Neuro Exam 1 Flashcards

All of the following are used to observe cellular structure except

-Microtome for tissue slicing

-Golgi stain

-Light microscopes

-hardening tissue in formaldehyde

-all of the above

All of the following are used to observe cellular structure except

-Microtome for tissue slicing

-Golgi stain

-Light microscopes

-hardening tissue in formaldehyde

-all of the above

all of the above

temporal summation

Functional homology

Shared behavioral functions associated with a particular brain region

- the mouse basal ganglia is so similar to the human basal ganglia so we can use a mouse basal ganglia for experimentation to see how any manipulation of the basal ganglia would affect human brains

GABA receptor activation usually has a ________ effect on the post synaptic cell

hyperpolarizing

Benzodiazepines bind to a ___________ site than GABA, causing a _______ in the receptor’s response to GABA binding

different, increase

which of the following provided early evidence for compartmentalization of function in a cerebral cortex? check all that apply

-Localized brain lesions in clinical patients were associated with specific behavioral problems

-Stimulation of a small area of the cortex produced movements in particular limbs

-Measurements of brain folding and size correlated with particular behavioral traits

-All of the above

-Localized brain lesions in clinical patients were associated with specific behavioral problems

-stimulation of a small area of the cortex produced movements in particular limbs

The part of a neuron that receives input signals from other neurons is called the ________ and the part that transmits outputs is the ________

dendrite, axon

Which of the following cell types is most likely to transmit signals between areas of the brain for language and vision?

-Stellate cells

-Glial cells

-Pyramidal cells

-All of the above transmit signals

pyramidal cells

Which of the following factors does not contribute to cell type diversity in a given individual?

-Differences in DNA across neurons

-Differences in gene transcription across neurons

-Differences in ion channel types across neurons

-Differences in dendrite shape across neurons

-All of the above contribute to cell type diversity

-Differences in DNA across neurons

All of the following are neurons except:

-Pyramidal cells

-Stellate cells

-Glial cells

-All of the above are neurons

All of the above are neurons

Neuron degeneration in Huntington’s Disease results from:

check all that apply

-A dysregulation of gene transcription

-An abnormal nucleotide sequence

-A repetition of a particular amino acid in a polypeptide

-All of the above

-An abnormal nucleotide sequence

-a repetition of a particular amino acid in a polypeptide

Where in a neuron does gene transcription occur?

-Nucleus

-Extracellular fluid

-Dendrites

-All of the above

Nucleus

Which of the following occurs during gene transcription?

-DNA moves from the nucleus to the cytoplasm

-DNA is converted into mRNA

-Nucleotides are linked to form polypeptides

-All of the above

DNA is converted into mRNA

All of the following can induce epigenetic modifications of gene expression except:

-Exercise

-Drug abuse

-Learning

-Huntington’s disease

huntington’s disease

(True/False) Potassium ions travel out of the cell through leak channels at the typical resting membrane potential of -70mV.

true

(True/False) The net drive on potassium ions at a resting membrane potential of -70mV is 0.

False

(True/False) The diffusion drive on potassium at the resting membrane potential of - 70mV is 0.

false

(True/False) At 0 mV, there is no ion flow across a typical neuron membrane because the electrochemical drive is 0.

False

The equilibrium potential of sodium (Na+) is around +55mV. Given this, which of the following is true?

check all that apply

-Opening sodium channels from rest would lead to sodium ion flow into the neuron

-Sodium ions would flow out of the neuron at +65mV

-Opening sodium channels at rest would lead to membrane depolarization

-All of the above

all of the above

What is the function of the sodium-potassium pump?

-Maintain concentration gradients across the membrane

-Keep the resting membrane potential positive

-Maintain negatively charged ions on the inside of the membrane

-All of the above

Maintain concentration gradients across the membrane

Which of the following is universally true of ion channels?

