NSCI100-010: Psychological and Brain Sciences

What types of cells are in the brain?

Neurons (= nerve cell)- (generally) don't divide after you are born

Glia(support)- divide throughout life

What are basic survival mechanisms?

• Control of breathing and heartrate

• Regulation of water and electrolyte balance

• Appetite/feeding

• Fear of dangerous situations

Whats the outer part of the brain?

Cortex

What's the inner core of brain controls?

hypothalamus and brainstem

What makes up the central nervous system?

Consists of brain and spinal cord

What does the Peripheral nervous system contact

Muscles, Skin, and more

Axons Bundle into _____________?

Nerves

What makes up the automatic nervous system?

Sympathetic and Parasympathetic

What makes up central nervous system?

Spinal Cord and Brain

What makes up the limbic system?

hippocampus, amygdala, nucleus accumbens

What makes up the Diencephalon

Thalamus and Hypothalamus

What does the brainstem do?

General function:

Inner directed functions

- unconscious and automatic

• Control of autonomic nervous system

• Origin of neurotransmitter systems

Spinal cord

includes gray matter (cells) and white matter (axons projecting to elsewhere)

What does the spinal cord do?

sends motor signals to muscles via ventral rootsreceives somatosensory info (e.g., touch) viadorsal roots

What does cerebrospinal fluid (CSF) do?

Cushions the brain and maintains the chemical environment of neurons

Where is cerebrospinal fluid (CSF) produced

Ventricles

What are the 3 meninges and their functions?

Dura mater- 2 layers that separate at places to form sinuses

Arachnoid- weblike, adheres to dura

Pia mater- thin, adheres to brain and surrounds blood vessel branches

What is the primary motor cortex (M1)

precentral gyrus

What is the primary somatosensory cortex (S1)

postcentral gyrus

What happens if the prefrontal cortex is damaged?

distractibility, failure to plan for the future or consider consequences, lack of impulse control, loss of emotions.

What do Oligodendrocytes do?

Wrap axons in sheath of myelin and increases the conduction velocity of action potentials

What are the exposed sections of myelin called?

nodes of Ranvier

True or false: Myelin is a phospholipid

True

How do Schwann cells differ from oligodendrocytes?

They are Peripheral, not central

and

Do not cover multiple neurons with myelin

Astrocytes:

Regulate the chemical environment of neurons by maintaining ion balance and neurotransmitter levels.

Control blood flow in the brain by interacting with blood vessels.

Provide nutrients (e.g., lactate) to neurons.

Act as immune cells by responding to infections and physical injury.

Release cytokines, which are signaling molecules that regulate inflammation and immune responses.

Microglia:

The primary immune cells of the CNS, responsible for detecting and eliminating pathogens.

Remove damaged neurons and synapses through phagocytosis.

Play a role in synaptic pruning during development.

How does the voltage of a neuron differ from the outside?

The inside has a potential voltage of -70 mV

Neurons are special because

Neurons are capable of carrying electrical signals without decrement, even over large distances.

Synapses:

Gaps between neurons, switches from electrical to chemical signals

How do neurons carry information?

in the number and pattern of action potentials

Action potentials:

cyclical changes in the voltage of the inside of the cell relative to the outside

Neurons are surrounded by a cell membrane that _________________________________

impermeable to ions

What allows ions to pass through the membrane?

Channel Proteins

What would cause a voltage-gated sodium channel to trigger an action potential?

Positive Sodium entering the cell causing the membrane to become more positive

What cause sodium to enter rather than leave the cell?

electrochemical gradient

What occurs when Voltage-gated potassium channels open?

positive potassium leaves the cell, making the membrane potential go more negative.

Why does potassium leave the cell during action potentials?

it is repelled by the positive charge inside the cell (at that moment)

What is the threshold for opening the voltage-gated sodium channels?

-50 to -55 mV-

Why have unmyelinated axons?

•you can't afford the metabolic cost

•your whole body is small

•your axons have large diameters

•you are a primitive organism

Refractory period:

delay before cell can fire another action potential

How do action potentials travel along an axon

In a wave that propagates

Saltatory conduction-

depolarization gets regenerated at nodes of Ranvier (in between myelin)

Na+/K +pump restores the original ion concentration using what as energy?

ATP

Synaptic transmission-

communication between neurons (or between a neuron and muscle fiber) is (usually) chemical, rather than electrical

What are some common neurotransmitters?

• Dopamine

• Norepinephrine

• Serotonin

• Acetylcholine

• Glutamate

• Gamma

Does a neuron's function depends on its neurotransmitter or what it's connected to?

