NEURO- quiz 4-15

In the visual system, the ON and OFF center bipolar cells have different responses to activation of the photoreceptor cell because

They have different receptors that either excite or inhibit the bipolar cell in response to the neurotransmitter released by the photoreceptor cells

In the 1990s, drug users started developing Parkinson's like symptoms. It was found that a contaminant, called MPTP, was in an opioid-like drug. MPTP was converted to MPP+. How does MPP+ cause Parkinson's like symptoms?

MPP+ inhibits mitochondrial function in dopaminergic neurons.

Rett syndrome is caused by mutation in gene called MeCP2. Why does mutation of this one gene cause so many neurological defects?

MeCP2 binds to methylated DNA and regulates gene expression.

The developmental disorder fragile X syndrome is caused by a mutation that prevents the expression of the FMRP protein. A decrease in the number of receptors for which neurotransmitter might be expected to compensate for the lack of FMRP?

glutamate

Parkinson's disease leads to the death of dopaminergic neurons in the SNc. This, in turn leads to

increased inhibition of neurons in the brainstem that regulate motor function

More genes affecting cognitive function have been mapped to the X chromosome than other chromosomes because

mutations on the X chromosome are more easily studied because males only have one copy

Autism spectrum disorders covers a large number of disorders. What do they share in common?

problems with communication and social interactions

When you stimulate a presynaptic neuron, you see hyperpolarization of the postsynaptic neuron. This suggests that the presynaptic neuron releases

Answers: ATP glutamate **GABA** acetylcholine dopamine

What is the receptive field of a visual neuron?

Answers: All of the synaptic connections to a retinal neuron **The part of the visual field that influences that neuron's activity**

Your colleague Prof Peacock is examining the escape circuit in the crayfish by recording from isolated neurons. The circuit consists of a sensory neuron that senses touch connected to a motor neuron that produces an escape behavior. He finds that reducing the Na+ concentration in the solution surrounding the neurons causes a reduction in the escape behavior when the sensory neuron is stimulated. However, a reduction in the Ca2+ concentration does not affect the escape behavior when the sensory neuron is stimulated. What is the most likely explanation for Prof Peacock's results?

Answers: Ca2+ is not necessary for the formation of an action potential **The neurons are connected by an electrical synapse** The presynaptic vesicles can use the "kiss and run" mechanism There is a mutation in the SNARE proteins allowing them to cause fusion in response to Na+ There is no way for neural transmission to work without Ca2+, so clearly Prof Peacock has contaminated all of his solutions with calcium

Which of these is true about cannabinoid signaling? Choose all that apply.

Answers: Cannabinoids are packaged in the Golgi It does not require receptors **It does not require vesicles** **Cannabinoids are made in the postsynaptic neuron** Cannabinoids are made in the presynaptic neuron

Which of these structures is not involved in recycling of vesicles?

Answers: Coat proteins (like clathrin) Cisterna Endosomes **Microtubules**

What type of visual information is coded in the retina? Choose all correct answers.

Answers: Distance **Direction of movement Edges **Contrast

The nicotinic acetylcholine receptor is an example of a _______ receptor, and the muscarinic acetylcholine receptor is an example of a _______ receptor.

Answers: G protein coupled, metabotropic ligand gated, voltage gated potassium, calcium ***ionotropic, metabotropic*** metabotropic, ionotropic

Reserpine is used to treat schizophrenia and it acts by blocking vesicular monoamine transporters (VMATs). Which neurotransmitter systems are influenced by reserpine? Select all that apply.

Answers: GABA ***Dopamine ***Serotonin Glutamate Acetylcholine ***Norepinephrine

There is a glycine gated Cl- channel on the post synaptic neuron. When glycine is released from the presynaptic neuron, what will happen in the post synaptic neuron?

Answers: It will be depolarized Voltage gated Na+ channels will open A G protein will be activated Ca2+ will enter the cell **It will be hyperpolarized**

An agonist is a molecule that

Answers: Leads to release of neurotransmitter **Activates a receptor** Inactivates a receptor Reduces the charge on the membrane Prevents the release of neurotransmitter

What mechanism is used to put neuropeptides into vesicles?

Answers: Microtubules Endocytosis **The Golgi** A channel protein A transporter protein

The main excitatory neurotransmitter in the mammalian central nervous system is

Answers: Serotonin (5HT) Acetylcholine Dopamine **Glutamate** GABA

What is quantal release of neurotransmitter?

