Behavioral Neuroscience Unit 1 Exam

neuroscience

study of brain; understand how nervous systems function

CNS

consists of Brain (cerebrum, cerebellum, brain stem and retina [eye]) & Spinal Cord

PNS

consists of bundles of nerves that connect the senses + organs of body to CNS

cerebrum

largest part of the human brain, associated with higher brain function such as thought and action (sensation + perception); repository of memory

brain

an organ of soft nervous tissue contained in the skull of vertebrates functioning as the coordinating center of sensation and intellectual and nervous activity

spinal cord

long, tube-like band of tissue that connects brain to your lower back & carries nerve signals in both directions

brain stem

bottom part of brain that connects rest of brain to spinal cord; send signals from brain to rest of body; responsible for subconscious body functions, like breathing & maintaining your heart rate

ventricles

hollow spaces in brain with fluid (cerebrospinal fluid)

white matter

nerve bundles that connects areas of gray matter; mostly axons + has myelin sheath (contains fatty acids - fatty tissue appears whiter and non fatty tissue appears darker)

grey matter

has cell bodies of neurons primarily that allows you to function

neuron

excitable cells of the nervous system that sense environment, communicate with each other, and assemble into circuits to perform specific function

glia

a category of cells that support neurons, provide nutrients and clear waste products, insulate neurons from each other (or the body), guide neural development, and act as the immune system for the brain. Way more of these neurons

histology

microscopic study of the structure of tissues.

golgi stain

makes a small percentage of neurons become darkly colored in their entirety, revealing the neuronal cell body is actually only a small fraction of total structure of neuron; helped identify parts of neuron

cell body / soma / perikarya

swollen region containing cell nucleus

neurites

thin tubes that radiate away from soma

dendrites

tree like processes that receive inputs from nearby cells

axon

wire-like projection that sends information to other cells

terminal button

site where axon comes in contact with other neurons (or other cells) and passes information on to them; contain synaptic vesicles filled with neurotransmitters

dendritic spines

specialized structures that cover dendrites of some neurons which receive some types of synaptic input; believed to isolate various chemical reactions that are triggered by southwest of synaptic activation

axon initial segment

axon extends from the cell body beginning at the axon hillock

axon hillock

region where axon & action potential begins, which tapers away from soma to form initial segment of axon proper

receptor

specialized protein molecules that detect neurotransmitters in synaptic cleft

synapse

point of contact for axon to other neurons that allows passage of information

synaptic vesicles

small bubbles of membrane in terminal

microtubules

large, straight, thick-walled hollow pipes that run longitudinally down neurites that help determine cell shape + help with cell movements

myelin

insulating layer, or sheath that forms around nerves made up of protein & fatty substances that allows electrical impulses to transmit quickly + efficiently along nerve cells

node of Ranvier

short length where myelin sheath is interrupted & axonal membrane is exposed

action potential

rapid sequence of changes in the voltage across a membrane that conveys information

excitable membrane

cells capable of generating + conducting action potentials are said to have this

ex. nerve + muscle cells

resting membrane potential

difference in electrical charge (voltage difference) between neuron’s cytosol & extracellular fluid

equilibrium potential

electrical potential that exactly offsets the driving force caused by the concentration gradient

ions

atoms or molecules that have a net electrical charge

cations

ions with a net positive charge

anions

ions with a negative charge

phospholipid bilayer

stable arrangement in which hydrophilic heads face outer & inner watery environments + hydrophobic tails face each other → effectively isolates cytosol of neuron from extracellular fluid

ion channels

macromolecular pores embedded in cell membranes that catalyze the flux of ions across cell membranes, and play fundamental roles in a wide variety of functions throughout the body

ion pumps

assemblies of integral membrane proteins that modulate ion transport into and out of a cell or organelle, leading to generation of electrical signals

membrane potential

voltage across neuronal membrane at any moment (Vm)

electrode

technology used to record electrical signals from neurons & also used to stimulate neurons

ionic driving force

difference between real membrane potential & equilibrium potential (Vm - Eion)

capacitance

a membrane that is said to store electrical charge

rising phase

first part of action potential characterized by a rapid depolarization of membrane where change in membrane potential continues until Vm = 40 mV; influx of sodium ions into cell which causes membrane to depolarize

overshoot

part of action potential where inside of neuron is positively charged with respect to outside (action potential at peak here); voltage-gated sodium ion channels close & voltage potassium channels open allowing potassium ions to flood out of cell; once potassium flowing out, calcium voltage-gated ion channels open & calcium flows into cell

falling phase

rapid repolarization until inside of membrane is actually more negative than resting potential; potassium ions are flowing out of cell & calcium ions are flowing in, but become inactive at end of this phase

undershoot / after-hyperpolarization

last part of falling phase where membrane potential is more negative than resting membrane potential until voltage-gated potassium channels close; hyperpolarization occurs because there’s very little sodium permeability

threshold

critical level of depolarization that must reached in order to trigger an action potential; when voltage-gated sodium channels open

absolute refractory period

period when it is impossible to generate another action potential after an action potential has been initiated

relative refractory period

period after absolute refractory period when it can be relatively difficult to initiate another action potential for several milliseconds, during this period amount of current required to depolarize neuron to action potential threshold is elevated above normal (more depolarization current required)

