Neuroscience Final

What are the two main types of synapses?

Electrical synapses and chemical synapses.

What is the primary function of synaptic transmission?

The process of information transfer at a synapse.

What is a characteristic of electrical synapses?

They allow very fast transmission and can be unidirectional or bidirectional.

What is the neuromuscular junction (NMJ)?

The synapse where motor neurons connect to muscle fibers.

What is the role of acetylcholine at the NMJ?

It binds to receptors at the end plate to initiate muscle contraction.

What autoimmune disease affects the neuromuscular junction?

Myasthenia Gravis.

What happens in Myasthenia Gravis?

Antibodies block acetylcholine receptors at the end plate, causing muscle weakness.

What are the types of synaptic arrangements?

Axodendritic, axosomatic, axoaxonal, axosecretory, dendrodendritic, and axonoextracellular.

What distinguishes excitatory synapses from inhibitory synapses?

Excitatory synapses (Gray's Type 1) have asymmetrical membrane differentiations, while inhibitory synapses (Gray's Type 2) have symmetrical differentiations.

What neurotransmitter is primarily excitatory in the CNS?

Glutamate.

What neurotransmitter is primarily inhibitory in the CNS?

Gamma-aminobutyric acid (GABA).

What is exocytosis in the context of neurotransmitter release?

The process by which vesicles release their contents into the synaptic cleft.

What is the effect of Botox on neurotransmitter release?

It degrades a SNARE protein, preventing the release of acetylcholine at the terminal.

What are transmitter gases, and give an example?

Transmitter gases like nitric oxide (NO) are produced over cells and can diffuse beyond the synapse.

What is the role of voltage-gated calcium channels in neurotransmitter release?

They allow calcium to rush inside the cell, triggering vesicle engagement and neurotransmitter release.

What is synaptic integration?

The process where multiple synaptic potentials combine within one postsynaptic neuron.

What is the axon hillock's significance?

It contains many voltage-gated channels and is crucial for action potential initiation.

What are excitable dendrites?

Dendrites that have voltage-gated sodium, calcium, and potassium channels and can amplify signals.

What is the length constant in synaptic transmission?

The distance at which 37% of the change in membrane potential remains.

How does norepinephrine modulation affect neuronal conductance?

It decreases K+ conductance and increases membrane resistance, enhancing the effect of other neurotransmitters.

What types of neurotransmitters are synthesized on ribosomes?

Peptide neurotransmitters.

What is the difference between ionotropic and metabotropic receptors?

Ionotropic receptors are fast and less selective, while metabotropic receptors are slower with a broader range of outcomes.

What is an EPSP?

Excitatory postsynaptic potential, a brief graded potential that increases the chance a neuron will fire.

What is an IPSP?

Inhibitory postsynaptic potential, a brief graded potential that decreases the chance a neuron will fire.

What are the three main classes of neurotransmitters?

Amino acids, amines, and peptides.

What is the rate-limiting step in neurotransmitter synthesis?

The specific step that limits the rate of synthesis, which varies by neurotransmitter.

What are the three criteria for a molecule to be considered a neurotransmitter?

1. Synthesized and stored in the presynaptic neuron. 2. Released upon stimulation. 3. Evokes the same response as stimulation of the presynaptic neuron.

What techniques are used to localize neurotransmitter systems?

Immunocytochemistry and in situ hybridization.

What does microiontophoresis help to study?

It mimics synaptic transmission to understand neurotransmitter function.

What is the role of an agonist in neuropharmacology?

An agonist acts like the neurotransmitter.

What is the role of an antagonist in neuropharmacology?

An antagonist works against the neurotransmitter.

What neurotransmitter is associated with excitatory synapses?

Glutamate.

What is Dale's Principle?

Each neuron has its own specific neurotransmitter, typically using one primary transmitter.

What neurotransmitter is released at the neuromuscular junction?

Acetylcholine (ACh).

What happens to cholinergic systems in conditions like Alzheimer's?

ACh dysfunction leads to cell death and memory loss.

What is the main function of the dopamine system?

It is involved in reward and motivation.

What neurotransmitter is associated with the fight or flight response?

Norepinephrine (NE) and epinephrine (adrenaline).

What is the significance of tryptophan in serotonin synthesis?

