BCMB 415 - Foundations of Neurobiology (Part 1)

Nervous System

Central nervous system (CNS) and Peripheral nervous system (PNS)

Central nervous system

Brain and spinal cord

Peripheral nervous system

Nerves connecting CNS to the body and organs

Cerebral cortex is…

Functionally specialized

Brain uses…

Topographic maps

Brain cells =

Neurons and glia

Neurons are…

Individual cells (not fused)

Neurons communicate at…

Synapses

Two synapse types:

Chemical and electrical

What structures make up the CNS and PNS?

The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of nerves that connect the brain stem and spinal cord to the rest of the body and internal organs.

What are the major regions of the cerebral cortex and their functions?

The cerebral cortex is divided into four lobes: the frontal lobe (decision making, personality, movement), peripheral lobe (sensory processing), temporal lobe (memory and speech), and occipital lobe (vision).

What are cortical topographic maps?

Cortical topographic maps represent the organization of sensory and motor information in the brain, where specific regions of cortex corresponds to specific body parts.

What cell types are found in the brain and what do they do?

The brain contains neurons and glial cells. Neurons transmit information, while glial cells support neurons through immune defenses, metabolic support, and myelination.

Compare the reticular theory and neuron doctrine.

The reticular theory proposed that the nervous system is a continuous network of fused cells, while the neuron doctrine states that neurons are individual, separate cells that communicate at context sites called synapses.

What evidence supports the neuron doctrine?

Golgi staining, electron microscopy, and Brainbow imaging showed that neurons are individual cells with distinct boundaries and communicate through synapses rather than being fused together.

What are the two types of synapses and how do they differ?

Chemical synapses use neurotransmitters released into a synaptic cleft, while electrical synapses use gap junctions that allow direct ion flow between cells.

Which structure is part of the PNS?

A. Cerebellum

B. Spinal Cord

C. Peripheral nerve

D. Cerebral cortex

Peripheral nerve

Which lobe is primarily responsible for vision?

A. Temporal

B. Parietal

C. Occipital

D. Frontal

Occipital

The homunculus map demonstrates that:

A. All body parts have equal cortical representation

B. Larger body parts have more neurons

C. Receptor density affects cortical representation

D. The cortex is randomly organized

Receptors density affects cortical representation

Which cell type forms myelin in the CNS?

A. Astrocyte

B. Microglia

C. Oligodendrocyte

D. Schwann cell

Oligodendrocyte

Which finding disproved the reticular theory?

A. Brain lesions

B. Golgi staining

C. Behavioral studies

D. EEG recordings

Golgi staining

Neurons from a continuous network.

T/F

False

Electrical synapse contain synaptic clefts.

T/F

False

Astrocytes regulate synapse formation.

T/F

True

The PNS includes the brain.

T/F

False

Chemical synapses use neurotransmitters.

T/F

True

The CNS consists of the and __.

brain and spinal cord

is involved in language production.

Broca's area

is involved in language comprehension.

Wernicke's area

Neurons communicate at contact sites called .

synapses

Neurons vary in…

Shape and function

Neurons work in…

Neural circuits

Information is carried by…

Changes in membrane protential

Dendrites receive…

Graded potentials

Axons send…

Action potentials

Neurons can be…

Excitatory, inhibitory, or modulatory

Neurotransmitters type…

Determines subtype

Synapse location =

Strength of control

How are the shapes (morphologies) of neurons different?

Neurons differ in shape and structure depending on their function. Examples include pyramidal neurons, basket cells, motor neurons, and sensory neurons. Vertebrate neurons are usually multipolar, while invertebrate neurons are usually unipolar.

What are neural circuits?

Neural circuits are ensembles of interconnected neurons that act together to perform functions. Individual neurons contribute specialized roles within the circuit, such as sensing, integrating, or producing a response.

How is information represented within a single neuron?

Information within a neuron is represented as changes in membrane potential, which functions as electrical signals.

What type of electrical response occurs in dendrites versus axons?

Dendrites and the soma exhibit graded potentials, while axons generate action potentials that propagate without decay.

What neuronal subtypes are found in neural circuits?

Neural circuits contain excitatory, inhibitory, and modulatory neurons.

What is the effect of activating each neuronal subtype?

Activation of excitatory neurons increases the likelihood of postsynaptic firing, inhibitory neurons decrease firing probability, and modulatory neurons alter the responsiveness of the target neuron.

How does synapse location affect neuronal activity?

Synapse location affects how strongly a neuron influences its target, with synapses closer to the axon initial segment exerting greater control over action potentials generation.

Which neuron type is typically excitatory in the cortex?

A. Basket cell

B. Pyramidal neuron

C. Chandelier cell

D. Sensory neuron

Pyramidal neuron

Which electrical signal decays over distance?

A. Action potential

B. Graded potential

C. Spike

D. Threshold

Graded potential

Which neuron subtype decreases postsynaptic firing?

A. Excitatory

B. Modulatory

C. Inhibitory

D. Sensory

Inhibitory

Which synapse location has the strongest control over firing?

A. Distal dendrites

B. Soma

C. Axon initial segment

D. Axon terminal

Axon initial segment

Action potential vary in amplitude.

T/F

False

Graded potential occur in dendrites.

