Neuroscience Quiz: Interneurons and Conditioning

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Questions and Answers

What is the primary role of an interneuron in the central nervous system?

To initiate muscle contraction

To produce dopamine

To generate sensory information

To connect sensory and motor neurons (correct)

Which type of neuron is activated for the quadriceps during the patellar reflex?

Sensory neuron

Motor neuron (correct)

Inhibitory neuron

Interneuron

What does a Golgi stain reveal in neural imaging?

Metabolic activity

Blood flow in the brain

Cell bodies only

Dendrites and axons (correct)

Which brain imaging technique traces metabolic activity using a radioactive injection?

PET Signup and view all the answers

What is the function of commissural fibers in the cerebral cortex?

Balance excitation and inhibition between hemispheres Signup and view all the answers

Which type of secondary messenger is created from ATP by adenylyl cyclase?

cAMP Signup and view all the answers

Which structure in the basal ganglia is primarily involved in the production of dopamine?

Substantia Nigra Signup and view all the answers

What type of information can be gathered from tract tracing in neuroscience?

Connections between different brain areas Signup and view all the answers

What effect does S114R have on Kv2.1 inactivation?

It slows Kv2.1 inactivation Signup and view all the answers

What does increased frequency of action potentials lead to in terms of neurotransmitter release?

Increased neurotransmitter release Signup and view all the answers

What is the primary function of association fibers in the brain?

To transmit raw data with significance Signup and view all the answers

Which of the following ions is crucial for neurotransmitter release into the synaptic cleft?

Ca2+ Signup and view all the answers

What is the expected outcome if Kv2.1 activity is delayed?

Learning and alertness deficits Signup and view all the answers

Which neurotransmitter is primarily used by the globus pallidus internus for its outputs?

GABA Signup and view all the answers

What is the primary function of the cingulate gyrus within the limbic system?

Regulation of emotion and pain Signup and view all the answers

Which structure is associated with high-level thinking and dopamine synthesis?

Caudate nucleus Signup and view all the answers

In the context of postsynaptic potentials, what does temporal summation refer to?

PSPs arriving sequentially over time Signup and view all the answers

What is the main role of the septal nuclei in the limbic system?

Regulating the rhythm of the hippocampus Signup and view all the answers

Which neurotransmitters are involved in the frontostriatal circuit's functions?

Dopamine, Glutamate, and GABA Signup and view all the answers

Which nuclei project glutamatergic neurons to the globus pallidus internus?

Subthalamic nucleus Signup and view all the answers

What is required for an action potential to be triggered in terms of spatial summation?

Simultaneous arrival of PSPs from multiple locations Signup and view all the answers

What is the primary effect of halorhodopsin when stimulated by light?

It hyperpolarizes the neuron. Signup and view all the answers

Which receptor is directly involved in fast synaptic inhibition?

GABAA Signup and view all the answers

Which ionotropic glutamate receptor is associated with a voltage-dependent Na+ influx?

NMDAR Signup and view all the answers

What distinguishes GABAC receptors from GABAA receptors?

GABAC receptors are insensitive to benzodiazepines. Signup and view all the answers

Which enzyme is responsible for the breakdown of acetylcholine?

Acetylcholinesterase Signup and view all the answers

What kind of response is produced by the activation of AMPAR?

Fast excitatory postsynaptic potential Signup and view all the answers

Which of the following is a characteristic of GABAB receptors?

They work through G-protein-coupled mechanisms. Signup and view all the answers

Which neurotransmitter is primarily associated with the basal forebrain, pedunculopontine nucleus, and laterodorsal tegmental nucleus?

Acetylcholine Signup and view all the answers

What enzyme is responsible for the production of dopamine?

Tyrosine hydroxylase Signup and view all the answers

Which type of receptor does MDMA primarily act on?

5-HT2A Signup and view all the answers

Which of the following accurately describes the role of D1-like receptors?

They stimulate adenylate cyclase, increasing cAMP production. Signup and view all the answers

Where is serotonin produced?

Raphe nuclei Signup and view all the answers

What is the primary difference between norepinephrine and epinephrine?

Norepinephrine is a neurotransmitter, while epinephrine is a hormone. Signup and view all the answers

Which of the following statements about inverse agonists is correct?

They bind to the receptor and induce the opposite effect of an agonist. Signup and view all the answers

Which of the following best defines the therapeutic index?