What it's connected to

Steps of action potential

1. The membrane potential at the start of the axon reacts threshold (-50mV)

2. Sodium channels open

3. Sodium enters the cell

4. Potassium channel opens

5. Potassium leaves cell

Steps of an Action Potential (More Detailed) (Short Answer Question):

1. Resting State (-70 mV)

Neuron is at rest with a stable membrane potential.

Na⁺ and K⁺ voltage-gated channels are closed.

Sodium-potassium pump maintains the resting potential.

2. Depolarization (Threshold ~ -55 mV)

When a stimulus reaches threshold, voltage-gated Na⁺ channels open.

Na⁺ rushes into the cell, making the inside more positive.

Membrane potential rapidly rises toward +30 mV.

3. Peak & Repolarization (+30 mV to -70 mV)

Na⁺ channels close, stopping Na⁺ influx.

Voltage-gated K⁺ channels open, allowing K⁺ to exit the neuron.

The inside of the neuron becomes more negative again.

4. Hyperpolarization (Below -70 mV)

K⁺ channels remain open slightly longer, causing the membrane potential to dip below -70 mV.

This prevents immediate reactivation of the neuron (refractory period).

5. Return to Resting State (-70 mV)

Sodium-potassium pump restores ion balance by pumping Na⁺ out and K⁺ in.

The neuron is ready for the next action potential.

Steps of synaptic transmission

1. synthesis

2. transport

3. vesicle fusion

4. post-synaptic binding

5. degradation

6. reuptake

What does vesicle fusion depend on?

Entry of calcium and also on several specific proteins, including SNAP-25

Ionotropic receptors:

ligand-gated ion channels (channel is opened by neurotransmitter binding, the receptor is the channel)

Metabotropic receptors:

Coupled to G-proteins, several intermediate steps, but the end result is to open an ion channel

What are the advantages and disadvantages of Metabotropic receptors

Advantage: amplification of signal with G-protein-coupled receptors and ability to change protein synthesis

Disadvantage: slow

What causes generation of EPSPs or IPSPs

neurotransmitter binding leads to channels opening in the post-synaptic membrane

EPSP =

excitatory post-synaptic potential

IPSP =

inhibitory post-synaptic potential

Examples of Fast vs Slow:

Myelinated vs unmyelinated

Chemical vs electrical synapses

Iontropic (G coupled) vs metatropic

Pheromones vs Flashes of light

Burst firing:

A way for a cell to increase its "impact"

Where do EPSPs and IPSPs travel toward

The start of the axon, but die off over time and space

CT scans

Useful for clinical diagnosis

DTI:

Allows tracing of axons specifically

What are projections between distant brain areas relevant for

Conditions like autism

EEG -

non-invasive, useful for measuring stages of sleep

low spatial resolution, high temporal resolution

EEG-

depends on synchrony between cortical cells and layered organization of cortex

PET scanning-

measures regional changes in blood flow, which changes based on which areas of the brain are most active

low spatial resolution, low temporal resolution

Advantage of PET scanning-

can use radioactively labeled molecules to estimate receptor numbers

fMRI-

larger special resolution than PET, but still low temporal resolution

can be used to determine which brain areas are active during certain tasks

Electrophysiology

Gives extremely high temporal resolution for one (or several) neurons (high enough to look at bursting)

Primary motor cortex

If it is stimulated, a body part will move

What is the problem with electrical stimulation?

The "fibers of passage" problem

How can the "fibers of passage" be solved

Optogenetics - neurons change their firing rates only when light is applied, can be targeted to cell bodies vs axons

Transcranial magnetic stimulation (TMS) -

low spatial resolution, but non-invasive

Axons vs Dendrites

Dendrites = Input (receive signals).

Axons = Output (send signals).

Axons can be myelinated for faster conduction, while dendrites are not.

Neurons have many dendrites but typically only one axon.

Axons have volted gated channels while dendrites have light gated channels

Axons are typically longer than dendrites

Axons have neurotransmitters and dendrites don't

Dendrites have EPSP's and IPSP's and Axons have action potentials

Which of the following can be done WITHOUT the involvement of the cortex?

putting on a sweater

release of hormones to prevent dehydration

recognizing someone's face

playing the piano

drinking a glass of water

release of hormones to prevent dehydration

The dorsal roots of the spinal cord carry information related to

hearing

somatosensation

motor commands

motivation

somatosensation

Which of the following is NOT true about CSF?