Tryptophan is the precursor for serotonin and its availability is the rate-limiting step.

What are the amino acid neurotransmitters?

Glutamate, glycine, and gamma-aminobutyric acid (GABA).

What is the function of GABA?

GABA is an inhibitory neurotransmitter.

What are transmitter-gated channels?

Channels that open in response to the binding of a neurotransmitter.

What is the role of NMDA receptors?

NMDA receptors allow Na+ and Ca2+ to enter the cell and are involved in memory processes.

What is the basic structure of G-Protein-Coupled Receptors (GPCRs)?

Single polypeptide with seven membrane-spanning alpha-helices.

What is the outcome of cAMP activation in neurons?

It activates protein kinase A, which can lead to various cellular responses.

What is the process of phosphorylation?

The transfer of a phosphate group to a protein, often altering its function.

What is the significance of sodium-dependent transporters in catecholaminergic systems?

They are responsible for the reuptake of catecholamines like dopamine and norepinephrine.

What is the role of acetylcholine esterase?

It enzymatically destroys acetylcholine to terminate its action in the synaptic cleft.

What is the effect of drugs of abuse on neurotransmitter systems?

They often block the reuptake of neurotransmitters, enhancing their effects.

What are the two big categories of synapse?

The two big categories of synapse are electrical synapses and chemical synapses. Electrical synapses allow direct ionic current flow between neurons, while chemical synapses involve neurotransmitter release and receptor binding.

What type of synapse works fastest?

Electrical synapses work fastest because they allow direct transmission of electrical signals between neurons without the delay of neurotransmitter release.

Compare and contrast G-protein coupled receptors to ligand-gated ion channels.

G-protein coupled receptors (GPCRs) are slower and involve a signaling cascade mediated by G-proteins, while ligand-gated ion channels open rapidly in response to neurotransmitter binding, allowing ions to flow directly across the membrane.

What are common synaptic arrangements?

Common synaptic arrangements include axodendritic (axon to dendrite), axosomatic (axon to cell body), and axoaxonic (axon to axon) connections.

How might you tell if a synapse is excitatory or inhibitory?

You can determine if a synapse is excitatory or inhibitory by measuring the postsynaptic potential. Excitatory synapses typically release neurotransmitters like glutamate and open sodium channels, leading to depolarization (EPSP), while inhibitory synapses release neurotransmitters like GABA and open chloride channels, leading to hyperpolarization (IPSP).

What is the neural code?

The neural code refers to the way in which information is represented in the nervous system through patterns of neuronal firing and the timing of action potentials.

How can a neuron process incoming signals?

A neuron can process incoming signals by integrating multiple inputs through summation (temporal and spatial) to determine whether to fire an action potential.

What's the difference between an IPSP and an EPSP?

An IPSP (inhibitory postsynaptic potential) causes hyperpolarization of the postsynaptic membrane, making it less likely to fire an action potential, while an EPSP (excitatory postsynaptic potential) causes depolarization, making it more likely to fire.

What are agonists and antagonists?

Agonists are substances that activate receptors and mimic the action of neurotransmitters, while antagonists block receptors and inhibit the action of neurotransmitters. Examples include morphine (agonist) and naloxone (antagonist).

What are the neurotransmitter types?

Neurotransmitter types include amino acids (e.g., glutamate, GABA), monoamines (e.g., dopamine, serotonin), neuropeptides (e.g., substance P), and gases (e.g., nitric oxide).

What makes the neuromuscular junction such a special synapse?

The neuromuscular junction is special because it is a highly specialized chemical synapse that transmits signals from motor neurons to muscle fibers, leading to muscle contraction.

What is the role of myelin in the nervous system?

Myelin insulates axons, increasing the speed of electrical signal transmission through saltatory conduction and improving the efficiency of neuronal communication.

How are neurotransmitters defined/identified?

Neurotransmitters are defined by their ability to be synthesized and released by neurons, bind to specific receptors, and produce a physiological effect on the target cell.

How might one localize neurotransmitter systems in the brain?

Neurotransmitter systems can be localized in the brain using techniques such as immunohistochemistry, in situ hybridization, and PET scans to visualize specific neurotransmitter receptors or markers.

What are the precursors for the main neurotransmitters we discussed?

Precursors include glutamine for glutamate, tyrosine for dopamine and norepinephrine, and tryptophan for serotonin.