Answers: The amount of neurotransmitter released in response to one action potential Release of one neurotransmitter molecule at a time Release of the neurotransmitter in all of the docked vesicles at the same time Release of transmitter from areas in the cell besides the synapse **Release of neurotransmitter in discrete units corresponding to vesicle fusion**

The term EPSP refers to

Answers: The arrival of the action potential in the presynaptic neuron A current into the postsynaptic cell **A depolarization of the membrane of the postsynaptic cell** A hyperpolarization of the postsynaptic cell A more positive membrane potential in the presynaptic neuron

If midget ganglion cells in the retina were specifically destroyed, what would happen to vision?

Answers: The person would lose the ability to discriminate red and green.

Which of these is true about vesicles using the "kiss and run" process?

Answers: They are from the reserve pool **They do not become part of the plasma membrane** They are not recycled They do not release neurotransmitter They use coat proteins (such as clathrin) during recycling

What is the role of SNARE proteins in the release of neurotransmitter? (Choose all that apply.)

Answers: They bind to motor proteins that transport the vesicles to the axon terminus They provide energy to fill the vesicle with neurotransmitter -They provide the energy for the fusion of the vesicle membrane with the cell membrane** -They bring the vesicle close to the membrane in the "docked" position** They help form the vesicle from the cell membrane during vesicle recycling

Which of these is not true about the receptive fields of simple cells in the visual cortex (V1)?

Answers: They have an ON and an OFF region **They have very large receptive fields

What is the function of a kinase?

Answers: To activate Ca2+ channels To convert ATP to cAMP To breakdown cAMP to AMP To remove the phosphate from proteins reducing their activity **To phosphorylate proteins altering their activity**

Which of these is/are evidence that schizophrenia involves neurotransmitters other than dopamine? (Choose all that apply.)

Answers: Treatment with inhibitors of the serotonin reuptake transporter treats the negative symptoms of schizophrenia ***Drugs that act at NMDA receptors induce schizophrenia like symptoms ***Dopamine receptor antagonists treat only positive symptoms of schizophrenia ***About 30% of people with schizophrenia do not respond to treatment with dopamine receptor antagonists Drugs that affect mitochondrial function induce schizophrenia like symptoms

A dopaminergic neuron is one that

Answers: responds to dopamine **synthesizes and releases dopamine**

Familial Alzheimer's disease is associated with mutations in which proteins? (Choose all that apply.)

Answers: tau synuclein **γ-secretase pink **APP

Acetylcholine acts at a GPCR on heart muscle to make the heart beat more slowly. The βγ subunits of the G protein bind to K+ channels in the plasma membrane causing them to open. Which of the following conditions would decrease the effect of acetylcholine? (Choose all that apply.)

Answers:(all answer choices) -mutations in the K+ channel that keep it closed all the time addition of a drug that prevents the GTP bound to the Gα subunit from being converted to GDP -adding acetylcholinesterase to the external environment of the cell -a mutation that decreases the binding of the βγ complex of the G protein to the K+ channel -a mutation in the acetylcholine receptor that prevents its localization on the cell surface

Which of these structures is/are involved in direct transmission? (Choose all that apply)

Answers: -Electrical synapses** G proteins -Ionotropic receptors** Metabotropic receptors -Neurotransmitters**

Activating the Gq signaling pathway leads to (choose all that apply)

Answers: -Formation of IP3** Activation of protein kinase A (PKA) Increases in intracellular cAMP -Activation of phospholipase C** -Increases in intracellular Ca2+**

Most current anti-depressants are SSRIs. What is the result of SSRI action?

Increase in amount of serotonin in the synaptic cleft through the inhibition of the uptake transporter

Which one of these would be a drug with the most specific mechanism of action?

A D2 dopamine receptor antagonist

The reversal potential of a channel is the membrane potential at which

Answers: A different ion flows through the channel Negative rather than positive ions flow through the channel The channel closes preventing ions from flowing across the membrane **There is no net flow of ions through the channel** The channel opens allowing ions to flow across the membrane

An important step in trying to treat neurodegenerative diseases is to find "biomarkers" for the disease. What is a biomarker?

An identifiable biological change that happens before symptoms appear

Put the following events in the correct order.

