Neuroscience Exam #2

How did Otto Loewi show that nervous system communication must be chemical?

Through the frog experiment. He stimulated the vagus nerve and transferred the liquid from that heart to the second heart without nerves, observing as the second heart slowed down as well.

Name the 4 stages in neurotransmitter function

Synthesis & storage, release, activation, and deactivation

The presence of which ion inside the presynaptic cell is important for neurotransmitter release?

Calcium (Ca2+)

Name 2 differences in synthesis and storage of small-molecule neurotransmitters vs peptide neurotransmitters

Small-molecule NT is synthesized in the cytoplasm then loaded into vesicles, while peptide NT is synthesized in ribosomes then transported down the axon (already packaged).

What happens if acetylcholine is dumped on an acetylcholine-gated sodium channel? What if dopamine is dumped on that channel?

The channel opens when acetycholine is dumped. Nothing happens when dopamine is dumped on that channel.

Name 4 ways that a neurotransmitter’s action can be terminated.

Diffusion, Degradation, Reuptake, Glial Cell Uptake

How does the reversal potential of the ACh receptor at the neuromuscular junction show that these channels are permeable to more than one ion?

Ion channels match ion potentials.

Sodium’s reversal potential is higher than the threshold potential in most neurons. So a PSP caused by opening sodium channels is excitatory or inhibitory?

Excitatory

Potassium’s reversal potential is lower than the threshold potential in most neurons. So a PSP caused by opening potassium channels is excitatory or inhibitory?

Inhibitory

Input A into a neuron is excitatory, while Input B is inhibitory. Both are on the same dendrite but B is closer to the cell body than A. Is the neuron more or less likely to fire an action potential under the following circumstances:

a. A alone fires

b. B alone fires

c. Both A and B fire at nearly the same time

A - more likely to fire

B - less likely to fire

C - less likely to fire

What is the difference between synaptic and endocrine signaling?

Distance the signal travels, transport method, and speed of response

Is GTP typically associated with active or inactive G-proteins? What about GDP?

GTP - active

GDP - inactive

Put the following in the correct order in a typical signaling pathway:

a. cAMP generated

b. Neurotransmitter binds to metabotropic receptor

c. Adenylyl cyclase activated

d. PKA phosphorylates target

e. G-protein activated

b. Neurotransmitter binds to metabotropic receptor

e. G-protein activated

c. Adenylyl cyclase activated

a. cAMP generated

d. PKA phosphorylates target

Explain the major difference between changes in a neuron that take place in response to phosphorylation of local proteins, such as ion channels, and those that take place in response to activation of transcription factors and protein synthesis.

phosphorylation of local proteins - speed is immediate, duration of effect is short term

transcription and protein synthesis - speed is delayed, duration of effect is long term

Acetylcholinesterase breaks down acetylcholine in the synapse. Will adding acetylcholine esterase increase or decrease acetylcholine action?

Decrease.

Amphetamine blocks dopamine transporter action at the synapse. Does this drug increase or decrease dopamine’s effects?

Increases.

What neurotransmitter deficit is responsible for Parkinson’s disease? Name one way to treat it.

Caused by a deficit of the NT dopamine. One treatment option is taking levodopa (L-dopa), a dopamine precursor that crosses the blood-brain barrier.

Why do you think early drugs that treated schizophrenia caused Parkinson’s-like symptoms?

They blocked dopamine receptors.

Name 7 stages of neurotransmitter action that can be modified by psychotropic drugs.

Synthesis

Storage

Release

Receptor Activation

Inactivation

Reuptake

Autoreceptor Binding

How are nicotine and curare the same in action? How are they different?

Both have the same biological target, but they have opposite functions.

Why shouldn’t you take barbiturates and benzodiazepines at the same time?

Both medications depress your central nervous system. Taking them together amplifies sedation.

How does caffeine affect the nervous system, generally?

It increases brain and nerve activity by blocking adenosine receptors.

What is the glutamate hypothesis of schizophrenia? Why is PCP thought to induce schizophrenic-like symptoms?

glutamate hypothesis of schizophrenia - linked to under activity of NMDA

PCP is thought to induce schizophrenic-like symptoms because it blocks a specific NMDA receptor.

Name 2 effects of opioid drugs on the body.

Pupil constriction and depression of respiration

Why is Aplysia a good model system for studying learning and memory?

It has a simple nervous systems with large and easily identifiable neurons that control clearly observable behavior.

How many types of neurons are involved in habituation of the gill-siphon withdrawal reflex in Aplysia?

Two main types of neurons:

Sensory and motor

How many types of neurons are involved in sensitization of the gill-siphon withdrawal reflex in Aplysia?

Four main types of neurons:

Sensory, motor, excitatory, and inhibitory

Describe the steps / signals responsible for the neural plasticity underlying sensitization in the GSW reflex.

Step 1: neurotransmitter release

Step 2: G-Protein activation

Step 3: protein kinase A (PKA) activation

Step 4: Potassium channel closure

Step 5: action potential lengthens the duration of effect

Step 6: Enhanced calcium influx and glutamate release

What extra steps are required to induce and maintain long-term facilitation in the GSW reflex?

1. Spaced and intensified stimulation

2. Nuclear translocation and gene transcription

3. Translation

4. Synaptic structural remodeling

5. Coordinated pre- and postsynaptic signaling

How is LTP induced?

High frequency or patterned electrical stimulation of a synapse.

What is the NMDA receptor’s role in inducing LTP?

Acts as a primary gateway for calcium influx.

What is the AMPA receptor’s role in maintaining LTP?

Increasing the number and sensitivity of receptors at the postsynaptic membrane.