The difference between effective dose (ED) and lethal dose (LD). Signup and view all the answers

Which enzyme is responsible for the production of norepinephrine?

Dopamine beta-hydroxylase Signup and view all the answers

Study Notes

Interneurons

Connect sensory and motor neurons within the central nervous system
In the patellar reflex, help coordinate the reflex arc
Relay signals between sensory and motor neurons
Excitation of quads leads to excitation of quads muscles
Excitation activates inhibition neurons for hamstrings
Motor information coming out of root leads to excitation of quads muscles, inhibition of hamstring muscles

Conditioning

Classical: Involves learning associations between stimuli
Operant: Involves learning associations between behaviors and consequences

Visualizing the Brain

Nissl Stain: Highlights cell bodies and rough endoplasmic reticulum
- Stains RNA
Golgi Stain: Selectively labels entire neurons
- Includes dendrites and axons
- Reveals full cellular morphology
MRI:
- Images brain structure
- Uses magnetic fields and radio waves
PET:
- Traces metabolic activity
- Uses radioactive injection
fMRI:
- Understands changes in blood flow
- Images activated brain areas
Tract Tracing:
- Traces pathways of axons
- Useful for understanding connectivity of different brain regions

GPCR Signaling

Gs: Stimulatory
Gi: Inhibitory
Gq: Modulatory
Secondary messengers (metabotropic): Open up ion channels from inside of cell
- cAMP: Created from ATP by adenylyl cyclase
- IP3 & DAG: Created from PIP3 by phospholipase C

Commissural vs Association Fibers

Commissural Fibers: Connect corresponding areas between the two hemispheres of the cerebral cortex
- Arise primarily from the corpus callosum
- Balance excitation and inhibition (same sides talking to each other)
Association Fibers: Connect different regions within the same hemisphere
- Arise from various cortical regions (different regions talking to each other)

Basal Ganglia

Substantia Nigra: Produces dopamine.
Caudate Nucleus: Planning movement and other high-level functions.
Putamen:
- Contains parallel circuits allowing for cortico-subcortical-cortical loops
- Inhibitory projections to the thalamus (GABAergic)
- Excitatory projections from the thalamus (Dopaminergic)
Globus Pallidus:
- Regulation of voluntary movement
- Internus: Outputs (GABA)
- Externus: Inputs (GABA)
Subthalamic Nucleus:
- Projects Glutamatergic neurons to the globus pallidus internus

Limbic System

Series of structures involved in emotion, learning, and memory
Cingulate Gyrus: Regulation of emotion and pain.
Hippocampus: Learning and memory.
- Fornix: Output tract for the hippocampus
Amygdala: Regulation of fear and emotional cues.
- Stria Terminalis: Efferent fibers from the amygdala
Septal Nuclei: Regulate the rhythm of the hippocampus

Frontostriatal Circuit

Function:
- Emotion, cognition, and motor control
- Executive function/decision making
- Motor regulation
- Reward/motivation
- Emotional regulation
Structures:
- Inferior Frontal Junction: Integrates stimuli and maintains information during a task.
- Caudate Nucleus: DA synthesis and cognitive processes.
- Thalamus: Sensory/relay station, integrates senses, supports PFC neurons during working memory delay periods.
Neurotransmitters Used:
- DA, Glu, GABA

Postsynaptic Potentials

Summate at the axon hillock to determine if an action potential will fire.
Temporal Summation:
- PSPs that reach the axon hillock at different times.
- Harder to reach threshold the further apart they are.
Spatial Summation:
- PSPs that reach the axon hillock at the same time.
- AP is triggered when summation reaches threshold

Optogenetics

Channelrhodopsin:
- Sensitive to blue wavelengths
- Opens Na+ channels
- Depolarizes the cell
- Leads to an excitatory response
Halorhodopsin:
- Sensitive to yellow wavelengths
- Opens Cl- channels
- Hyperpolarizes the cell
- Leads to an inhibitory response

Glutamatergic Signaling

AMPAR:
- Ionotropic glutamate receptors
- Glutamate binds to AMPAR
- Rapid influx of Na+ ions
- Fast excitatory postsynaptic potential (EPSP)
- Determine the neuron's firing based on speed and amplitude
NMDAR:
- Ionotropic
- Na+ influx is voltage-dependent
mGluR:
- Metabotropic GPCR
- Don't directly open Na+ channels
- Slow reaction