Group of answer choices

It can be found in chambers known as ventricles

It helps to protect the brain by cushioning it

It normally has a specific chemical composition important for maintaining neuronal health

The same CSF continually recirculates, rather than any new CSF being produced

The same CSF continually recirculates, rather than any new CSF being produced

Which of the following is a correct match between cortical lobe & function?

frontal lobe & hearing

frontal lobe & motor control

frontal lobe & touch sensation

occipital lobe & motor control

frontal lobe & motor control

The thalamus is part of the

spinal cord

brainstem

telencephalon

basal ganglia

diencephalon

diencephalon

The cranial nerves are different from the spinal nerves in that?

only spinal nerves have motor functions

only cranial nerves have motor functions

only spinal nerves carry touch information

only the cranial nerves carry information for all five senses

only the cranial nerves carry information for all five senses

The best term to describe the part of the spinal cord that is closest to a person's back is?

anterior

dorsal

rostral

ventral

dorsal

Activation of the sympathetic nervous system causes

muscles to contract

salivation

constriction of the pupil

increased heart rate

increased heart rate

Which part of the brain is especially important for long-range planning, directing attention, and guiding decision making?

hypothalamus

meninges

prefrontal cortex

basal ganglia

prefrontal cortex

The field of phrenology was correct about the fact that

a particular brain area always performs the same function in all individuals

an individual's personality can be determined by feeling the "bumps" on their skull

different parts of the brain perform different functions

every part of the brain is similar to every other part in terms of function

different parts of the brain perform different functions

Which of the following is the most important for picking up an object?

medulla

pons

parietal lobe of cortex

hypothalamus

parietal lobe of cortex

The general function of the hypothalamus is to

Group of answer choices

relay motor commands to the cortex

process visual information

cause contractions in skeletal muscle

maintain constant conditions inside the body

maintain constant conditions inside the body

Which of the following is NOT part of the limbic system?

hippocampus

amygdala

nucleus accumbens

midbrain

midbrain

Damage to the ventral root of the spinal cord in a person would cause them to have difficulty

in a task of working memory

reading

moving their body

feeling textures using the sense of touch

moving their body

The membrane potential of a particular location along an axon

is always at +50

is always at -70 mV

changes over time

is always at -50 mV

is always at zero

changes over time

During an action potential, potassium ions leaving a neuron cause its membrane potential to

become more positive

repolarize

depolarize

disappear

increase

repolarize

During an action potential, an individual potassium ion might

move from the inside of the cell's axon to the outside

change its charge from positive to negative

travel from the cell's dendrites to its axon

travel from one end of the axon to the other

move from the inside of the cell's axon to the outside

Which of the following happens FIRST during an action potential?

potassium channels open

the membrane potential at the start of the axon reaches threshold (-50 mV)

sodium channels open

sodium enters the cell

potassium leaves the cell

the membrane potential at the start of the axon reaches threshold (-50 mV)

We are able to distinguish weak versus strong stimuli based on

the movement of special fluid inside of neurons

the rate of firing of neurons

the size of action potentials

the color of neurons

the rate of firing of neurons

Which of the following ions has a negative charge?

sodium

calcium

potassium

chloride

chloride

How can you tell if an ion is positive or negative?

If its a metal it's positive

If it's not a metal it's negative

During an action potential

the axon remains at its resting potential

individual sodium ions move from the start of the axon to its end

the myelin and Nodes of Ranvier both slide along the axon from the start to its end, but the Nodes travel more slowly

a spreading wave of depolarization goes from the start of an axon to its end

a spreading wave of depolarization goes from the start of an axon to its end

Tetrodotoxin can paralyze someone because it

blocks voltage-gated sodium channels involved in action potentials

affects the somatic but not autonomic nervous system

causes potassium channels to switch from the inactivated to closed state

inhibits the sodium/potassium pump

blocks voltage-gated sodium channels involved in action potentials

Which of the following is true regarding myelin?

it is not found at the nodes of Ranvier

it decreases the conduction velocity of neurons

it is produced by microglia

it increases the length of neurons

it is not found at the nodes of Ranvier

Which of the following functions is performed by astrocytes?

regulating blood flow in the brain

increasing the velocity of action potentials

firing action potentials

detecting bacterial infections in the brain

regulating blood flow in the brain

Neurons transmit information based on

the maximum size of the action potentials

their diameter

their rate of firing action potentials

their temperature

their rate of firing action potentials

If a molecule binds to the outside of a neuron's voltage-gated sodium channels, blocking off the pore, then the result would be

the neuron's membrane potential would become more negative, due to potassium ions leaving the cell but sodium not entering the cell

the neuron would not fire any action potentials

smaller than usual action potentials would occur in the neuron (e.g., peaking at only +10 mV)

the neuron would fire slower than normal action potentials

the neuron's refractory period would become longer than normal

the neuron would not fire any action potentials