Lecture #8 Study Guide

Why are synapses important for behavior?

Synaptic activity helps control behavior, so changing how synapses work can change behavior.

What can happen when a disease disrupts synaptic function?

It can cause major changes in nervous-system function and behavior.

What is myasthenia gravis?

An autoimmune disorder in which the immune system attacks postsynaptic acetylcholine (ACh) receptors.

What does ACh stand for?

Acetylcholine.

What is the neuromuscular junction?

The connection between the nervous system and muscles.

At the neuromuscular junction, which cell releases acetylcholine?

The presynaptic neuron.

At the neuromuscular junction, what is the postsynaptic cell?

The muscle cell.

What normally happens when acetylcholine binds to receptors on a muscle?

The muscle contracts.

Why does myasthenia gravis cause muscle weakness?

Acetylcholine receptors are lost, so muscles receive less of the signal telling them to contract.

Why can severe myasthenia gravis interfere with breathing?

The diaphragm can become too weak to work properly.

What may someone with severe myasthenia gravis eventually need?

A ventilator.

According to the lecture, is there currently a cure for myasthenia gravis?

No.

What type of neurons are primarily lost in Parkinson's disease?

Dopaminergic neurons, meaning neurons that use dopamine.

What does DA stand for?

Dopamine.

Where are the dopamine neurons lost in Parkinson's disease primarily located?

The substantia nigra.

What does "substantia nigra" refer to in the lecture?

A brain area containing dopamine neurons that have dark pigment.

What happens to substantia nigra neurons as Parkinson's progresses?

They progressively die.

What larger brain system includes the substantia nigra?

The basal ganglia.

What major function is associated with the basal ganglia?

Movement.

Why is Parkinson's considered a movement disorder?

Loss of dopamine neurons in the basal ganglia makes voluntary movement difficult.

What characteristic walking pattern can occur in Parkinson's disease?

A shuffling gait.

What is a tremor?

Shaking.

What type of tremor is characteristic of Parkinson's disease?

A resting tremor.

What is a resting tremor?

Shaking that occurs while the person is at rest rather than intentionally moving.

Is an intention tremor the characteristic Parkinson's tremor?

No. Parkinson's is associated with a resting tremor.

Does having a tremor automatically mean someone has Parkinson's disease?

No.

Why can't Parkinson's disease simply be treated by giving dopamine?

Dopamine cannot cross the blood-brain barrier.

What cells help form the blood-brain barrier according to the lecture?

Astrocytes.

What happens to dopamine given from outside the brain?

It stays in the peripheral nervous system instead of crossing into the brain.

What dopamine precursor is used for Parkinson's disease?

L-DOPA.

Why can L-DOPA be used when dopamine itself cannot?

L-DOPA can cross the blood-brain barrier.

What does the body do with L-DOPA after it enters the brain?

It uses L-DOPA to make dopamine.

Why doesn't L-DOPA cure Parkinson's disease?

The dopamine-producing neurons continue to die.

What can happen with continued L-DOPA treatment?

Tolerance can develop, so more L-DOPA may be needed for the same effect.

What can happen as the L-DOPA dose is increased?

Side effects can also increase.

According to the lecture, is there currently a cure for Parkinson's disease?

No.

How is Huntington's disease movement different from Parkinson's disease?

Parkinson's involves difficulty moving, while Huntington's involves too much uncontrolled movement.

What does HD stand for?

Huntington's disease.

What does PD stand for?

Parkinson's disease.

What is chorea?

Uncontrollable, dance-like movements.

How can chorea progress in Huntington's disease?

It can begin with movements of the arms or head and progress until everyday activities become difficult.

What problems may occur before obvious movement symptoms of Huntington's disease?

Depressive symptoms and cognitive decline.

Is Huntington's disease genetic?

Yes, it is a strongly genetic disorder.

What type of inheritance does Huntington's disease have?

Autosomal dominant.

What does autosomal dominant mean for Huntington's disease?

Having the mutant version of the gene causes the disorder.

If a parent has Huntington's disease, what chance does the lecture give of passing the gene to an offspring?

50%.

Why is the typical timing of Huntington's symptoms especially problematic?

Symptoms often begin in midlife, after people may have already had children.

According to the lecture, is there currently a cure for Huntington's disease?

No.

What part of the basal ganglia is damaged in Huntington's disease?

The caudate-putamen, collectively called the striatum.

What specific neurons die in the striatum in Huntington's disease?

Medium spiny neurons.

Are medium spiny neurons excitatory or inhibitory?