voltage clamp

tool used to measure ion currents through the membranes of excitable cells; can deduce changes in membrane conductances that occur at different membrane potentials by measuring currents that flowed across membrane

patch clamp

tool used to study ionic currents pass through individual ion channels; entails sealing tip of an electrode to a very small patch of neuronal membrane, this patch can then be torn away from neuron & ionic current across it can be measured as membrane potential is clamped at any value experimenter selects

channelopathy

human genetic disease caused by alteration in structure + function of ion channels

voltage-gated sodium channel

protein forms a pore in membrane that is highly selective to Na+ & pore is opened + closed by changes in membrane voltage; is closed at negative resting membrane potential & when membrane is depolarized to threshold molecule twists into a configuration that allows passage of Na+ through pore

voltage-gated potassium channel

open when membrane is depolarized & function to diminish any further depolarization by giving K+ a path to leave cell across membrane

sodium-potassium pump

enzyme that breaks down ATP in the presence of internal Na; chemical energy released by this reaction exchanges internal Na for external K; ations of this ensure that K is concentrated inside the neuron and that Na is concentrated outside

saltatory conduction

action potential propagation in myelinated axons where action potentials skip from node to node

synaptic transmission

process of information transfer at a synapse

electrical synapse

electrical current flowing from one neuron to next

chemical synapse

chemical neurotransmitters transfer information from one neuron to another at synapse

gap junction

specialized sites where electrical synapses occur

connexon

cluster of special proteins that fill narrow gap of gap junctions

EPSP

transient postsynaptic membrane depolarization caused by ligand-gated ion channels that a pore that passes Na+ or Ca2+

IPSP

transient hyperpolarization of postsynaptic membrane potential caused by ligand-gated ion channels that contain a pore that passes CI- (chloride)

secretory granules

specialized intracellular organelles that serve as a storage pool for selected secretory products that appear dark in electron microscope

synaptic vesicles / dense-core vesicles

small membrane-enclosed spheres that store neurotransmitter, chemical used to communicate with postsynaptic neuron

active zones

sites of neurotransmitter release

postsynaptic density

protein thickly accumulated in & under postsynaptic membrane, which contains neurotransmitter receptors, which convert intercellular chemical signal into intracellular signals in postsynaptic cell

axodendritic

postsynaptic membrane is on a dendrite

axosomatic

postsynaptic membrane is on a cell body

axoaxonic

postsynaptic membrane is on another axon

dendrodendritic synapses

dendrites form synapses with one another

neuromuscular junction

chemical synapse that occurs between axons of motor neurons of spinal cord & skeletal muscle

motor end-plate

postsynaptic membrane that contains a series of shallow folds → chemical synapse between the terminal part of the motor neuron and the target muscle

neurotransmitter

chemical signals released from presynaptic nerve terminals into the synaptic cleft

voltage-gated calcium channels

group of pores that are permeable to calcium → there is a large inward driving force on Ca2+

exocytosis

process by which vesicles release their contents

neurotransmitter receptor

receptors that bind neurotransmitters

transmitter-gated channels (ligand-gated)

receptors consist of transmembrane subunits and an ion channel pore that is opened by the binding of a ligand; fast ion channels (ionotropic)

G-protein coupled receptors

receptors are coupled to intracellular signaling molecules (G-proteins). Ligand-binding at metabotropic receptors initiates biochemical cascades within the cell that have a wide range of functions; slow

second messengers

targets of G-proteins; can activate additional enzymes in cytosol that can regulate ion channel function & alter cellular metabolism

metabotropic receptors

subtype of membrane receptors that do not form an ion channel pore but use signal transduction mechanisms, often G proteins, to activate a series of intracellular events using second messenger chemicals

autoreceptors

presynaptic receptors that are sensitive to neurotransmitter released by presynaptic terminal

agonist

drugs that bind to receptors & mimic actions of naturally occurring neurotransmitter

antagonist

inhibitors of neurotransmitter receptors that bind to receptors & block normal action of transmitter

synaptic integration

process by which multiple synaptic potentials combine within one postsynaptic neuron

quantal event

method of comparing amplitudes of miniature & evoked PSPs, can be used to determine how many vesicles release neurotransmitter during normal synaptic transmission

cholinergic

defined by presence of acetylcholine

noradrenergic

neurons that use amine neurotransmitter norepinephrine (NE)

glutamatergic

synapses that use glutamine

GABAergic

synapses that use GABA

peptidergic

synapses that use peptides

immunochemistry

method for viewing location of specific molecules, including proteins, in sections of brain tissue

in situ hybridization

method for localizing specific mRNA transcripts for proteins; used to confirm that a cell synthesizes a particular protein or peptide

autoradiography

technique for viewing distribution of radioactivity

receptor subtype

each of different receptors a neurotransmitter binds to

nicotinic ACh receptor

a ACh receptor subtype located in skeletal muscle

muscarinic ACh receptor

a ACh receptor subtype located in heart

AMPA

ionotropic receptor for glutamate that mediates fast synaptic transmission in CNS

NMDA

ligand-gated cation channels activated by an excitatory neurotransmitter, glutamate

kainate

ionotropic receptors that respond to the neurotransmitter glutamate