Psych 301 Unit 2

What kind of organization does point to point communication employ?

Presynaptic neuron sends signals down axon and out synapse to dendrites of the postsynaptic neuron.

What kind of organization does diffuse modulatory employ?

Presynaptic neuron sends signal down axon that branches and projects wildly throughout the brain, to many different parts of the brain.

What is the function of point to point communication?

It is essential in informational processing, and it turns sensory signals into physical motor output.

What is the function of modulatory diffuse systems?

They control neural processing, taking sensory input and in turning it into chemical release or inhibition in the brain (based on mood, arousal, etc).

What are the most common neurotransmitters in point to point communication?

glutamate (excitatory) and GABA (inhibitory)

What are the most common neurotransmitters in diffuse modulatory systems?

serotonin, dopamine, and norepinephrine

During a seizure, the signaling in which 2 neurotransmitters are imbalanced?

excitatory and inhibitory neurotransmitters

Sensory neurons perform what?

transduction

What is transduction?

Turning physical signals in the world into electrical activity in the neurons

Photoreceptors turn — into —?

light, electrical activity

Photoreceptors are used for transduction in which sensory system?

the visual system

Mechanoreceptors convert — into —?

physical movement, opening and closure of ion channels

Mechanoreceptors are used for transduction in which sensory systems?

the auditory and somatosensory systems

Motor neurons do what?

synapse onto muscle fibres

What is the neurotransmitter used at the neuromuscular junction?

acetylcholine

What causes contraction in a muscle fiber?

an excitatory postsynaptic potential

What is the benefit of ionotropic over metabotropic receptors in motor neurons?

Ionotropic receptors produce much faster signals than metabotropic receptors do, which is needed in cases of involuntary reflexes and quick response times to stimuli.

Where are norepinephrine cell bodies located?

in the locus coeruleus

What is the main function of norepinephrine?

increasing arousal and attention

How, in norepinephrine, does increased arousal and attention result?

Via a mechanism that facilitates neural signaling, making neural signaling more efficient.

What is the mechanism that norepinephrine uses to make neural signaling more efficient?

Norepinephrine activates a metabotropic receptor on a postsynaptic neuron that encourages K+ channels to close, which decreases the likelihood that positive ions leak out of the cell. The makes the cell able to hold onto depolarization better, making them more excitable.

Where are serotonin cell bodies located?

in Raphe nuclei

What is one main function of serotonin?

Decreasing arousal/regulating mood.

Where are dopamine cell bodies in the nigrostriatal pathway?

in the substantia nigra

Where does dopamine project to in the nigrostriatal pathway?

to the basal ganglia

What is the main function of dopamine in the nigrostriatal pathway?

regulation/initiation of voluntary movements

In what pathway of dopamine is impacted in diseases like Parkinson’s and Huntington’s?

the nigrostriatal pathway

Where are dopamine cell bodies in the mesolimbic pathway?

in the ventral tegmental area

Where do dopamine cell bodies project to in the mesolimbic pathway?

the limbic system, the nucleus accumbens, and the frontal cortex

What are the main functions of dopamine in the mesolimbic pathway?

reward prediction, reinforcement value of behaviors, learning and addiction

What is pharmacokinetics?

How does the body act on a drug?

What is pharmacodynamics?

How does the drug act on the body?

What is homeostasis?

A self regulating process by which a living organism can maintain internal stability while adjusting to changing external conditions.

What is a ligand?

Is any molecule that interacts with a given receptor.

What is a neurotransmitter?

A molecule that’s primary role is carrying chemical signals from one cell to the next.

What does it mean for something to be endogenous?

It means that it originated inside the body.

What does it mean for something to be exogenous?

It originated outside of the body.

What is absorption in terms of drugs?

The process of a drug entering the bloodstream.

What does distribution mean in terms of drugs?

The dissemination of a drug throughout the body’s organs and tissues.

What does metabolism mean in terms of drugs?

The irreversible transformation of a drug into metabolites.

What are metabolites in terms of drugs?

Smaller metabolized version of the drug, that may have a higher chance of being able to cross the blood brain barrier.

What is excretion in terms of drugs?

The removal of the drug and metabolites from the body.

What is the half life of a drug?

The time required to remove half of the maximum concentration of the drug from the blood.

Which methods of administration of drugs have a shorter half life and faster rise of concentration in the blood?

Smoking and intravenous (injection) methods have the shortest half life and the fastest rise of concentration in the blood.

What’s the relationship between the half life/rise of concentration in the blood and the Cmax of a drug?

The higher the Cmax of a drug the quicker it is going to reach that max and the quicker it is going to reach its half life.

What are the main 3 mechanisms of action of drugs?

Agonists, antagonists, and reuptake inhibitors.

Benzodiazepines are agonists of ________ recepetors

GABA

Morphine and heroin are agonists of __________ receptors.

Dopamine

Curare (ancient arrow tip poison) is the antagonist of _________ receptors.

Acetylcholine

Why could curare poisoning lead to death?

Acetylcholine is the main neurotransmitter in involved in muscle movement, and the reduction of it to cells could cause paralysis.

What does a drug do if it is considered an agonist?

It enhances/facilitates signaling of a neurotransmitter at that specific synapse.

What does a drug do if it is considered an antagonist?

It suppresses/reduces signaling of a neurotransmitter at that specific synapse.

What does a drug do if it is considered a reuptake inhibitor?

It blocks proteins on the presynaptic terminal that are removing neurotransmitters from the synaptic cleft. They increase signaling of a neurotransmitter because more of the neurotransmitter is left in the synaptic cleft to bind to receptor on the postsynaptic cell.