-They enable non-polar molecules to pass through the membrane

-Each is permeable to a wide variety of ions

-They are composed of unique polypeptide chains

-They do not pass ions at the resting membrane potential

they are composed of unique polypeptide chains

Cellular and Molecular Science

Focuses on the scientific study of cells, proteins, cellular systems, and the molecular basis of cell structure and function

-determines how proteins are inserted into neuron membranes

systems neuroscience

studies the dynamics of neurotransmitters. These studies cannot be done on animals so they utilize seuqnce homology

cognitive neuroscience

study of complex cognition with a focus on brain anatomy, neurotransmitters, vision, hormone or chemical changes, or cellular fluctuations in conjunction with changes in cognition

animal models

useful for accessing brain tissue and neurons through invasive experiments that cannot be done on humans

sequence homology

the shared DNA sequences for particular genes across species with a common ancestor

-looking at a particular gene thats important for learning and memory and the sequence of the gene is the same for mice as it is in humans

circuit homology

shared anatomical connectivity, cell types, and neurotransmitter systems between humans and animals

Galen

The greek physician (200 A.D) who discovered that different structures brain contributed to different bodily function

-he determined this through dissection of animals

Rene Descartes

(wrongfully) proposed that the mind and brain existed separately and the mind controlled the brain via the pineal gland

compartmentalization

the understanding that different areas of the brain control different aspects of cognitive function (motor, somatosensory cortex, prefrontal cortex)

-started with Franz Gall’s proposition of phrenology

• claimed that bumps on the cerebral cortex are associated with different personality traits, and by looking at the shape of the skull, a person’s personality and intelligence could be determined

• was proven wrong by Joseph Flourens, who empirically proved that specific parts of the brain controlled different things, and he proved this through experimental ablation

  • ablating certain parts of the brain (for example, the cerebrum) impaired certain mental and physical functions

Fritsch and Hitzig

-determined that areas of the body that require much more precise motor function occupy a larger space on the motor cortex

-discovered that stimulation on one side of the brain controlled the body movements on the contralateral side of the body in a controlled manner (mapped on the cortex)

True or False: For certain parts of the brain, it is harder to assign one particular function for that brain region

True, especially for the frontal and prefrontal cortex

What is the brain’s primary cell type?

neuron; it is about 10^-6 microns small (the soma is -50x smaller than the tip of a pencil)

What is the process of prepping a brain for microscopic viewing?

- the brain is preserved and hardened using formaldehyde

- it is then sliced very thin using a microtome

- a stain (either nissl or Golgi) is used to view the neurons in the tissue sample through a microscope

Nissl Stain

showed that a class of basic dyes could stain the nuclei of all the cells and surrounding material, called Nissl bodies

-the dye was purple and could not express the details of a neuron

reticular theory

-Proved the brain is composed of a continuous network of fused nerve processes and have two distinguishable parts; a central nucleic region called the soma, and thin neurites radiating from the soma, called axons and dendrites

-Golgi Stain allows you to see the soma, dendrites, and axons, using a yellow stain of a silver chlorate solution

Who is considered the father of modern neuroscience? Why?

Cajal because he proposed the Neural Doctrine

• states that neuronal cells are elementary functional units of the brain and communicate through contact, not continuity

• they communicate through close contacting synapses

• determined that neurons come in an incredible diversity of shapes and sizes based on their location within the brain

• different brain regions contain unique combinations of these cell types

• their morphology contributes to the way they process and transform inputs

• different brain regions are capable of performing different functions because of the morphology and diversity of cell types and their ability to compute information

• there is a relationship between morphology and physiology

dendrites

receive inputs from other neurons

axons

‘wires’ that transmit output to other neurons

soma

cell body; integrates and processes signals, then sends the signals down the axon

True or False: input equals output

False; input rarely equals output

• a dendrite can receive 1 signal from another neuron and the information can reach the soma and trigger 800 signals to be passed down the axon and be delivered to another neuron

myelin sheath

fatty substance that protects the neuron and improves the speed of electrical information through the axon

neural networks

cells are connected within a particular brain region across the brain

pyramidal neuron

-predominant neuron in the cerebral cortex

-largest neurons in the brain

- typically have dendritic spines and long bodies

stellate cell

‘star shaped’ dendrites which spread around the soma like a star

interneurons

send projections to neurons within the same brain regions

-stellate cells

projection neurons

project to other regions of the brain, different from the one that they’re in

-pyramidal neurons

dendritic spine

-exists along dendrites and contain synapses

-principal projection neurons contain these but not all neurons have them

-these are the structures that receive presynaptic input

glial cells

• make up 50-80% of cells in the brain

• support and modulate communication across neurons

• provide structural support

• regulate blood flow

• capable of signaling although not in the same way as a neuron

Transcription

• occurs in the nucleus

• DNA is transcribed into single strands of mRNA

• First, RNA polymerase binds to promoter regions of the DNA

• RNA polymerase causes the DNA strands to separate and add nucleotides to the pre-mRNA strand, which fully becomes mRNA after RNA splicing occurs