What is the rate-limiting step for each neurotransmitter's synthesis?

The rate-limiting step varies by neurotransmitter; for example, the conversion of tyrosine to L-DOPA is the rate-limiting step for dopamine synthesis.

What kinds of receptors might each neurotransmitter have?

Different neurotransmitters have various receptors; for example, glutamate has NMDA and AMPA receptors, while dopamine has D1 and D2 receptors.

What neurotransmitter system is typically affected by Parkinson's disease?

The dopaminergic system is typically affected by Parkinson's disease, and an early treatment involves using L-DOPA to increase dopamine levels in the brain.

How are neurotransmitters cleared from the synapse?

Neurotransmitters are cleared from the synapse through reuptake into presynaptic neurons, enzymatic degradation, or diffusion away from the synaptic cleft.

What is the structure of a ligand-gated ion channel?

A ligand-gated ion channel consists of multiple subunits that form a pore; binding of a ligand induces conformational changes that open the channel, allowing specific ions to pass through.

What do various receptors do in response to ligands binding?

When ligands bind to receptors, they can induce conformational changes that either open ion channels or activate intracellular signaling pathways, leading to changes in cell function.

What are methods used to identify whether neurotransmitters are involved at synapses?

Methods include pharmacological manipulation (using agonists and antagonists), electrophysiological recordings, and imaging techniques to observe neurotransmitter release and receptor activation.

Nervous system layout (CNS vs PNS)

The central nervous system (CNS) consists of the brain and spinal cord and integrates information, while the peripheral nervous system (PNS) includes nerves outside the CNS that carry sensory input to the CNS and motor output away from it.

Gray matter

Contains neuronal cell bodies, dendrites, synapses, and unmyelinated axons; responsible for information processing.

White matter

Consists primarily of myelinated axons; responsible for communication between different brain regions.

Animal research in neuroscience

Allows investigation of basic neural mechanisms and brain-behavior relationships conserved across species that cannot be ethically studied in humans.

Regulation of animal research

Overseen by IACUC and AAALAC to ensure experiments are justified, alternatives considered, and animal pain and distress minimized.

Aristotle

Believed the heart was the seat of sensation and thought and that the brain cooled the blood.

Galen

Argued the brain controlled sensation and movement and emphasized the importance of ventricles.

Descartes

Proposed a mechanistic body and suggested the pineal gland linked mind and body.

Gall (phrenology)

Proposed that mental functions are localized to specific brain regions reflected in skull shape; incorrect method but influenced localization theory.

Flourens

Used experimental ablation and argued many brain functions are distributed rather than strictly localized.

Bell-Magendie law

Demonstrated that dorsal spinal roots are sensory and ventral spinal roots are motor.

Broca

Identified a left frontal lobe region critical for speech production.

Wernicke

Identified a temporal lobe region critical for language comprehension.

Aphasia

A language disorder caused by brain damage, often due to stroke.

Broca's aphasia

Nonfluent, effortful speech with relatively intact comprehension caused by damage to Broca's area.

Wernicke's aphasia

Fluent but nonsensical speech with impaired comprehension caused by damage to Wernicke's area.

Agnosia

Inability to recognize objects, people, or sounds despite intact sensory systems.

Neuron

A specialized cell that receives, processes, and transmits information using electrical and chemical signals.

Dendrites

Branched extensions of neurons that receive incoming signals.

Soma (cell body)

Metabolic center of the neuron containing the nucleus and organelles.

Axon

Long projection that conducts electrical signals away from the soma.

Axon terminal

End of the axon that releases neurotransmitters.

Neuron classification

Neurons are classified by structure, function, neurotransmitter, and axon length.

Glial cells

Non-neuronal cells that support, insulate, nourish, and protect neurons.

Astrocytes

Regulate extracellular ions, support neurons, and contribute to the blood-brain barrier.

Oligodendrocytes

CNS glial cells that myelinate multiple axons.

Schwann cells

PNS glial cells that myelinate individual axon segments and aid regeneration.

Microglia

Immune cells of the CNS that remove debris and dead cells.

Ependymal cells

Line ventricles and help produce and circulate cerebrospinal fluid.

Cytoskeleton

Network of microtubules, neurofilaments, and actin filaments providing structure and transport.