Fluoxetine is a reuptake inhibitor for what neurotransmitter?

serotonin

What are SSRIs?

Selective serotonin reuptake inhibitors, often used to treat depression.

Cocaine is what kind of drug?

A reuptake inhibitor.

Would the endogenous opioid system be better classified as point to point communication or as a diffuse modulatory system?

A diffuse modulatory system.

What are the different variants of opioid receptors associated with different functions/effects?

Morphine and heroin are _______ of opioid receptors and induce a _______ postsynaptic response than endogenous opioids do.

What factors influence the effect of a given drug?

The method of administration and the distribution throughout the body

What is addiction?

The preoccupation with obtaining a drug, compulsive use of the drug in spite of adverse consequences.

What is withdrawal?

The negative reaction that occurs when drug use is stopped.

What is addiction NOT?

Fueled by a user’s desire to avoid withdrawal symptoms or the pleasurable effect of the drug

What are typical characteristics of withdrawal symptoms?

Typically withdrawal symptoms swing in the opposite direction and produce affects that are opposite of what the drug does.

What brain area is associated with addiction?

the VTA (ventral tectal area)

What brain area is associated with withdrawal?

the PAG (periaqueductal gray)

What was the task in the Bozarth and Wise studies?

The task was for rats to press a lever to inject morphine into either their VTA or PAG areas of the brain.

What were the experimental designs for the Bozarth and Wise studies?

Rats were to press a lever to inject morphine into either their VTA or PAG, and after chronic injection were attempted to induce withdrawal by injecting naloxone into that same area.

What were the main observations in the Bozarth and Wise study?

Rats who had morphine injected into their VTA became addicted, but injecting naloxone into that same area did not induce withdrawal. Rats that had morphine injected into their PAG did not become addicted, but withdrawal symptoms did occur when naloxone was injected into that same area. Suggested that the VTA was involved in addiction but not withdrawal and the PAG was involved in withdrawal but not addiction.

What did the Wise 2004 study provide that supported the idea that the DA system was necessary for the expression of addictive behavior?

Rats quickly learned that if they press a lever, a small drug pellet will be dispensed, and soon are pressing the lever incessantly.

Does the Wise 2004 study provide causal or correlational evidence?

Causal evidence

What kind of drug is cocaine?

a reuptake inhibitor of dopamine

What kind of drugs are methamphetamines?

agonists of dopamine

What is the method of action of methamphetamines?

It mimics dopamine and enters vesicles in the presynaptic neuron pushing dopamine out

What kind of drug is LSD?

can be an agonist and antagonist of serotonin

What is the method of action of LSD?

it mimics serotonin and binds to its receptors

What kind of drug is ecstasy?

an agonist of serotonin

What is the method of action of ecstasy?

it mimics serotonin and is take up by serotonin transporters. It confuses the transporters and subsequently serotonin out into the synaptic cleft

What kind of drug is alcohol?

an agonist of GABA and an antagonist of glutamate

What kind of drug is heroin?

an agonist of dopamine

What is the mechanism of action of heroin?

It mimics the body’s natural opiates and binds to opioid receptors turning off dopamine inhibition

Neurons in the VTA project to the _________, releasing _________ onto neurons in that region.

nucleus accumbens, dopamine

Would you predict the rats from the Wise 2004 study would show symptoms of withdrawal?

yes, they are ingesting and metabolizing the drug

Virtually all abused drugs, and rewarding behaviors, increase dopamine levels in the -

nucleus accumbens

In the monkey/light/juice study, what does the activity of DA neurons look like before learning/when reward comes as a surprise?

The monkey is given juice (the reward), DA neurons in the VTA fire and release dopamine

In the monkey/light/juice study, what does the activity of DA neurons look like after learning?

When the light begins to turn on before the monkey is given juice, DA activity shifts from the time of the reward to stimulus that predicts reward (the light)

In the monkey/light/juice/study, what does the activity of DA neurons look like when a reward is expected but not received?

When the light turns on and no reward is given, DA neurons are briefly suppressed

The DA activity in the monkey/light/juice study is not technically represented by the reward but rather what instead?

the DA activity represents the expected value of the reward

Many drugs’ mechanisms of action is what?

Directly interacting with dopaminergic neurons of the VTA, modulating the amount of DA released outside of the natural range

Drugs that act directly on neurons in the VTA, -

the DA responses are not tapered over time, like they are endogenous stimuli (are consistent)

Compared to the monkey/light/juice experiment, how and when is the pattern of DA activity evoked by drugs different?

DA activity caused by drugs is consistent and DA activity caused by external stimuli are inconsistent

Most researchers agree that _______ is an essential fact in _____ drug taking.

DA mediated reinforcement, early

But researchers believe that _______ underlies _______ drug addiction.

neural plasticity, long term

What’s the main lesson from the study that looked at relapse in Vietnam vets?

DA systems change in long term drug users, fewer DA receptors

What is conditioned tolerance?

a higher dose of a drug can be tolerated when external stimuli associated with prior administration of the drug are present. if such stimuli are absent, administration can lead to an overdose

What study showed conditioned tolerance?

Siegel et al 1982, more rats overdosed in an environment unfamiliar with their normal injection site

Declarative/explicit memory is -

easier to form, but more easily forgotten

Semantic memory is?

facts

Episodic memory is?

events

Where in the brain deals with declarative memory?

the Medial Temporal Lobe (next to the hippocampus)