Translation

• occurs in the cytoplasm and ribosomes

• Amino acids are formed by codons, which are triplet sequences of nucleotides

• amino acids then link to form polypeptides, connected by peptide bonds

• polypeptides link and fold to form proteins

  • the way they fold and link determines their function

DNA is comprised of base pairs called

nucleotides: Adenine, Thymine, Cytosine, and Guanine

• they form base pairs which are the blueprint for the construction of proteins because they encode for amino acids

type of brain proteins

-ion channels

-structural molecules

-enzymes

-intracellular signaling molecules

-some neurotransmitters

-transport molecules

which non proteins are important in neurons

-ions

-some types of neurotransmitters

-genetic material

-vitamins/minerals

-lipids

where does translation regulation occur?

in compartments of the neuron, like dendrites and axons

-can be regulated by activity and local signaling

How does transcriptional regulation contribute to the emergence of different cell types through development?

-it starts off with genes (cells in the developing embryo all contain the same genetic material as adults) and some of the genes are transcribed into mRNA

-this process is tightly regulated during development

those genes in particular cells begin to be expressed and can encode for new transcription factors

-mRNA is translated into proteins and then those proteins ultimately determine neuron types and the neuron’s behavior and location in the brain

genome

entire set of DNA in an organism

transcriptoms

entire set of mRNA expressed in an organism

proteome

entire set of proteins in an organism; most closely related to behavior

• proteomes are the only one of three sets of mRNA that can be affected by epigenetic factors

What is the genetic codon mutation of huntington’s disease?

Abnormal CAG repeats in the huntingtin gene; results in degeneration of the basal ganglia, affecting motor and cognitive abilities

what are the ways gene expression can be affected by epigenetic structures?

drugs like cocaine upregulate many types of genes, affecting their gene expression whereas exercise can down regulate many of them

Hodgkin and Huxley

made discoveries about how electrical signals propagate axons through examining squid brains since squid have very large axons

voltage

an electrical charge across the membrane

permeability

state of a membrane that allows substances to pass through it

• Neuron membranes are semi-permeable

what do ion channels do to the membrane

they change the permeability of the membrane

• how open the ion channels are determines the permeability of the membrane

a typical neuron has a voltage of about

-70 mV; This is because the reversal potentials for Na+ and K+ represent two extremes, with the cell’s resting membrane falling somewhere in between. Since the membrane is more permeable to K+ and there is a higher concentration of K+ in the cell when the cell is at rest, the resting membrane potential is much closer to the reversal potential of K+ (-80mV ) than for Na+ (+55mV).

what causes the channel gates to open and close?

• voltage

• neurotransmitter binding

leak channels

channels that are always open to a particular type of ion

-potassium leak channels allow for the flow of potassium out of the cell in the resting potential phase

concentration gradient

when the concentration of particles is higher in one area than another

how does the diffusion drive regular K+ within the membrane

it pushes potassium out of the membrane in order to adhere to the concentration gradient

electrochemical drive

pushes positively charged potassium into the membrane to move toward the negatively charged cell

If the membrane potential becomes more positive than it is at the resting potential, the membrane is said to be

depolarized

If the membrane potential becomes more negative than it is at the resting potential, the membrane is said to be

hyperpolarized

membrane potential

the difference in the electrical charge between the inside and the outside of a neuronal membrane

How does the diffusion drive push K+ ions outside the membrane? How does the electrochemical drive work against that?