GABAergic Signaling

GABAA:
- Ionotropic receptors
- Function as ligand-gated chloride channels
- When GABA binds, it opens chloride channels
- Chloride ions enter the neuron
- Causes hyperpolarization (inhibition)
- Mediate fast synaptic inhibition
GABAB:
- Metabotropic receptors
- Work through G-protein-coupled mechanisms
- Activation of GABAB receptors leads to the opening of potassium channels and inhibition of calcium channels
- Causes hyperpolarization and reducing neurotransmitter release
- Mediate slow and prolonged inhibitory signaling
- Often involved in presynaptic inhibition
GABAC:
- Ionotropic receptors similar to GABAA
- Different subunit composition
- Less widely distributed in the CNS
- Found primarily in the retina
- Mediate inhibitory signaling in the retina
- Insensitive to benzodiazepines
- Chloride channels
Benzodiazepines and alcohol: Work on GABAA receptors.

Acetylcholine

Production:
- Basal forebrain
- Pedunculopontine nucleus
- Laterodorsal tegmental nucleus
Production Enzyme: Choline acetyltransferase.
Breakdown Enzyme: Acetylcholinesterase

Dopamine

Production: Dopaminergic neurons in the ventral tegmental area and substantia nigra.
Production Enzyme: Tyrosine hydroxylase and aromatic L-amino acid decarboxylase.
D1-like receptors: Stimulate neuronal activity; activate adenylate cyclase, which increases the production of cyclic AMP (cAMP).
D2-like receptors: Inhibit neuronal activity; inhibit adenylate cyclase, reducing cAMP levels.

Serotonin

Production: Raphe nuclei.
Production Enzyme: Tryptophan hydroxylase and aromatic L-amino acid decarboxylase.
5-HT1: Act through Gi/Go proteins, which inhibit adenylate cyclase and decrease cAMP levels in the neuron, reducing excitability.
5-HT2: Work through Gq proteins, which activate phospholipase C, increasing inositol trisphosphate (IP3) and diacylglycerol (DAG), leading to the release of intracellular calcium.
MDMA: Acts on 5-HT2A receptors and enhances serotonin activity by increasing its release.

Norepinephrine

Production: Locus coeruleus and lateral tegmental area.
Production Enzyme: Dopamine beta-hydroxylase.
Difference between norepinephrine and epinephrine:
- Norepinephrine: Neurotransmitter; released from sympathetic nerve terminals and influences target organs by stimulating adrenergic receptors; greater affinity for alpha-adrenergic receptors than beta-adrenergic receptors.
- Epinephrine: Hormone; secreted by the adrenal medulla during the "fight or flight" response; affects both alpha-adrenergic and beta-adrenergic receptors
- Different affinity: Norepinephrine has a greater affinity for alpha-adrenergic receptors, while epinephrine affects both alpha-adrenergic and beta-adrenergic receptors.

Agonist, Antagonist, and Inverse Agonist

Agonist: Activates a receptor to produce a biological response.
Antagonist: Blocks the receptor to prevent activation.
Inverse Agonist: Binds to the same receptor but induces the opposite effect of an agonist.

Dose Response Curves

Effective Dose (ED): The dose at which a drug produces a desired effect.
Lethal Dose (LD): The dose at which a drug is lethal.
Therapeutic Index: Represents the safety margin of a drug, the difference between ED and LD. A wider gap indicates a safer drug.

Class Review

Kv2.1:
- Delayed rectifier Kv channel
- Regulates the duration and resting membrane potential of action potential in certain cells
- Slower inactivation leads to learning deficits, alert deficits, alterations in sleep/wake cycle.

Rawat

Kiss and Run, Partial Release, and Full Release:
- Kiss and Run: 1 action potential
- More Action Potentials: More calcium and more NT release.
Neurotransmitter Release: Amount of time for fusion (Ca2+ binds to synaptotagmin) is important for releasing NT into the synaptic cleft.
Association Fibers: Connect different regions within the same hemisphere
- Integrate raw data and associate it with significance
- Multiple function to multiple regions of the brain to form complex information
Commissural Fibers: Connect corresponding areas between the two hemispheres of the cerebral cortex
- Regions of the brain have to connect with one another or be associated with one another.

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Description

This quiz covers the roles of interneurons in the reflex arc and details classical and operant conditioning. Additionally, it explores various methods for visualizing the brain, including stains and imaging technologies. Test your knowledge on these essential neuroscience topics!