Brain and Behavior Unit 2

Action potentials, neural communication, neurotransmitters.

Why do neurons need Na+/K+ pumps?

Why do neurons need Na+/K+ pumps?

Neurons needs these pumps to restore resting potential.

EPSP

Excitatory Postsynaptic Potentials. Encourages the neuron to fire an action potential.

IPSP

Inhibitory Postsynaptic Potentials. Discourages the neuron from firing an action potential.

Why are reuptake and enzymes important?

They shut off neurotransmitter signals.

Where would ligand-gated ion channels be found?

Ligand-gated ion channels are found on the dendrites.

Relative Refractory Period

When a neuron could fire an action potential (after already firing an AP) if it receives a large amount of stimulation.

Absolute Refractory Period

When a neuron can no longer fire an action potential (after firing an AP) no matter how much stimulation is given, until it returns to it’s resting potential.

What does the “all-or-nothing“ law apply to?

Action potentials.

Where does the action potential start?

Axon Hillock.

In myelinated neurons, where the the action potential regenerate?

Nodes of Ranvier.

What is another term for “neural integration?”

Summation

Why is diffusion and electrostatic pressure important?

They are important for moving ions across the neuronal membrane.

Electrostatic pressure

Opposite charges attract, like charges repel.

Where are degrading enzymes found?

The synapse.

Exocytosis

The releasing of a neurotransmitter.

Where are reuptake transporters found?

The presynaptic membrane.

Action potential

The electrical signal that travels within a single neuron along it’s axon.

Where does neural integration (or summation) happen?

The soma (cell body)

Vesicles

Where neurotransmitters are stored before they are released.

Threshold of Excitation

The minimum amount of net excitation needed to fire an action potential.

Why is neural integration important?

To determine if the threshold of excitation has been reached.

Why is reuptake important?

It is important because it allows the neurotransmitter to be ‘recycled.‘

Does the effects of a psychoactive drug last longer if it gets to the brain quickly?

No, the effects of a psychoactive drug do not last longer.

Acetylcholine (AcH)

This neurotransmitter is found in many areas of the peripheral nervous system. This includes the muscular junction and throughout the PNS (parasympathetic nervous system.)

Tolerance

When the body is attempting to maintain homeostasis, the person will need to take more of a drug in order to feel the same effects. There will be changes to the brain cells and increase in liver enzymes.

Norepinephrine

Associated with wakefulness, arousal, vigilance, and energy.

Which pathway is important for reward? (including drug reward.)

The mesolimbic pathway.

Is “snorting“ a drug the same as inhalation?

No, inhalation is different.

Dopamine

This neurotransmitter is associated with feelings of pleasure, satisfaction, and motivation. It has several different effects for the following pathways:

Mesotriatal: Movement

Mesocortical: Cognition

Mesolimbic: Reward

Naloxone (Narcan)

An endorphin receptor antagonist that can (temporarily) counteract an opioid overdose.

Serotonin

Associated with happiness, focus, and calmness, this neurotransmitter can be found in the Ralphei nuclei in the brainstem.

What is happening to a person who has Parkinson’s disease?

Their mesotriatal pathway is degenerating.

L-DOPA

Parkinson’s patients take this drug in order increase dopamine levels.

What is another term for the mesotriatal pathway?

The nigrostriatal pathway.

GABA (Gamma-aminobutryic Acid)

This inhibitory neurotransmitter is primarily found in the Central Nervous System. As the name implies, it is also an amino acid.

What neurotransmitters are also amino acids?

GABA and Glutamate.

Endorphin

Derived from the term ‘endogenous morphine,‘ this peptide neurotransmitter is a natural pain reliever that binds to mu receptors.

Retrograde Messaging

This can also be seen as a message going ‘in reverse.‘ This is when the signaling comes from the post-synaptic cell back to the presynaptic to either stop or take action. A neurotransmitter that does this is anandamide.

Mechanism of Action

Describes how a drug or other substance produces an effect on the body. This includes:

-Neurotransmitter Production

-Neurotransmitter Storage

-NT release

-NT Binding

-Reuptake

-Enzyme Degradation

Agonist

Increases neurotransmitter activity (typically only effects one or two types of NTs)

Antagonist

Decreases neurotransmitter activity (typically only effects one or two types of NTs)

Placebo Effect

A positive or negative response to a ‘fake‘ treatment. Ex. Patients reporting that their depression symptoms lessened after taking a sugar pill when they thought it was an anti-depressant.

Homeostatic Mechanism

The body adjusting itself physiologically to tolerate continous imbalancing.

Metabolic Tolerance

The body becomes more efficient at metabolizing substances. Ex. Drugs or alcohol.