Answers 1. An action potential is generated in the axon 2. Depolarization of the presynaptic terminal 3. Opening of voltage gated Ca2+ channels 4. Ca2+ entry into the presynaptic terminal 5. Fusion of synaptic vesicle with the presynaptic plasma membrane 6. Neurotransmitter release

Which of these are considered to be second messengers? (Choose all that apply.)

Answers: ***Ca2+ Protein kinase C (PKC) ***cAMP Adenylyl cyclase Na+

The enzyme adenylyl cyclase

Answers: **Converts ATP to cAMP** Activates Ca2+ channels Activates G proteins Breaks down cAMP Phosphorylates proteins

The highly addictive drugs amphetamine and cocaine work by

Answers: **Decreasing the activity of reuptake transporters** Acting as agonists at dopamine receptors Increasing the activity reuptake transporters Inhibiting monoamine oxidase Inhibiting the enzyme that synthesizes dopamine

Which of these neurotransmitters regulates an ion channel receptor?

Answers: **Glycine** Cannabinoids Dopamine An opioid Norepinephrine

What is the function of IP3?

Answers: **It releases Ca2+ from the endoplasmic reticulum** It activates protein kinase A (PKA) It activates protein kinase C (PKC) It causes Ca2+ channels to open It activates phospholipase C

Which of these is true about neurotransmitter gated ion channels?

Answers: **None of the statements are true** The neurotransmitter diffuses through the channel to activate the receptor They use energy from ATP to move ions against the electrochemical gradient They only allow ions to flow in one direction One type of ion channel will allow both K+ and Cl- to flow through since these ions have similar equilibrium potentials

Which of the following happens when a G-protein-coupled receptor activates a G protein?

Answers: **The α subunit releases its bound GDP and binds a new molecule of GTP.** The β subunit releases its bound GDP and binds a new molecule of GTP. The GDP bound to the α subunit is phosphorylated by a kinase to form bound GTP. The G-protein-coupled receptor phosphorylates the GDP bound to the α subunit. The G-protein-coupled receptor activates the α subunit and inactivates the βγ complex.

Which of these is true about horizontal cells (choose all that apply)?

Answers: **They make synapses with multiple cone cells Their axons make synapses with bipolar cells **They are inhibitory **They are involved in color vision They generate action potentials

What mechanisms are used to clear neurotransmitters from the synaptic cleft? Select all that apply.

Answers: -Diffusion** Endocytosis -Degradation by enzymes** -Reuptake by transporters** Binding to receptors

How is the function of the Rho protein normally regulated?

Binding GTP activates it, and the conversion of GTP to GDP inactivates it

Fura2 can be used to investigate signaling by calcium because it

Binds to the cell membrane reducing the permeability of cells for calcium **Changes its excitation spectrum in the presence of calcium** Blocks calcium channels Blocks gap junctions preventing the formation of calcium waves Chelates calcium removing it from the extracellular solution

Induced pluripotent stem cells are

Cells that are forced to differentiate into different cell types by causing changes in the expression of specific transcription factors

Fragile X syndrome is due to a loss of the FMRP protein. What is FMRP's normal function?

It binds to specific mRNAs decreasing translation

A mouse model of Rhett syndrome was generated in which the Mecp2 gene was knocked out. The abnormal phenotype of this mouse could be rescued by expression of MeCP2 in young mice, even if they had not expressed MeCP2 during development. Why is this an important finding?

It indicates that the symptoms are reversible and therefore the disease can be treated by restoring MeCP2.

One protein implicated in intellectual disability (ID) is oligophrenin. How does this protein influence neurons?

It is a GAP protein that regulates Rho signaling, which effects dendritic spine length

What is the normal function of the Tau protein?

It is a microtubule accessory protein that regulates interactions between filaments.

Potentiation refers to

Selected Answer: An increase in the excitatory postsynaptic potential

Which of the following statements best reflects the nature of synaptic plasticity?

Selected Answer: Synaptic response changes in magnitude depending on frequency of stimulation.

Why are action potentials usually generated at the axon hillock in vertebrate neurons?

Selected Answer: There is a high concentration of voltage gated Na+ channels at the hillock.

Name one mechanism that takes place in the presynaptic neuron that would lead to facilitation.

Selected Answer: To change facilitation, one of the things would be how much neurotransmitters are realeased. (only got 1/2 a credit)

Autoinhibition occurs when

Selected Answer: an inhibitory receptor that responds to the neurotransmitter being released is located on the presynaptic neuron

What is the main pathological feature of prion diseases?

Spongiform encephalitis