids and large proteins

selectively permeable to molecules and ions

resting potential

difference in millivolts comparing the inside and outside of a neuron

negative on the inside compared to the outside (-70mV)

ion channels

large proteins in the neuron membrane that selectively permit the flow of specific ions into and out of a neuron

voltage-gated

ion channel that opens and closes when the membrane around it reaches a specific polarity

threshold potential

specific membrane polarity that opens voltage-gated ion channels

chemically gated

an ion channel that opens and closes by a chemical such as a neurotransmitter

action potential

temporary reversal of membrane polarity caused by voltage gated ion channels reaching their threshold

this localized polarity change travels down the axon away from the cell body

axon initial segment (AIS)

the segment of an axon just past the axon hillock where an electrical signal (action potential) begins

axon hillock

place where the axon meets the cell body

depolarization

a reduction of membrane potential of a neuron caused by Na+ channels opening and Na+ enters the neuron

repolarization

a process where the polarity of a neuron is restored, caused by K+ channels opening and K+ leaving the neuron

hyperpolarization

increase in polarity of a neuron from the resting potential — reduces the likelihood of an action potential

absolute refractory period

between 1-2 miliseconds after an action potential starts when another action potential cannot be generated

relative refractory period

when the membrane potential is hyperpolarized, making a new action difficult but not impossible to generate

all or none law

the rule that once an action potential starts, it does not diminish in strength

saltatory conduction

in a myelinated axon, it is the bouncing of action potentials from one node of ranvier to the next, increasing the speed of the action potential propogating down the axon

sodium-potassium pump

a process of pulling 3 Na+ ions out of the neuron for every 2 K+ ions that are pumped in

requires ATP for energy

synapse

place where one neuron communicates with another neuron

axodendritic

when an axon from one neuron communicates with the dendrite of another neuron

axosomatic

when an axon from one neuron communicates with the soma (cell body) of another neuron

axoaxonic

when an axon from one neuron communicates with the axon of another neuron

dendritic spines

small protuberances that are along the dendrites

often meet terminal boutons of axons from other neurons to form a synapse

electrical synapse

a connection between two cells where they are physically connected and cytoplasm can flow between gap junctions

gap junctions

in an electrical synapse, the place where two neurons are attached to one another to allow the flow of molecules and ions between them through connexons

connexon

an assembly of six proteins embedded in a neuron membrane that forms a pore

__ from two neurons connect to form a large channel between them

chemical synapse

a type of synapse where the terminal bouton of one neuron communicates with another neuron, but the neurons do not touch

synaptic cleft

a tiny space between the terminal bouton on the presynaptic cell and the post synaptic cell

exocytosis

the release of neurotransmitters when a vesicle fuses with the membrane of a terminal button

process is inititated by Ca++

ionotropic receptor

a neurotransmitter that opens in channels directly

metabotrophic receptor

a neurotransmitter receptor that affects an ion channel through a second messenger system

neurotransmitter

chemical messengers released from vesicles in presynaptic cells that act as keys on postsynaptic cells

excitation

when a neurotransmitter increases the likelihood of an action potential on the postsyaptic neuron

inhibition

when a neurotransmitter reduces the likelihood of an action potential on the post synaptic neuron

excitatory postsynaptic potential (EPSP)

when a postsynaptic neuron depolaries, increasing the likelihood of an action potential

inhibitory postsynaptic potential (IPSP)

when a postsynatpic neuron hyperpolarizes or is prevented from depolarizing, decreasing the likelihood of an action potential

spatial summation

the additive influence on action potentials of EPSPs and IPSPs generated at different locations on the neuron

temporal summation

the additive influence on action potentials of EPSPs and IPSPs occuring in rapid succession

summation

the combined influences of EPSPs and IPSPs that determine the rate of action potentials

graded potentials

has levels of strengths that can ultimately influence the production of an action potential

axoplasmic transport

process by which vesicles are moved down the axon along microtubles

agonists

chemicals that help a neurotransmitter function

antagonists

chemicals that hinder a neurotransmitter from functioning

electrocardiogram (ECG)

a noninvasive device to measure heart activity including heartbeats, heart rate, and heart rate variability (variation of time between beats)

electrodermal activity (EDA)

measure of slight perspiration on the skin as an indication of arousal

electromyography (EMG)

a measurement of muscle contraction

X-rays

transmitted through the skin but are absorbed by other tissue and so can give a two dimensional image of the body, including the brain

CT scans

a scanning method that combines several X ray images with the help of computer analysis to make detailed images that can be rendered in 3D

electroencephalograpy (EEG)

method for recording the electrical activity of the cerebral cortex by place electrodes at specific locations on the scalp

continuous recordings

type of EEG research that looks at brainwaves for an extended time

used in sleep research

event related potential (ERPs)

research using an EEG that looks at specific brain that are time-locked to particular cognitive or motor events

magnetic resonance imaging (MRI)

an imaging method that uses large magnets and radio waves to create images of the brain

functional MRI (fMRI)

type of MRI that can create 3D images of the brain highlighting specific areas that are active

BOLD contrast imaging

an fMRI technique that tracks blood flow and so is an accurate measure of increased and decreased brain activity

diffusion tensor imaging (DTI)

an imaging technique that uses special MRI scans and computer software to map the diffusion of water molecules in brain tissue

PET scan

an imaging method that uses injected radioactive isotopes coupled with specific molecules

can look at the active brain

magnetoencephalography

a new imaging technique that maps preceise brain activity by recording magnetic fields

transcranial direct current stimulation (tDCS)

an instrument that applies low frequency electrical stimulation to specific areas of the brain

can imporve memory and attention

may reduce symptoms of depression

transcranial magnetic stimulation (TMS)

this applies magnetic fields to the brain dampening the activity of specific areas

deep brain stimulation (DBS)

method for surgically implanting electrodes into localized areas of the brain

may help with severe depression, Parkinson’s disease, and epilepsy

biofeedback

method for learning to control the body and processes that typically out of conscious control

uses physiological monitors and principles of associative learning