Functional Tolerance

Brain cells will adapt to continuous disruptions by increasing or decreasing NT production/receptors. This is highly dependent on genetics. (Also called “cellular tolerance“)

Withdrawal

When the body adapts to a certain substance - when it goes without, the body will experience adverse symptoms. This is usually opposite of what the substance was providing.

Psychoactive Drugs

These types of drugs impact synaptic transmission.

SSRIs (Selective Serotonin Reuptake Inhibitors)

This class of antidepressants are serotonin agonists. They block reuptake, allowing it to stay in the system for longer periods of time.

ex. Zoloft, Prozac, etc.

MAOIs (Monomine Oxidase Inhibitors)

This class of antidepressant are agonists. They block degrading enzymes. This is an older class of drugs that are not typically prescribed for their numerous side effects.

Saltatory Conduction

How an electrical impulse skips from node to node along an axon.

Depolarization

Also called the “rising phase,” this is caused when Na+ rushes into the neuron.

Hyperpolarization

This is when the neuron goes through a phase of becoming more negative. It helps in preventing more stimulation from occuring.

Repolarization

Potassium begins to leave the cell through potassium pumps. This phase helps restore the charges across the concentration gradient.

Black Widow Venom

An agonist, makes the body release acetylcholine at the neuromuscular junction. Causes the body to spasm.

Botulinum Toxin

An antagonist, blocks acetlycholine release in a localized area. Causes the muscle to be paralyzed.

1st Generation Antipsychotics

Blocks dopamine receptors. They treated positive, but not negative, symptoms for schizophrenia. They have movement related side-effects, such as tardive dyskinsea. Not typically prescribed.

2nd Generation Antipsychotics

Primarily blocks serotonin (and some dopamine) receptors. Treats positive and negative symptoms in schizophrenia, with less risk of movement related side effects. There are metabolic side effects.

What do most antipsychotics have in common?

They are all typically antagonists.

Tryciclic Antidepressants

Blocks serotonin and norepinephrine reuptake. They are less likely to be used.

Serotonin Norepinephrine Reuptake Inhibitors (SNRIs)

Prescribed for depression and anxiety, they block reuptake for 5-HT and NE receptors.

What do most antidepressants have in common?

They are typically all agonists and treat depression/anxiety.

How does sex effect a person’s response to drugs?

• Women are typically more sensitive to drugs than men are

• There can be sex differences in levels of enzymes that process drugs.

Where do psychedelic drugs produce their effects?

• 5 HT-2A Receptors

• The area of the brain associated with REM sleep

• areas of the brain associated with cognition and perception.

What does breast milk do for the infant brain?

It helps promote myelination in the infant brain.

What substanced supresses the medulla’s respiratory center?

-Alcohol

-Barbituates

-Opioids

What theory of addiction does the DARE program use?

The moral model.

What is serotonin derived from?

The essential amino acid, tryptophan.

What is dopamine derived from?

The amino acid, tyrosine.

What is norepinephrine derived from?

It is made from the neurotransmitter, dopamine.

5-HT 2A Receptor

This subtype of serotonin receptors is involved with learning, memory, and neurogenesis. Agonists for this receptor tend to be hallucinogenic in nature, and produces “mystical states.“

Common Agonists: LSD, Psilocybin

What are some amino acid NT?

• GABA

• Glutamate

• Acetylcholine

• Norepinephrine

• Dopamine

• Serotonin

Glutamate

A common excitatory neurotransmitter.

Dopaminergic

Referring to cells that use dopamine as their synbaptic transmitter.

Serotonergic

Referring to cells that use serotonin as their synaptic transmitter.

Noradrenergic

Referring to cells using norepinephrine as their synaptic transmitter.

Locus coeruleus

A small nucleus in the brainstem whose neurons produce NE and modulate large areas of the forebrain.

Lateral tegmental area

A brainstem region that provides some of the NE-containing projections of the brain.

Ventral Tegmental Area (VTA)

A portion of the midbrain that projects dopaminergic fibers to the nucleus accumbens.

Ligand

A substance that binds to receptor molecules as a neurotransmitter or drug that binds postsynaptic receptors.

Down-Regulation

A compensatory decrease in receptor availability at the synapses of a neuron

Up-Regulation

A compensatory increase in receptor availability at the synapses of a neuron.

Anxiolytic

A drug that is used to combat anxiety.

Analgesic

Having painkilling properties.

What three main presynaptic actions to psychoactive drugs have?

Alter transmitter synthesis, alter NT release, block the transmitter

Mesolimbic Pathway

This pathway is responsible for transporting dopamine from the VTA to the nucleus accumbens and amygdala.

Mesostriatal Pathway

This pathway is a dopaminergic pathway, and is involved with motor planning. Many first generation antipsychotics interfered with this pathway, resulting in tardive dyskinesia and Parkinsonian movements.