Inhibitory.

What neurotransmitter do the medium spiny neurons discussed in Huntington's disease use?

GABA.

What happens to inhibitory input when medium spiny neurons die in Huntington's disease?

The next cells receive less GABA inhibition.

Why does loss of GABA inhibition contribute to uncontrolled movements in Huntington's disease?

The normal "braking" or inhibition of movement is lost.

According to the lecture's comparison, what neurotransmitter input is lost in Parkinson's disease?

Dopamine input.

According to the lecture's comparison, what neurotransmitter input is lost in Huntington's disease?

GABA input.

What do myasthenia gravis, Parkinson's disease, and Huntington's disease demonstrate about synapses?

Small or specific synaptic problems can produce major changes in behavior and movement.

What is a psychoactive drug?

A drug that influences the brain or behavior.

What are the four main psychoactive drug classes in the lecture?

Analgesics, stimulants, depressants/sedatives, and hallucinogens.

What are analgesics?

Pain-relieving drugs.

What are endorphins?

Naturally produced, morphine-like substances in the body that can act as neurotransmitters.

What type of molecule are endorphins?

Peptides that can act as neurotransmitters.

What examples of opium-like analgesics were given?

Heroin, morphine, and codeine.

What do stimulants generally do?

Increase arousal and alertness.

What are two major examples of stimulants?

Amphetamines and cocaine.

What do cocaine and amphetamines do to dopamine reuptake according to the lecture?

They inhibit dopamine reuptake, leaving more dopamine available in the synapse.

What additional effect can amphetamines have on dopamine?

They can increase dopamine release.

What is Novocaine used for?

Local anesthesia.

How does Novocaine interfere with neural signaling?

It reduces the cell's permeability to sodium ions.

Why does reducing sodium entry stop a nerve impulse?

Sodium entry helps the neuron fire, so blocking it prevents normal conduction.

What two effects can Novocaine provide?

Anesthesia and analgesia.

What is anesthesia?

Loss of awareness or sensation.

What is analgesia?

Pain relief.

What do low doses of sedatives/depressants do according to the lecture?

Reduce anxiety and cause disinhibition.

What does anxiolytic mean?

Anxiety-reducing.

What can medium doses of sedatives/depressants do?

Cause sleep.

What can high doses of sedatives/depressants do?

Cause anesthesia, coma, or death.

What are examples of depressants/sedatives from the lecture?

Alcohol, barbiturates, and benzodiazepines.

What are examples of benzodiazepines mentioned in the lecture?

Valium and Rohypnol.

What is a hallucination?

Perceiving something even though the actual stimulus is absent.

What types of hallucinations can occur?

Auditory, visual, or tactile hallucinations.

What neurotransmitter system does mescaline act on according to the lecture?

Primarily the serotonin system.

What neurotransmitter system do "magic mushrooms" act on according to the lecture?

Serotonin receptors.

What are endocannabinoids?

Naturally occurring cannabinoid-like molecules made by the body.

How are endocannabinoids unusual compared with typical neurotransmitters?

They are synthesized on demand instead of being stored in vesicles.

Does every psychoactive drug fit perfectly into one of the four drug classes?

No. Some drugs have effects that overlap categories.

How is MDMA/ecstasy generally categorized in the lecture?

As a stimulant, although it can also cause hallucinations.

How is marijuana categorized in the lecture?

Usually as a depressant, but it can also be considered a hallucinogen.

How do analgesics/narcotics generally act at opioid receptors?

As agonists.

What opioid agonists were listed in the lecture?

Morphine, heroin, Vicodin, Percocet, fentanyl, and opium.

What three neurotransmitter systems do amphetamines affect in the lecture?

Serotonin (5-HT), dopamine (DA), and norepinephrine (NE).

How do amphetamines affect these neurotransmitter systems?

They increase release and inhibit reuptake.

What does 5-HT stand for?

Serotonin.

What does NE stand for?

Norepinephrine.

What additional action can cocaine have besides affecting neurotransmitter reuptake?

It can block voltage-gated sodium channels.

Which neurotransmitter system does MDMA/ecstasy especially affect?

Serotonin.

What major inhibitory neurotransmitter system do sedatives/depressants generally act on?

GABA.

How do many sedatives/depressants act at GABA receptors?

As agonists, increasing inhibitory effects.

Where do benzodiazepines act according to the lecture?

At their own binding site on the GABA-A receptor.

Where do barbiturates act according to the lecture?

At a different site on the GABA-A receptor.