T/F

True

Neural circuits consist of single neurons.

T/F

False

Basket cells synapse on dendrites.

T/F

False

Neurotransmitter type determines neuronal subtypes.

T/F

True

Neurons communicate using changes in .

membrane potential

Electrical signals in dendrites are called ___ _____.

graded protentials

Electrical signals in axons are called ___.

action potentials

________ _________ decreases the likelihood of firing.

Inhibitory neurons

Chandelier cells synapse at the _ ___ ____.

axon initial segment

Based on the neuron subtype, what is the neurotransmitter associated, the synapse location, and effect.

Excitatory (Pyramidal)

Glutamate, dendritic spines, increases firing

Based on the neuron subtype, what is the neurotransmitter associated, the synapse location, and effect.

Basket cell

GABA, soma, controls integration

Based on the neuron subtype, what is the neurotransmitter associated, the synapse location, and effect.

Martinotti cell

GABA, dendrites, shapes responses

Based on the neuron subtype, what is the neurotransmitter associated, the synapse location, and effect.

Chandelier cell

GABA, axon initial segment, controls AP initiation

Based on the neuron subtype, what is the neurotransmitter associated, the synapse location, and effect.

Modulatory

DA/5-HT/NE, variable, alters responsiveness

Neurons regulate gene expression at…..

Many levels

mRNAs can be…

Transported and locally translated

Fast vs. slow atonal transport move…

Different protein types

The main transport tracks are…

Microtubules

Motor proteins…

move cargo directionally

…maintains structure at synapses

Actin

Neuronal membranes contains…

Channels, transporter, and receptors

Transporters can move molecules…

Passively or actively

Gene expression can be regulated at multiple steps before a protein is produced. How do neurons regulate gene expression?

Neurons regulate gene expression by controlling transcription of DNA into mRNA, regulating mRNA transport to dendrites or axons, localizing mRNAs for local protein synthesis, and regulating vesicular trafficking of newly made proteins.

What techniques can be used to identify the location of mRNAs within cells?

The techniques used is in the situation hybridization. It uses labeled complementary nucleic acid probes to visualize specific mRNs within cells or tissue sections.

What types of proteins are transported to the axon terminal faster than others? Why must they be transported efficiently?

Transmembrane proteins, secreted proteins, vesicles,and organelles are transported to the axon terminal faster than others (50-400 mm/day) because axon terminals are far from the soma and synaptic transmission requires continuous supply of membrane proteins and neurotransmitter-related components components. If transportation is not done efficiently, then the delayed transports would impair synaptic signaling.

What major cytoskeletal element is involved in axonal and dendritic transport?

The major cytoskeletal element is microtubules. They occupy the center of axons and dendrites and serve as tracks for long-distance transport that are composed of tubulin.

What other proteins are important for transport? What are two types and how do they function?

The other critical proteins are motor proteins. The two types of motor proteins are kinesin and dynein. Kinesin moves in a anterograde direction and moves cargos from soma to axon terminal on the plus-end (positive) directed motor. Dynein moves in a retrograde direction and moves cargos from axon terminal to soma on the minus-end (negative) directed motor. The "cargo" these proteins walking along microtubules are vesicles, mitochondria, protein complexes, and mRNAs.

What cytoskeletal element maintains structural integrity of axon terminals and dendritic spines?

The cytoskeletal element is actin (F-actin). Actin is important for cell structure and shape, growth cone dynamics, cytoplasmic streaming, and structural stability of the axon terminals and the dendritic spines.

What types of membrane proteins are found in neuronal plasma membranes? What do they allow to pass?

There are three types of membrane proteins: ion channels (allows ions to pass through the membrane), transporters (moves molecules across the membrane), and ligand-binding transmembrane proteins (receptors). The neuronal plasma membranes allow major ions like Na+, K+, Cl-, and Ca+2 (ions essential for electrical signaling and synaptic transmission) to pass through.

What is the difference between passive and active transport via transporter proteins?

Passive transport does not require energy and moves the molecule down their concentration gradient, while active transport requires energy (using ATP or ion gradients) and moves the molecule against their concentration gradient.

Which process allows neurons to make proteins at synapses?

A. Transcription

B. Vesicular trafficking

C. Local mRNA translation

D. DNA replication

Local mRNA translation

Which protein is transported fastest down the axon?

A. Actin

B. Tubulin

C. Transmembrane proteins

D. Cytosolic enzymes

Transmembrane proteins

Which cytoskeletal element acts as the main transport track?

A. Actin

B. Microtubules

C. Intermediate filaments

D. Myosin

Microtubules

Which motor protein moves cargo toward the axon terminal?

A. Dynein

B. Myosin

C. Kinesin

D. Actin

Kinesin

In situ hybridization detects proteins.

T/F

False

Dynein mediates retrograde transport.

T/F

True

Actin is the primary long-distance transport track.

T/F

False

Ion channels allow Na+ and K+ to cross membranes.

T/F

True

Passive transport requires ATP.

T/F

False

Fast axonal transport moves proteins at __.

50-400 mm/day

Microtubules are composed of ___.

tubulin

Anterograde transport is mediated by __.

kinesin

Retrograde transport is mediated by __.

dynein

Actin maintains ___ ___ structure.

dendritic spine