-when the membrane physiology changes, K+ leak channels on the membrane open, pushing K+ ions outside the membrane

-the force that pushes these ions outside the membrane is the diffusion drive

-electrochemistry explains that ions of the same charge repel each other, and opposite charges are attracted to one another. When the potassium leak channels open, the positively charged K+ ions flow outside, increasing the charge of the extracellular fluid

-The intracellular fluid of the membrane is now more negatively charged, attracting the positively charged K+ ions and pushing them back inside the membrane

-When the diffusion drive and the electrochemical drive completely counteract, an equilibrium is reached

net current flow

a type of flow associated with an ion

-If there is a positive current, the cell is hyperpolarizing

-If there is a negative current, the cell is depolarizing

IV curves

represents the relationship between the current flow and the voltage

-The Y axis tells the current across the membrane at different voltages along the X-axis

-The point where the current reaches zero indicated the reversal potential of the ion

sodium-potassium pump

a transport protein that uses ATP to constantly pump 3 Na+ ions out of the cell and pumps 2 K+ ions into the cell against their concentration gradient to maintain the resting membrane potential

Nernst Equation

gives the equilibrium potential for a single ion

True or False: The equilibrium potential is proportional to the ratio of concentrations inside and outside, and the polarity (+ or -) is given by the charge on the ion

true

Goldman-Hodgkin-Katz equation

-is the weighted function of the concentration of the ions weighted by their permeability

-determines the equilibrium potential for the whole membrane when the membrane is permeable to multiple ions

intracellular recordings through patchclamp electrophysiology

measuring inputs coming into the dendrites, measure the computations within the soma, and sometimes, even measure the outputs from the axon through identifying voltage changes

excitatory post synaptic potentials (EPSP)

a temporary depolarization of the post synaptic membrane caused by the flow of positively charged ions into the post synaptic cell

inhibitory post synaptic potentials

a temporary hyperpolarization of post synaptic membrane caused by the flow of negatively charged ions into the post synaptic cell

current generated post synaptic potenitals propagate through _______, to the ________

dendrites, soma

graded potentials

a small change in the membrane potential of a cell. This change in potential occurs in response to a stimulus and can be either depolarizing or hyperpolarizing

voltage gated ion channels

-they change the membrane potential, thus allowing for an action potential

-low permeability

-no flow of of preferential ion at rest

voltage gated sodium channels

-what allows Na+ to enter the cell during an action potential

-the Na+ enters the cell before K+ leaves, causing the depolarization of the cell

-when the membrane gets depolarized, voltage gated sodium channels start to open and sodium starts flowing in

-open and close in response to changes in membrane potential

action potential

sequence of voltage changes across the membrane when a signal is firing through a membrane

-all or nothing response

-the change in voltage needs to be equal to -55mV or no action potential will occur

where are action potenitals initiated?

in the axon hillock

-they are then propagated along the axon through voltage changes at the nodes of ranvier

-they pass through the axon smoothly by insulation by the myelin sheath

what do refraactory periods do?

they restrict the activation of another action potential in the same area where one just occurred

saltatory conduction

currents from the action potential leap from one hap to another in the myelin sheath

-these gaps are the nodes of ranvier

the larger the axon, the _________ they propagate

faster

How is tetrodotoxin poisoning lethal?

it blocks voltage gated Na+ channels which blocks sodium from entering the membrane

channelopathies

diseases which exist due to mutations to various types of ion channels in the brain

-can contribute to conditions such as epilepsy, which involves changes in neuronal excitability

when the action potential invades the pre-synaptic terminal,

-there is a change in the conductance of Ca2+ as a result of the activation of the voltage-gated calcium channel

-the action potential comes in, and it depolarizes the pre-synaptic terminals

-that depolarization activates the calcium voltage channels

*Ca2+ has an equilibrium potential of +137mV

-Ca2+ does not contribute much to the resting potential but it plays a huge role at axon terminals in synaptic transmission

when voltage gated Ca2+ channels open,

Ca2+ will want to rush into the presynaptic terminal

-it will depolarize the membrane potential of the presynaptic cell

summary of sequence of events in synaptic transmission

-action potential depolarizes the axon terminal

-voltage gated Ca2+ channels open

-calcium triggers neurotransmitter release

-neurotransmitter binds to receptors on the post synaptic terminal

(dendrites)

-receptors gate ion channels, causing changes in the post synaptic membrane voltage (PSPs)

How does calcium trigger neurotransmitter release?

neurotransmitter is packed into vesicles in the pre-synaptic membrane

-when the calcium enters, the vesicles will bind with the presynaptic membrane and release their contents into the synaptic cleft

quanta

-the minimum amount of neurotransmitter that can be released from the presynaptic neuron (in units of quanta)

-the amount of neurotransmitter emptied into the cleft for each of the vesicles